late nineteenth to early twenty-first century behavior of ... · late nineteenth to early...

ge 56 (2007) 23ndash56wwwelseviercomlocategloplacha

Global and Planetary Chan

Late nineteenth to early twenty-first century behavior of Alaskanglaciers as indicators of changing regional climate

Bruce F Molnia

US Geological Survey 926A National Center Reston VA 20192 United States

Received 30 August 2005 accepted 21 July 2006Available online 2 October 2006

Abstract

Alaskas climate is changing and one of the most significant indications of this change has been the late 19th to early 21stcentury behavior of Alaskan glaciers Weather station temperature data document that air temperatures throughout Alaska havebeen increasing for many decades Since the mid-20th century the average change is an increase of sim 20 degC In order to determinethe magnitude and pattern of response of glaciers to this regional climate change a comprehensive analysis was made of the recentbehavior of hundreds of glaciers located in the eleven Alaskan mountain ranges and three island areas that currently supportglaciers Data analyzed included maps historical observations thousands of ground-and-aerial photographs and satellite imagesand vegetation proxy data Results were synthesized to determine changes in length and area of individual glaciers Alaskan groundphotography dates from 1883 aerial photography dates from 1926 and satellite photography and imagery dates from the early1960s Unfortunately very few Alaskan glaciers have any mass balance observations

In most areas analyzed every glacier that descends below an elevation of sim 1500 m is currently thinning andor retreatingMany glaciers have an uninterrupted history of continuous post-Little-Ice-Age retreat that spans more than 250 years Others arecharacterized by multiple late 19th to early 21st century fluctuations Today retreating andor thinning glaciers represent more than98 of the glaciers examined However in the Coast Mountains St Elias Mountains Chugach Mountains and the Aleutian Rangemore than a dozen glaciers are currently advancing and thickening Many currently advancing glaciers are or were formerlytidewater glaciers Some of these glaciers have been expanding for more than two centuries This presentation documents the post-Little-Ice-Age behavior and variability of the response of many Alaskan glaciers to changing regional climatecopy 2006 Published by Elsevier BV

Keywords Alaska glaciers climate change temperature advance retreat

1 Introduction

11 Alaskan glaciers

Glaciers cover about 75000 km2 of Alaska (Fig 1)Recent estimates range from 73800 km2 (Post andMayo 1971) to 74700 km2 (Post and Meier 1980) to

Tel +1 703 648 4120 fax +1 703 648 6953E-mail address bmolniausgsgov

0921-8181$ - see front matter copy 2006 Published by Elsevier BVdoi101016jgloplacha200607011

75110 km2 (Molnia 1982) This represents about 5 ofAlaskas land area and includes glaciers on 11 mountainranges (Coast Mountains Saint Elias MountainsChugach Mountains Kenai Mountains AleutianRange Wrangell Mountains Talkeetna MountainsAlaska Range Ahklun and Wood River MountainsKigluaik Mountains and Brooks Range) one largeisland (Kodiak Island) one island archipelago (Alexan-der Archipelago) and one island chain (AleutianIslands) Glaciers in Alaska extend from as far southeast

Fig 1 AVHRR image map showing the location of the 14 glacierized areas of Alaska Current glacier cover for each region based on data presentedin Molnia (in press) is 1) Chugach Mountainsmdash sim 21320 km2 2) Saint Elias Mountainsmdash sim 14300 km2 3) Alaska Rangemdash sim 14000 km2 4)Wrangell Mountainsmdash sim 5300 km2 5) Coast Mountainsmdash sim 7280 km2 6) Kenai Mountainsmdash sim 4810 km2 7) Brooks Rangemdash b1000 km2 8)Aleutian Rangemdashsim 2000 km2 9) Aleutian Islandsmdashsim 2000 km2 10) TalkeetnaMountainsmdashsim 1000 km2 11) AhklunndashWoodRiverMountainsmdashsim 60 km2 12) Alexander Archipelagomdash b100 km2 13) Kodiak Islandmdash b50 km2 and 14) Kigluaik Mountainsmdash b1 km2 AVHRR base figure byMichael Fleming is modified from Molnia 2000

24 BF Molnia Global and Planetary Change 56 (2007) 23ndash56

as N55deg19prime and W130deg05prime about 100 km east ofKetchikan to as far southwest as Kiska Island atN52deg05prime and E177deg35prime in the Aleutian Islands to as farnorth as N69deg20prime and W143deg45prime in the Brooks RangeThe number of glaciers is unknown having never beensystematically counted but probably exceeds 100000Most are small upland cirque glaciers Approximately2000 are valley glaciers Of these valley glaciers sim 60(b01 by number) are tidewater glaciers (Viens 1995)Hence by number N999 of Alaskas glaciers areland-based or terrestrial By area tidewater glaciersoccupy sim 27000 km2 or sim 1 3 of the glacier-coveredarea of Alaska

Alaskan glaciers range in elevation from above6000 m to below sea level Most are unnamed Fewerthan 700 glaciers have been officially named by the USBoard on Geographic Names Nearly all of these namedglaciers and about 1000 additional unnamed glaciersdescend below an elevation of sim 1500 m

During the Little Ice Age (LIA) the total glacier-covered area and the number of mountain ranges andislands with glacier cover were significantly larger than

present (Molnia in press) Since then as has been thecase in all of Earths temperate glacier-covered areasthere has been a significant decrease in glacier lengtharea and thickness However the timing magnitudeand complexity of this ldquopost-LIArdquo glacier change ineach of Alaskas 14 glacier-bearing areas have beendifferent To understand these complexities a detailedassessment of each of Alaskas glacier-bearing regionswas prepared as part of the USGS comprehensive Sa-tellite Image Atlas of the Glaciers of the World series(Molnia in press) Key findings from this Atlasassessment are synthesized and succinctly presentedhere specifically to define the late 19th to early 21stcentury behavior of Alaskan glaciers in response to adocumented changing regional climate which is char-acterized by temperature increases at all monitoringstations throughout Alaska As the details presentedhere show although there is a significant thinning oflower-elevation glaciers and retreat of glacier terminithe current behavior of Alaskas glaciers varies signi-ficantly from area to area varies significantly withelevation and is extremely dynamic

25BF Molnia Global and Planetary Change 56 (2007) 23ndash56

Although not the focus of this presentation the manystudies summarized by Molnia (in press) clearly showthat Alaskan glacier behavior was also exceptionallydynamic during the LIA and the time period between theLIA and the late 19th century

Today not all Alaskan glaciers are retreating Manyglaciers at higher elevations are thickening or show nochange Several volcanoes including Redoubt Volcanoand Mt Katmai had 20th century eruptions that meltedsummit glaciers Since then new glaciers have formed intheir craters At elevations belowsim 1500 m more than adozen large non-surging glaciers including HubbardHarvard and Meares Glaciers (all currently tidewaterglaciers) Lituya and North Crillon Glaciers (formerlytidewater glaciers) and South Crillon Glacier (a laketerminating glacier) are currently thickening andoradvancing Others such as Taku Glacier (formerly atidewater glacier) and Johns Hopkins Glacier (a tide-water glacier) are fluctuating around their recent max-imum advance margins

During the post-LIA period many Alaskan glaciersdemonstrated behaviors that were not related to climatedrivers Some retreated because of tidewater glacier dy-namics while others advanced because of surge dynam-ics Both of these behaviors are addressed below

12 Alaskan climate mdash the last millennium

The term ldquoMedieval Warmrdquo is used to characterize9th to mid-15th century temperatures that were warmerthan those of the subsequent Little Ice Age (Bradley andJones 1993 Crowley and Lowery 2000) According toMann et al (1999) Northern Hemisphere mean tempe-ratures during the 11th to 14th centuries were about02 degC higher than those during the 15th to 19th cen-turies but lower than mid-20th century temperaturesThe Arctic Climate Impact Assessment (ACIA 2004)characterizes temperature trends during the last millen-nium as a modest and irregular cooling from 1000 ADto around 1850 AD to 1900 AD followed by anabrupt 20th-century warming

According to Bradley (1990) the period from 1550AD to 1900ADmay have been the coldest period in theentire Holocene During this period there is widespreadevidence of glaciers reaching their maximum post-Pleistocene positions Similarly the lowest δ18O valuesand melt percentages for at least 1000 years are recordedin ice cores for this interval (ACIA 2004) During theLIA existing glaciers advanced on all continents and ineach of the 14 Alaska regions

For Alaska Calkin et al (2001) report that wide-spread glacier advances were initiated at sim 700 yr BP

and continued through the 19th century Specific exam-ples are studies by Wiles et al (1999) and Barclay et al(1999) who performed dendrochronological investiga-tions at a number of Kenai Mountain tidewater andformer tidewater glacier sites Their work involved bothliving trees some more than 680-year-old and a 1119-year tree-ring-width chronology derived from more thana 100 logs recovered from glaciers in the western PrinceWilliam Sound area Each of these logs had beensheared or uprooted by a past glacial advance Theirwork showed that glacier fluctuations during the LIAwere strongly synchronous on decadal time scales atmany glaciers Studies at eight locations indicated thatadvances occurred during the late 12th through 13centuries and from the middle-17th to early 18thcenturies Nine glaciers showed evidence of a late 19thcentury advance Glaciers studied include TebenkofCotterell Taylor Wolverine Langdon Kings NellieJuan Ultramarine Princeton Excelsior and EllsworthGlaciers in Prince William Sound and Billings Glacier inthe southern Chugach Mountains This pattern of LIAglacier advances in mountain ranges along the margin ofthe Gulf of Alaska is similar on decadal time scales to thatof the well-dated glacier fluctuations throughout the restof Alaska

Alaskan glaciers exhibited dynamic behavior evenprior to the LIA A study of 17 coastal and near-coastalAlaskan and British Columbian glaciers (Reyes et al2006) documents a widespread glacier advance duringthe first millennium AD Glaciers at several sites beganadvancing about 200 ADndash300 AD based onradiocarbon-dated overridden forests They report thatthe advance was centered on 400 ADndash700 AD whenglaciers along a 2000 km transect of the Pacific NorthAmerican cordillera overrode forests impounded lakesand deposited moraines

13 Recent temperature trends

A compilation of mean annual and seasonal air tem-peratures for Alaskas 19 first-order observing stationswith records spanning more than a half century (Anchor-ageAnnette BarrowBethel Bettles BigDeltaColdBayFairbanks Gulkana Homer Juneau King SalmonKodiak Kotzebue McGrath Nome St Paul TalkeetnaYakutat) was prepared by the University of AlaskaGeophysical Institutes Alaska Climate Research Center(Alaska Climate Research Center 2005) It confirms thatduring the period from 1949ndash2004 (Fig 2) the averagetemperature change was an increase of sim 19 degCInterestingly more than 75 of this warming occurredprior to 1977 On a seasonal basis most of the warming

Fig 2 Chart showing the aggregatemean annual temperature departurefor Alaska for the period from 1949 to 2004) Figure is derived fromdata provided by Martha Shulski Alaska Climate Research CenterGeophysical Institute University of Alaska Fairbanks


has occurred in winter and spring with a smaller changein summer and an even smaller change in autumn Priorto 1949 air temperature data were far less abundant andfar less reliable The post-1949 trend is non-linear and ischaracterized by large annual variability The 5-yearmoving average demonstrates cyclical behavior with theperiod from 1949 to 1975 substantially colder than theperiod from 1977 to 2004 During the 1977 to 2004period very little additional warming occurred with theexception of Barrow the northernmost of the first orderstations In 1976 a stepwise shift appears in the temperaturedata which corresponds to a phase shift of the PacificDecadal Oscillation characterized by increased southerlyflow and warm air advection into Alaska during the winterresulting in positive temperature anomalies (AlaskaClimate Research Center 2005)

For the 55-year period from 1949 to 2004 meanspring temperatures increased an average of sim 22 degCmean summer temperatures increased an average ofsim 13 degC mean autumn temperatures increased anaverage of sim 05 degC and mean winter temperaturesincreased an average ofsim 35 degC Talkeetna the weatherstation closest to the Talkeetna Mountains a mountainrange where every glacier is thinning and retreatingreported a sim 30 degC mean annual temperature increasethe highest of any of the 19 locations It also reported themaximum mean annual winter temperature increasesim 51 degC Every station reported increases in mean

annual winter spring and summer temperatures Allexcept Fairbanks which experienced no change alsoreported increased mean autumn temperatures

For the period 1977ndash2004 the average temperaturechange was an increase of sim 02 degC Mean springtemperatures increased an average of sim 02 degC meansummer temperatures increased an average ofsim 055 degCmean autumn temperatures increased an average ofsim 04 degC and mean winter temperatures increased anaverage of sim 04 degC Eight stations (Anchorage ColdBay Fairbanks Gulkana Kodiak Nome St Paul andYakutat) reported decreases in mean annual temperatureTalkeetna reported a sim 18 degC mean annual temperatureincrease the highest of any of the 19 locations It alsoreported the maximum mean annual winter temperatureincrease sim 29 degC Mean annual summer temperaturesincreased at 15 of the 19 stations (Alaska ClimateResearch Center 2005)

All of Alaskas first-order observing stations are atelevations below 400 m with 14 of the 19 located lessthan 40 m above sea level Although there is unequivocalevidence of warming temperatures at lower elevationsthroughout Alaska little data have been collected in directproximity to glaciers or at higher elevations Only twoglacier-proximal meteorology stations have publishedrecords that span a quarter century ormore These stationsare located at ldquoBenchmark Glacierrdquo sites (Fountain et al1997) Their climate glacier geometry glacier massbalance glacier motion and stream runoff are beingmonitored Meteorological data collection began in 1968(USGS 2004) The Alaska stations are located at GulkanaandWolverineGlaciers at elevations of 1480m and 990mrespectively At these stations no clear long-termtemperature trend is apparent For Gulkana Glacier theaverage mean annual temperature since 1968 has beenminus41 degC For 3 of the last 5 years of record (1999ndash2003)the mean annual temperature has been colder than the 30+year average Similarly for 3 of the first 5 years (1968ndash1972) the mean annual temperature (sensor correcteddata) was also colder For Wolverine Glacier the averagemean annual temperature since 1968 has been minus13 degCFor 3 of the last 5 years of record (1998ndash2002) the meanannual temperature has also been colder than the 30+ yearaverage Similarly for 3 of the first 5 years (1968ndash1972)the mean annual temperature (sensor corrected data) wasalso colder Clearly more glacier-proximal stations anddata are needed to better understand the relationship oftemperature and precipitation change and the observedbehavior of Alaskas glaciers

With respect to precipitation Alaska has also grownsubstantially wetter during the 20th century The sparsehistorical record since 1900 shows mixed precipitation


trends with increases of up to 30 in the south south-east and interior and smaller decreases in the northwestand over the Bering Sea Between 1968 and 1990precipitation has increased by an average of 30 forAlaska west of 141deg W longitude all of Alaska exceptthe southeastern panhandle (Grossman and Easterling1994) The growing season has lengthened by more than14 days since the 1950s (Parson et al 2000)

14 Tidewater glaciers

Tidewater glaciers occur in the Coast MountainsSaint Elias Mountains Chugach Mountains and KenaiMountains What is unique about tidewater glaciers isthat they originate in upland accumulation areas traverseterrestrial areas of varying lengths as they descend to-wards sea level and then extend into the marine environ-ment where their beds extend below sea level Not onlyare their termini subject to calving but their entirelengths are subject to the same climatic conditions thataffect all of their neighboring terrestrial glaciers Hencea tidewater glacier is a terrestrial glacier that hasexpanded beyond the limit of its terrestrial environment

All current tidewater glaciers extend into or occur atthe heads of fiords that are the product of Pleistocene andolder erosion (Molnia and Carlson 1975 Carlson et al1982) From an examination of Alaskan topographicmaps and aerial photography Viens (1995) determinedthat during the last quarter of the 20th century there were51 active tidewater glaciers and 9 former tidewaterglaciers All were located between McCarty Fiord(McCarty Glacier) of the Kenai Mountains to the westand LeConte Bay (LeConte Glacier) of the Coast Moun-tains to the east Some of these glaciers like the catastro-phically retreating Columbia Glacier produce vastquantities of icebergs Some like Muir Glacier haveretreated onto land and no longer make contact with thesea These 60 tidewater glaciers have an area ofsim 26834 km2 sim 13 of the glacier-covered area ofAlaska By number they represent significantly less than01 of Alaskas glaciers

The term tidewater glacier was introduced by Russell(1897) and defined as glaciers which enter the ocean andcalve off to form bergs A similar definitionA glacier thatterminates in the sea where it usually ends in an ice clifffrom which icebergs are discharged is presented in theGlossary of Geology (Bates and Jackson 1987 pg 687)

Tidewater glaciers are part of the glacial-marine envi-ronment (Molnia 1981) and usually are very dynamicTidewater glaciers exhibit three types of terminusbehavior advance retreat and stability Except whensurging those that are advancing move forward at

maximum rates of several tens of meters per year Withthose that are retreating retreat rates are typically higherby an order of magnitude or more Generally the advanceand retreat cycle of each tidewater glacier is asynchro-nous unique to the individual glacier For exampleHarvard Yale and Meares Glaciers are three adjacentsouth-flowing tidewater glaciers in western PrinceWilliam Sound Harvard is located to the west Mearesto the east while Yale is in themiddle Since the early 20thcentury Harvard Glacier has advanced nearly 2 km Yalehas retreated more than 6 km and Meares has advancedsim 1 km The type of terminus behavior displayed isusually a function of the calving rate However parts ofYale Glaciers terminus that have retreated from its fiordto the terrestrial environment continue to retreat althoughat a lower rate Calving is defined asThe breaking away ofamass or block of ice from a glacier (Bates and Jackson1987 pg 96) In tidewater glaciers the rate of calvingmuchmore so than climate controls the glaciers terminusbehavior and length Calving glaciers lose most of theirmass by calving rather than by surface melting

An explanation for the observed dynamics of tidewatercalving glaciers was presented by Post (1975) whosuggested that the terminus of a tidewater glacier neededto be in shallow water to minimize its rate of calving andthat the rate of calving increases in an exponential fashionwith an increase in terminus water depth He suggestedthat a stable tidewater glacier had its base grounded on thefloor of a fiord with its terminus in relatively shallowwater on a terminal moraine that the glacier had built Infront of the moraine the water depth could be hundreds ofmeters If the glacier terminus was advancing it did so bypushing themoraine down-fiord This involved erosion ofthe ice contact or up-fiord side of the moraine anddeposition on the down-fiord side of the moraine If theglacier lost contact with its moraine and retreated intodeep water its rate of calving would substantially in-crease Some tidewater glaciers such as Tyndall Glacierin Icy Bay of the St EliasMountains have retreated to thehead of their fiordswhere theymakeminimal contact withtidewater and have been stable for decades

For example Field (1975b) reported that the advanc-ing Harvard Glacier was advancing at about 22 myrwhile Molnia and Post (1995) reported that between1967 and 1993 Bering Glacier had retreated as much as107 km (an average of sim 450 myr with a maximumretreat of 26 km between 1977 and 1978 Even thoughsome tidewater glaciers may have accumulation arearatios (AARs) of greater than 093 due to calving theystill are retreating Hence while the advance of a tide-water glacier is climate dependant and is a function of apositive balance the amount of retreat of a tidewater

Fig 3 A 10 km by 15 km portion of a June 24 2000 ASTER Level 1B panchromatic mosaic (scenes AST_L1B_003_06242000213409_04272003194754 and AST_L1B_003_06242000213418_04272003194744) showing the head of College Fiord inWestern PrinceWilliam Sound Glacierspresent include Yale (Y) Harvard (H) Radcliffe (R) Baltimore (B) Smith (S) and BrynMawr (BM) Of the annotated glaciers Harvard and its tributaryRadcliffe are advancing while Baltimore Smith Yale and Bryn Mawr Glaciers are retreating The white star () marks the location from which thephotographs in Fig 4 were made


glacier before stability is reached may be climate inde-pendent Details about the behavior of a number ofindividual tidewater glaciers will be described in thegeographic region sections which follow

15 Surging glaciers

Most glaciers have nearly constant average annualflow rates Some exhibit substantial variations with majorflow irregularities In the first case any variations thatoccur are generally predictable on a seasonal basis withlonger period changes occurring as the glacier responds tochanges in mass balance In the latter situation someglaciers have dramatic annual velocity changes oftencharacterized by brief periods with velocity increases of10 to 1000 times These glaciers are said to ldquosurgerdquoSurges involve large amounts of ice displacement andoften are characterized by rapid advances of the glacierterminus The first observed surge widely reported by themedia was the 1937 surge of Black Rapids Glacier in theeastern Alaska Range where the terminus advancedmorethan 5 km in less than a year (TimeMagazine 1937) Theterms ldquogalloping glacierrdquo and ldquorunaway glacierrdquo werewidely used to report this occurrence

Post (1969) offers the following definition for a sur-ging glacier one which periodically (15ndash100+years)discharges an ice reservoir by means of a sudden brieflarge-scale ice displacement which moves 10 to 100 ormore times faster than the glaciers normal flow ratebetween surges Post continues Glacier surges are not

unique events which might result from exceptional con-ditions such as earthquakes avalanches or local in-creases in snow accumulation These movementsapparently are due to some remarkable instabilitywhich occurs at periodic intervals in certain glaciersThe comment about earthquakes and avalanches is inresponse to a theory of earthquake-induced glacier ad-vance proposed by Tarr and Martin (1910) to explainchanges that they observed in glaciers of the Yakutat BayRegion following the 1899 Yakutat Earthquake Post(1965) had previously published his observations thatthe 1964 Alaskan Earthquake had not produced snowand ice avalanches or short-lived glacier advances onglaciers in the Coast Mountains St Elias MountainsChugach Mountains Wrangell Mountains and AlaskaRange Post (1965) coined the term surge because theterm ldquoadvancerdquo is frequently technically incorrect as theaffected glaciers do not always advance beyond theirformer limits The term ldquosurgerdquo is here used to describesudden large-scale short-lived glacier movementswhether a terminal advance occurs or not Surgingglaciers typically undergo alternating phases with shortperiods of active rapid flow usually lasting from 1 to3 years (surge) followed by much longer periods of slowflow lasting from 10 to 100 years (quiescence) Thequiescent stage of a surging glacier may have seasonalvelocity variations Some glaciers called ldquopulsingglaciersrdquo (Mayo 1978) exhibit frequent weak surges

Glacier surges have been observed in many parts ofthe world but the greatest concentration of surging

Fig 4 A pair of north-looking photographs taken from near the head of Harvard Arm College Fiord Prince William Sound (see Fig 3) The pairdocuments changes that occurred during the 91 years between July 1 1909 (A) and September 3 2000 (B) The 1909 photograph by US Grantshows Harvard Glacier (H) at the head of Harvard Arm with Radcliffe Glacier (R) its largest tributary flowing into it at the right of center BaltimoreGlacier (B) a retreating hanging glacier is at the left side of the photo If any vegetation is present it is on the hill slopes above the fiord (1909 mdashUSGS Photo Library Photograph by Grant 208) The 2000 photograph documents the continuing advance of Harvard Glacier which has completelyobscured the view of Radcliffe Glacier Baltimore Glacier has continued to retreat and thin Vegetation especially Alder has become established onthe hill slopes Harvard Glacier has advanced more than 09 km since 1909 (photograph by Bruce F Molnia)


glaciers is in western North America especially in the StElias Mountains eastern Chugach Mountains easternWrangell Mountains parts of the Alaska Range and inthe Icefield Ranges adjacent to the USndashCanada border(Post 1969) Most glaciers in the regions that supportsurging glaciers do not surge Post (1969) noted only 205surging glaciers out of several thousand western NorthAmerican glaciers that he examined About 75 of thesewere in Alaska Clarke et al (1986) noted that only 64

(151 of 2356) glaciers they examined in the St EliasMountains of Canada were surge type

2 Methods

In 1978 the USGS began the preparation of an 11-chapter USGS Professional Paper (Professional Paper1386 Chapters AndashK) the Satellite Image Atlas ofGlaciers of the World edited by Richard Williams and

Fig 5 A 30 km by 55 km portion of a June 24 2000 ASTER Level 1B panchromatic scene (AST_L1B_003_06242000213418_04272003194744)showing Northwestern Prince William Sound Among the glaciers present are Harriman Glacier (H) Surprise Glacier (SU) Serpentine Glacier (SE)Cascade Glacier (CA) Barry Glacier (B) Coxe Glacier (CO) and Toboggan Glacier (T) Of the annotated glaciers all except Harriman Glacier areretreating Harriman Glacier was advancing during the 1990s but has changed little during the past decade The white star () marks the location fromwhich the photographs in Fig 6 were made The white plus (+) marks the 1899 location of the combined termini of Cascade Barry and CoxeGlaciers Since 1900 they have retreated sim 7 km most of which occurred prior to 1920


Jane Ferrigno Chapter A contains a summary of TheFate of the Earths Cryosphere at the Beginning of the21st Century Glaciers Snow Cover Floating Ice andPermafrost While chapters BndashK are regional summa-ries of glacier behavior on a continental and sub-continental basis In the Satellite Image Atlas of theGlaciers of the World series the primary data set that isused to establish a global baseline for determination ofglacier terminus positions and changes is digitalimagery data collected by Landsat Multispectral Scan-

ner (MSS) sensors on the Landsat 1 2 and 3 satellitesduring the first decade of operation of the LandsatProgram between 1972 and 1981

For the Alaska Chapter Chapter K (Molnia in press)this baseline is a set of 90 Landsat I and II color-composite images compiled by the author from theLandsat data holdings of the EROS Data Center SiouxFalls SD The data set consists of an individual color-composite Landsat image for each path-row point cen-tered in Alaska that has glaciers present

Fig 6 A pair of north-looking photographs of Toboggan Glacier both taken from about the same offshore location Harriman Fiord Prince WilliamSound The pair documents significant changes that have occurred during the 91 years between June 29 1909 and September 4 2000 The 1909photograph by Sidney Paige (A) shows that early in the 20th century Toboggan Glacier was thinning and retreating and was surrounded by a largebedrock barren zone Minimal vegetation existed on the fiord-facing hill slopes By 1909 the terminus appears to have thinned to about 50 of itsformer thickness (1909mdashUSGS Photo Library Photographmdash Page 731) The 2000 photograph (B) documents the continuing thinning and retreatof Toboggan Glacier The former tributary located on the north (left) side of the glacier has also thinned and retreated significantly Note the extensivevegetation that has developed on the beach and at the glaciers margins (photograph by Bruce F Molnia)


To produce the summary presented here the authorhas supplemented this 1972ndash1981 Landsat data set withdata and information about the extent and distribution ofAlaskas glaciers derived from 18th- to 21st-centuryreports of exploration published and unpublished 19th-to 21st-century field-based scientific investigations

information extracted from numerous journal articles19th-to 21st-century ground-based photographyobtained from archives museums and libraries aroundthe world and 20th- and 21st-century aerial and spacephotography digital satellite imagery and airborne- andspace-borne-radar imagery


The most easily and frequently measured glacier pa-rameter is the geographic position of the terminusModern maps charts and satellite and airborne imagesand photographs all can be used to determine terminuspositions So can charts from early navigators andldquotraditional knowledgerdquo from Alaska Native oral histo-ries Proxy methods such as tree coring and dendrochro-nology can yield approximate dates for end recessionaland lateral moraines Together these resources were usedto determine the location of glacier termini and todocument rates of change and current behavior ofAlaskanglaciers All of these diverse types of data have been usedby investigators to make determinations about thechanging positions of Alaskan glaciers (Molnia in press)

In addition to imagery and photography another signi-ficant resource used to develop the baseline and forassessing change in Alaskan glaciers is USGS topograph-ic maps Alaska has two primary types 1) 1250000-scale (1degtimes3deg) maps published by the USGS between1949 and 1979 (glaciers appear onsim 60 individualmaps)and 2) more detailed 163360-scale maps The 163360-scale topographic maps are the most detailed USGStopographic maps of Alaska They were prepared during

Fig 7 Part of a Landsat image mosaic of Glacier Bay National Park and Pres1999 and August 10 2000 produced by Jess Grunblatt and Jeff Bennett of theand Bennett 2004) Shown is asim 16 km bysim 26 km area of Upper Muir Inlet(B) and Carroll Glacier (C) McBride Glacier is located at the head of McBrMuir Glaciers terminus is shown at its 2000 location at the head of Muir Inlet1940 at the position of the white dotted line labeled 2 in about 1960 and atabout 1940 and about 1960 Muir Glacier retreated N8 km the length of Whwhich the photographs in Fig 9 were made while the black star () marks

the same time period as the 1250000-scale maps These2920 maps have dimensions of 15 min in latitude andfrom 20 to 36 min of longitude The area portrayed oneach sheet ranges from 536 km2 to 725 km2 dependingon the latitude Glaciers appear on more than 500 of thesemaps Based on aerial photography and field surveys thequality of these maps varies significantly In remotemountainous areas with poor geodetic control errors ofseveral hundred meters may exist

The primary purpose of this presentation is tosummarize the aerial extent distribution and late 19thto early 21st century behavior of Alaskas glaciers on aregion by region basis The summary presented here willfocus on behavior during the lsquoLandsat Baseline Decadersquoand where possible extend the informational baselineboth retrospectively and prospectively Representativeexamples will be used to characterize the behavior ofglaciers in each area

Regional areas and glacier lengths and areas presentedare compiled from numerous sourcesMost regional areasare taken from Molnia (1982) or Post and Meier (1980)Most glacier length and areameasurements are from Field(1975a) Where possible other sources are referenced

erve composed of Landsat 7 TM imagery collected between August 1National Park Service Alaska LandcoverMapping Program (Grunblatt Labeled are Muir Glacier (M) Riggs Glacier (R) Burroughs Remnantide Inlet (Mc) McBride Inlet is the result of 2 km of post-1975 retreat It was located at the position of the white dotted line labeled 1 in aboutthe position of the white dotted line labeled 3 in about 1980 Betweenite Thunder Ridge (WTR) The white star () marks the location fromthe location from which the photographs in Fig 10 were made


3 Results and analyses

31 Chugach Mountains

The Chugach Mountains are a 400-km-long by 95-km-wide mountain range The eastern part of theChugach Mountains is covered by a continuous seriesof connected glaciers and accumulation areas (Field1975b) Several studies have characterized this andadjacent regions as areas experiencing a significant 20thcentury retreat (Meier 1984 Molnia and Post 1995) Astudy by Sauber et al 2000 computed the effect of thisregional ice removal on crustal deformation in theeastern Chugach Mountains Recognizing that the rangeof annual thinning of glaciers in this region ranges from1ndash6myr they computed that uplift in ablation regions ofthese glaciers ranges from 1ndash12 mmyr with the greatestuplift being located just east of the Chugach Mountainsin the Icy Bay region an area where the Guyot Glacierhas retreated more than 50 km since 1904

During the lsquoLandsat Baseline Decadersquo the ChugachMountains had a glacier-covered area of sim 21000 km2The only advancing glaciers were located in WesternPrince William Sound (Fig 3) During the baselinedecade Meares Glacier (sim 26 km long with an area ofsim 142 km2) and Harvard Glacier (sim 40 km long with anarea of sim 525 km2) were advancing while Bryn MawrGlacier (sim 8 km long with an area of sim 26 km2)Harriman Glacier (length of sim 8 km and an area ofsim 26 km2) and Columbia Glacier (sim 54 km and an areaof sim 1100 km2) advanced during the early part of thedecade Smith Glacier (sim 10 km long with an area ofsim 20 km2) was stable for most of the baseline with theposition of its termini fluctuating from year to yearAvailable evidence suggests that all other valley andoutlet glaciers in the Chugach Mountains were thinningand retreating

Through the early 21st century Meares andHarvard Glaciers (Fig 4) were still advancing whileHarriman Glacier (Fig 5) was stable All other valleyand outlet glaciers in the Chugach Mountainswhether terrestrial or tidewater were thinning andorretreating The 20th century behavior of TobogganGlacier (Fig 6) is typical of many Chugach Mountainvalley glaciers

Columbia Glacier a tidewater calving glacier andthe largest glacier in Prince William Sound is anexcellent example of the dynamic natural variability ofChugach Mountain glaciers Currently it is in cata-strophic retreat During the later part of the lsquoLandsatBaseline Decadersquo it had a pre-retreat length ofsim 665 km and ice speeds at its terminus of between 5

and 6 md Part of its terminus was grounded on HeatherIsland and an adjacent submarine moraine that protectedit from significant loss of ice through calving and retreatBut in January 1979 the glacier retreated from HeatherIsland and lost contact with its moraine Thus began anlsquoirreversible drastic retreatrsquo (Meier et al 1980) that hassince resulted in sim15 km of retreat and thinning of asmuch as 400 m By 2001 the velocity at the terminusincreased nearly five-fold to 25 md or more than 9 kmyr (Krimmel 2001)

Columbia Glacier has been observed since the late18th century According to Tarr and Martin (1914) itshowedminimal change between 1794 and 1900 Gilbert(1904) photographed and mapped the lower 15 km of theglacier in 1899 He documented a land-based advancethat occurred in 1892 and a retreat underway in 1899Grant visited the glacier in 1905 and again with Higginsin both 1908 and 1909 (Grant and Higgins 1913) Theyconcluded that the glaciers land-based terminusretreated between 1899 and 1905 advanced between1905 and 1908 and advanced even more through June1909 Tarr and Martin (1914) observed that the glaciercontinued to advance through their 1911 visit Tarr andMartin quantified the changes that they and Gilbertobserved for the 20-year period between 1892 and 1911A) 1892ndashJuly 1899 retreat of 243 m average retreat ofsim 35 myr B) July 1899ndashJune 24 1909 advance ofsim 150 m average advance of sim 15 myr C) August 231909ndashJuly 5 1910 advance of 213 m average advanceof sim 245 myr D) July 5 1910ndashSeptember 5 1910advance of 33 m average advance ofsim 200 myr and E)September 5 1910ndashJune 21 1911 advance of b30 maverage advance ofsim 38 myr Hence during the 19-yearperiod from 1892 to 1911 Columbia Glacier advancesim 290 m an average advance ofsim 15 myr Field (1932)reported an advance from 1917ndash1922 followed by aperiod of retreat By 1931 275m of recession occurred atthe west margin of the glacier sim 60 m of recession onHeather Island and from 120ndash250 m of recession alongthe land-based eastern margin This retreat was quicklyfollowed by another advance Field (1937) revisitedColumbia Glacier in 1935 and measured 1045 m ofadvance at the west margin of the glacier 72 m ofadvance on Heather Island and 25 m of advance on theland-based eastern margin In 1947 Miller (1948)observed that a recession of sim 100 m had occurredsince the 1935 advance Field (1975b) reported that anadvance of 100 m or more was underway between 1947and 1949 Eight years later (1957) he observed theglacier was slowly retreating from the moraine formedby the late 1940s advance Field (1975b) reported thatbetween 1960 and 1971 annual observations of


Columbia Glacier were made by a variety of individualsexcept for 1962 During this period the glacierexperienced a small advance between 1957 and 1961recession or minimal change between 1961 and 1968 aslight advance of a few tens of meters on land between1968 and 1969 and an advance on Heather Island and onthe eastern land-based terminus between 1969 and 1971

Small scale fluctuations of the terminus continuedthrough 1982 During the N80 yr period since Gilberts1899 visit the tidewater portion of Columbia Glacierremained in an extended stable position Catastrophicretreat of Columbia Glacier tidewater terminus began in1982 as a result of the tidewater portion of the glaciersterminus losing contact with its end moraine Between


1982 and 2000 Columbia Glacier retreated 12 kmreduced its thickness by as much as 400 m increased itsspeed from about 5 to 30 md and increased its calvingrate from 3times106 to 18times106 m3d (Krimmel 2001)Since then sim 2 km of additional retreat has occurred

32 Saint Elias Mountains

The Saint Elias Mountains are a 550-km-long by180-km-wide mountain system straddling the AlaskanndashCanadian border and paralleling the coastline of thenorthern Gulf of Alaska About 2 3 of the Saint EliasMountains are located within Alaska The Alaskan SaintElias Mountains extend northwest from Lynn Canal tothe ChugachMountains The highest peak in the AlaskanSaint Elias Mountains is Mount Saint Elias Its 5489 m-high summit which is a United StatesndashCanada borderpeak is only located about 15 km from sea level Thisclosest point is the terminus of Tyndall Glacier a tide-water glacier now stabilized at the head of its fiordElsewhere in the Alaskan Saint Elias Mountains MountBona (5005 m) Mount Vancouver (4785 m) MountFairweather (4663 m) and Mount Hubbard (4557 m) allexceed 4500 m More than two dozen other peaks haveelevations greater than 3300 m The highest peak MtLogan (6050 m) is located entirely within Canada

Hundreds of glaciers cover more than 14200 km2 ofthe Alaskan part of the Saint Elias Mountains Includedare parts of the three largest temperate glaciers in NorthAmerica Bering Glacier (sim 200 km long with an areaN5000 km2) Malaspina Glacier (with the largestpiedmont lobe of any Alaskan glacier and an area of

Fig 8 The post-Little-Ice-Age evolution of Glacier Bay is depicted in a seriesof the US National Park Service produced the base map Each map covers anGlacier (GP) extending to its Little-Ice-Age maximum position and completeand West Arms are shown The upland accumulation area of Brady Glaciermap By 1850 (b) Grand Pacific Glacier has retreated sim 50 km Within two dretreating up East Arm By 1890 (c) in West Arm Grand Pacific Glacier hasGlacier (HM) and Geikie Glacier (G) both separated from Grand Pacific GlacGlacier (R) Lamplugh Glacier (L) and Johns Hopkins Glacier (JH) all formethe mouths of their respective inlets Carroll Glacier located at the head of Quinlet between Queen and Tarr Inlets have separated from Grand Pacific GlaciArm Muir Glacier has retreated an additional 10ndash15 km Its major tributarieBurroughs Glacier (B) are thinning but still connected to Muir Glacier By 19the north crossing the Canadian Border and exposing Tarr Inlet (T) Since thretreated sim 8 km exposing Johns Hopkins Inlet In East Arm Muir GlacierInlet By 1964 (e) with the exception of Johns Hopkins Glacier which has bexperiencing a small advance all of the glaciers in West Arm continue to rettidewater and continue to retreat on land Grand Pacific Glacier is now advancof Johns Hopkins Glacier which has been advancing for more than 50 years anof the glaciers that are shown continue to retreat About this time the advancihead of Tarr Inlet A 2006 map is not presented as no change would be seen whNational Park Service

sim 5000 km2) and Hubbard Glaciers More than 50 SaintElias Mountains glaciers have lengths greater than 8 kmLittle Jarvis Glacier with a length of 32 km is one of theglaciers surveyed during the International GeophysicalYear in 1957ndash1958 (American Geographical Society(AGS) 1960) It was resurveyed by a University ofAlaska Fairbanks team in 1995 In the 38 years betweensurveys the terminus retreated about 190 m an averageof about 5 myr During the 38 yr interval Little JarvisGlacier experienced a small loss in area (1995 area of245 km km2 vs 1958 area of 25 km2) but no change involume due to a small thickening in its upper accumu-lation area (Sapiano et al 1998)

About 250 years ago there was no Glacier Bay(Fig 7) Its basin was filled by a single large tidewaterglacier an ancestral Grand Pacific Glacier that reachedinto Icy Strait The terminus location occupied insim 1750marks the Little Ice Agemaximum extent of the glacier Interms of Posts tidewater glacier model the 1750 GrandPacific Glacier was in an advanced extended position

Soon after 1750 it began to retreat By the end of the19th-century retreat exceeded 55 km resulting in anaverage annual retreat rate of sim 033 kmyr As the icecontinued to thin and retreat individual inlets began tobecome exposed each with its own unique retreating icetongue Each inlet has its own history and timing of icemovement For instance Muir Glacier located in theeastern arm of the bay separated from the main GlacierBay ice mass in the early 1860s and has retreatedcontinuously This complex sequence of glacier retreatand fiord appearance has been documented by manyinvestigators beginning with Reid (1892 and 1896)

of six maps that span the 235 yr period from 1750 to 1985 Ron Karpiloarea of sim 75 km by sim 100 km The 1750 map (a) shows Grand Pacificly filling Glacier Bay with ice The locations of what will become Eastis also shown Brady Glacier extends beyond the southern limit of theecades Muir Glacier (M) its eastern tributary will separate and beginretreated an additional 50 km It still fills all of Tarr Inlet Hugh Millerier by sim 1870 and each has a tidewater terminus in its own inlet Reidr tributaries to Grand Pacific Glacier have separated from it and all sit ateen Inlet (Q) and Rendu Glacier located at the head of Rendu Inlet theer and retreated a significant distance up their respective fiords In Easts Adams Glacier (A) Casement Glacier (C) Plateau Glacier (P) and37 (d) in West Arm Grand Pacific Glacier has retreated off the map toe late 1920s Johns Hopkins Glacier has been advancing Previously ithas retreated to the north limit of the map exposing sim 15 km of Muireen advancing for more than 30 years and Lamplugh Glacier which isreat In East Arm Casement and Adams Glaciers have retreated froming but is still north of the mapped area By 1985 (f) with the exceptiond Lamplugh Glacier which is fluctuating near the mouth of its inlet allng Grand Pacific Glacier connects with Margerie Glacier located at theen compared to the 1985 map Base map courtesy of Ron Karpilo US


Every retreating tidewater glacier that transitioned on toland has continued to retreat Many have completelydisappeared (Fig 8)

About 1890 as Grand Pacific Glacier continued toretreat in the western arm of the bay Johns HopkinsGlacier separated from it Each glacier independentlycontinued to retreat for about the next 35 to 40 yearsThen both began to advanceWhileGrand PacificGlacierhas returned to a regime dominated by active thinning andretreat Johns Hopkins Glacier continues to advanceadvancing more than 15 km since the late 1920s

Glacier Bay contains more than 50 named glaciersand one of the most spectacular fiords in Alaska Manyof its glaciers originate at elevations in excess of 2000mAbout a dozen have lengths exceeding 15 km thelongest and largest being Grand Pacific Glacier with alength of about 60 km and an area of about 650 km2 Thisglacier originates in Alaska flows through BritishColumbia and terminates in Alaska Both Brady Glacierand Carroll Glacier (Fig 9) have areas in excess of500 km2 Glacier Bay extends for more than 100 kmfrom its mouth at Icy Strait to the termini of GrandPacific Glacier at the head of Tarr Inlet and JohnsHopkins Glacier at the head of Johns Hopkins Inlet

Annual field observations by the author during muchof the lsquoLandsat Baseline Decadersquo indicate that during theperiod from 1974 to 1982 12 tidewater glaciers(McBride Riggs Muir Grand Pacific Margerie ToyatteJohns Hopkins Gilman Hoonah Kashoto Lamplughand Reid Glaciers) were actively calving icebergs intoGlacier Bay Since then the termini of several such asMuir Toyatte Hoonah and Kashoto Glaciers haveretreated above sea level About 90 years earlier whenmapped by Reid in 1890 and 1892 (Reid 1896) GlacierBay had only ten tidewater calving termini (Muir CarrollRendu Grand Pacific Johns Hopkins Reid HughMillerCharpentier Geikie and Wood Glaciers) with many oftodays glaciers still part of the much larger late 19thcentury ice mass

After 1860 Muir Glacier separated from GrandPacific Glacier and by the early 1880s its continuingretreat began to expose Muir Inlet By the end of the 20thcentury retreat exceeded 40 km From south to northMuirs side inlets Adams Inlet (sim 1905) WachusettInlet (sim 1927) McBride Inlet (sim 1946) and Riggs Inlet(sim 1966) began to appear Field and Collins (1975)report that during the 84 yrs between 1886 and 1968 theaverage rate of retreat of the Muir Glacier was 400 myrBetween 1926 and 1982 retreat totaled 30 km and the icethickness decreased more than 650 m at the location ofthe 1982 terminus (Krimmel and Meier 1989) By themid-1990s Muir Glacier retreated above tidewater and

its length had decreased to less than 30 km Hall et al(1995) used Landsat imagery to document changes inupper Muir Inlet between 1973 and 1986 In the 13 yearsbetween images Muir Glacier retreated more than 7 km(Fig 10)

Lituya Bay a 15-km-long lsquoI-shapedrsquo fiord containsthree named glaciers North Crillon Glacier CascadeGlacier and Lituya Glacier all of which were tidewater atvarious times during the 20th century A large endmoraine at the mouth of the bay a well-preserved lateralmoraine (Solomons Railroad) on the west side of the bayand tree-covered stagnant glacier ice located on the westside of the bay are evidence that an expanded andcombined LituyandashNorth Crillon Glacier filled Lituya Bayduring the early LIA sometime prior tosim 1700AD Priorto the end of the 18th century this glacier retreated nearly20 km probably through catastrophic calving retreat andseparating into numerous tributaries In l786 whenmapped by LaPerouse the bay was lsquoT-shapedrsquo withfive glaciers present at its head a pair in each of the upperends of the lsquoTrsquo and a hanging glacier at the center of thelsquoTrsquo In the sim 10 km-long top of the lsquoTrsquo each glacierterminated at or near tidewater Lituya Glacier thewestern-most of the five descended from the FairweatherRange into Desolation Valley and flowed in bothdirections with the southeastward flowing lobe endingin Lituya Bay Between the observations of LaPerouse in1786 (LaPerouse 1799) and USGSmapping in 1917 thetidewater termini of Lituya Glacier advanced about 5 kmwhile that of North Crillon Glacier advanced about 3 kmEach has advanced sim 1 km since 1920 and eachcontinues to advance Since being mapped by the authorin 1976 (Molnia and Wheeler 1978) both have builtoutwash fan-deltas around their termini that separatedthem from tidewater and ceased to calve icebergs

Most adjacent glaciers are retreating For exampleGrand PlateauGlacier with a length of 50 km and an areaof about 455 km2 has been retreating and thinning formore than a century Its LIAmaximum position adjacentto the Gulf of Alaska coastline was at least 2 km south ofits 1906ndash1908 terminus position By 1941 at least fiveice-marginal lakes had developed the largest being morethan 2 km wide By 1966 the entire southern margin ofthe glacier was surrounded by a single ice-marginal lakeformed by the enlargement of the original individuallakes This lake which was 7 km by 5 km in 1975continued to enlarge through the early 21st century as theglacier calved icebergs thinned and retreated GrandPlateau Glacier is a good example of a lacustrine calvingglacier Through the late 20th century its terminusbehavior has closely resembled the retreat dynamics of atidewater glacier

Fig 9 A pair of northwest-looking photographs both taken from the same location several hundred meters up a steep alluvial fan located in a sidevalley on the east side of Queen Inlet Glacier Bay National Park and Preserve showing changes that have occurred to Carroll Glacier and upperQueen Inlet during the 98 years between August 1906 and June 21 2004 The 1906 photograph by CW Wright (A) shows the tidewater calvingterminus of Carroll Glacier (C) sitting at the head of Queen Inlet (Q)mdash (USGS Photo Library Photograph by Wright 333) No vegetation is visibleThe 2004 photograph (B) shows that the terminus of Carroll Glacier has become a stagnant debris-covered terminus that has thinned by N50 m andretreated from its 1906 position The head of Queen Inlet has been filled by N125 m of sediment Note the vegetation on the sediment fill and fiordwall (photograph by Bruce F Molnia)


Hubbard Glacier the largest tidewater glacier inAlaska is gt120 km long with an area of sim 3875 km2 Ithas a calving face that is more than 10 km long Plafkerand Miller (1958) report based on a radiocarbon-datedsample that 1130+minus160 yr BP the Hubbard Glacierfilled Yakutat Bay and extended into the Pacific OceanArcuate ridges at Monti Bay and near the city of Yakutatare the terminal and recessional moraines that mark this

maximum ice advance Beginning in the 14th centurythe Hubbard then underwent a significant retreat of morethan 25 km During the 18th century it readvanced morethan 10 km to Blizhni Point (Plafker andMiller 1958) Asubmarine moraine at the lower end of DisenchantmentBay resulted from this advance which culminated afterl700 AD From the late 18th century through the early19th century another period of retreat amounting to

Fig 10 A pair of northeast-looking photographs both taken from Station 4 on White Thunder Ridge Muir Inlet Glacier Bay National Park andPreserve The pair documents changes that have occurred during the 63 years between August 13 1941 and August 31 2004 The 1941 photograph(A) byWilliam O Field showsMuir Glacier (M) and Riggs Glacier (R) filling Muir Inlet and extended south beyond the right edge of the photographThe maximum ice thickness is N800 m Note the absence of any vegetation in the 1941 photograph (1941 National Snow and Ice Data Centermdash Field41ndash64) The 2004 photograph (B) documents the retreat of Muir Glacier out of the field of view and the significant thinning and retreat of RiggsGlacier Note the dense growth of alder and the correlation between Muir Glaciers 1941 thickness and the trimline (minus) on the left side of the 2004photograph (photograph by Bruce F Molnia)


more than 5 km occurred A detailed history of theHubbard Glaciers LIA behavior is presented by Barclayet al (2001)

Prior to 1890 Hubbard Glacier again began toadvance an advance that continues into the 21st centuryTrabant and Krimmel (2001) compared terminuschanges between 1895 and 1998 They found that the

average rate of advance has accelerated from about 16myr between 1895 and 1948 to about 26 myr between1948 and 1998 The 100-yr average advance rate issim 22 myr for most of the terminus In 1986 and again in2002 Hubbard Glaciers advancing terminus blockedthe entrance to Russell Fiord with push moraines In eachcase the water level in Russell Lake rose more than


15 m Following failure of the sediment and ice damscatastrophic floods resulted Each removed more than500 m of the terminus

During most of the 20th century Tyndall Glacier(Fig 11) a tidewater glacier located in Taan Fiord at thehead of Icy Bay was in retreat Originally a tributary toGuyot Glacier it became independent in 1960 By 1990 itretreated an additionalsim 17 km before reaching a positionof stability at the head of its fiord At its 2005 terminusposition the glacier issim 700m thinner than it was in 1959The current terminus location is only about 12 km from thesummit of Mt St Elias (at an elevation of 5489 m) This46 gradient is one of the steepest on Earth

33 Alaska Range

The Alaska Range consists of a number of adjacentand discrete mountain ranges that extend in an arc more

Fig 11 A 20 km by 30 km portion of a June 06 2001 ASTER Level 1B panchpart of Icy Bay To the right is essentially iceberg-free Taan Fiord (TF) with TyBay with the actively iceberg-calving Yahtse Glacier (Y) at its head Both Yahthe first decade of the 20th century Guyot Glacier has retreated sim 50 km opeterminus remained in the narrow neck of the bay between Kichyatt Point (KP)become exposed at the head of Icy Bay A part of the stagnant debris-coveredof the image

than 750 km in length From east to west named rangesinclude the Nutzotin Mentasta Amphitheater Clear-water Tokosha Kichatna Teocalli Neacola TordrilloTerra Cotta and Revelation Mountains Many rangessupport glaciers The Alaska Range contains severalthousand glaciers ranging in size from tiny unnamedcirque glaciers with areas of b1 km2 to very large valleyglaciers with lengths exceeding 75 km and areas of morethan 500 km2 Alaska Range glaciers extend in elevationfrom above 6000 m near the summit of MountMcKinley to a little more than 100 m above sea levelat Capps and Triumvirate Glaciers In all the AlaskaRange supports sim 13725 km2 of glaciers

Gulkana Glacier is one of two Benchmark Glaciers inAlaska It was visited and photographed by Moffit in1910 and again by Pewe in 1952 In the 42 years betweenphotographs Gulkanas terminus retreated more than4 km A comparison of the 1957 USGS topographic map

romatic scene (AST_L1B_003_2003276802) showing the northeasternndall Glacier (T) at its head To the center is the eastern part of upper Icytse and Tyndall Glaciers are former tributaries to Guyot Glacier Sincening Icy Bay For more than two decades (1939ndash1960) Guyot Glaciersand the north side of Taan Fiord Since 1960 four separate fiords haveterminus of the Malaspina Glacier (M) is present at the lower right edge


and data obtained during an airborne profiling surveyconducted on 12 June 1993 (Echelmeyer et al 1996)indicates that the glacier retreatedsim 175 km During the36 years between data sets the glaciers area decreased8 from 185 km2 to 170 km2 The average annualretreat rate was 486 myr

Rates of retreat and thinning at Gulkana Glacierincreased at the end of the 20th century (personal com-munication March 2001 K A Echelmeyer Universityof Alaska Fairbanks) Between the 1950s and middle1990s the glacier thinned 0434 myr and had its volumedecrease by 000822 km3yr Between the middle 1990sand 1999 the glacier thinned by 0748 myr and had itsvolume decrease by 00136 km3yr

Muldrow Glacier is typical of many Alaska Rangedebris-covered glaciers It is also a surging glacier (Post1960 1969) It flows to the northeast from high on theslopes ofMountMcKinley Two named tributary glaciersBrooks and Traleika Glaciers furnishmuch ofMuldrowsice From May of 1956 through the summer of 1957Muldrow Glacier surged a distance of sim 65 km Themaximum observed velocity during the peak of move-ment was sim 350 md or about 24 cmmin Surface levelsdropped up to 100 m in the upper glacier area andincreased 200 m in the lower glacier For almost a decadeprior to the surge a wave of thickening ice moved downthe upper part of the glacier at a rate of sim 075 md Post(1960) who described the 1956ndash1957 surge reported thatan analysis of moraine patterns on the glaciers surfacesuggests that at least four prior surges occurred withinthe past several hundred years with the most recent pre-1956 surge occurring between 1906 AD and 1912 Alarge moraine down-valley from the terminus wasformed by a late 16th or early 17th century advance andrepresents the LIA maximum position of MuldrowGlacier Ice stagnation and retreat followed but about150 years ago this was interrupted by a new surge thatdeposited a second set of moraines from sim 15 to45 km behind the 16th or 17th century moraines The1957 surge overrode much of the second set ofmoraines Vegetation covers the ablating stagnantice-cored moraine of the glaciers terminus for a distanceof two or more kilometers from the terminus Since thelast surge the glacier has thinned by tens of meters withlittle change in terminus position

At the start of the lsquoLandsat Baseline Decadersquo all ofthe non-actively surging valley glaciers in the AlaskaRange were stagnating thinning andor retreating(Denton and Field 1975) Several glaciers surged earlyduring the baseline period but no terminus advanceswere reported or subsequently documented At the end ofthe 20th century and into the early 21st century all of the

valley and outlet glaciers in the Alaska Range continuedto thin andor retreat (Fig 12) Some glaciers with debris-covered termini such as Ruth Glacier have vegetationgrowing on their near-stagnant termini

34 Wrangell Mountains

The Wrangell Mountains are a large young volcanicmassif with amaximum length of about 155 km andwidthof 85 km Mount Blackburn (4996 m) Mount Sanford(4949 m) Mount Wrangell (4317 m) Regal Mountain(4440 m) Mount Jarvis (4091 m) Mount Zanetti(3965 m) Rime Peak (3883 m) and Mount Drum(3661 m) are the highest peaks Mount Drum andMount Sanford are separate nearby volcanic constructsthat support a number of glaciers which radiate from theirsummits In total the Wrangell Mountains support about50 outlet glaciers with lengths of 8 km or more and havean ice-covered area of sim 5000 km2 Many of the glacierssurge (Post 1969)

At the center of the west-central Wrangell Mountainsis a broad upland ice fieldWrangell Icefield covering anarea ofsim 750 km2 It extends eastward from the crater ofMount Wrangell to the head of Nabesna Glacier adistance ofsim 35 km It is bounded on the north byMountSanford and Mount Jarvis

Mount Wrangell is the youngest and only currentlyactive volcano in the Wrangell Mountains Glaciologicalinvestigations have been conducted at the its summitsince 1961 (Benson 1968) The 4times6 km summit calderais topped by an ice cap with ice flowing outward in alldirections (Benson et al 1975) The summit calderasdepth approaches 1 km (Benson and Motyka 1978Clarke et al 1989) A prominent feature on the calderasrim is North Crater one of the three rim craters Themean annual temperature at the summit is sim`20 degCconsequently all melting at the summit caldera is byvolcanic heat (Benson and Follett 1986) Annual snowaccumulation at the summit is sim 130 cm of waterequivalent (Benson et al 1975) In 1966 Benson et almeasured a basal ice melt rate of 147 cmd (Bensonet al 1975) Using a conduction-only heat transportmodel they calculated that a heat flow of 900ndash1800 μcalcm2s is necessary to account for the observedmelting They state that this heat flow is sim 1000 timesgreater than Earths average geothermal heat fluxBenson and Motyka (1975) show that the geothermalheat flux had increased significantly since the 27 March1964 Alaskan Earthquake They report a melting ofN22times106 m3 of ice in the North Crater an order ofmagnitude increase in the area of exposed rock and asettling of the glacier surface of up to 160 m since 1964

Fig 12 A pair of north-looking photographs both taken from the same location near the retreating unnamed valley glacier that heads the East Forkof the Teklanika River Denali National Park and Preserve The pair documents changes that have occurred during the 85 years between June 1919and early August 2004 The 1919 photograph by Stephen Capps (A) shows the then retreating near-vertical debris-covered terminus (D) of theglacier having an elevated lateral moraine (L) on its west (left) side Small tundra plants are the only identifiable vegetation (USGS Photo LibraryPhotograph by Capps) The 2004 photograph (B) by Ron Karpilo US National Park Service documents the continued thinning and retreat of theunnamed glacier The glacier has retreated N300 m since 1919 retreating at an average rate of sim 4 myr


They also report that the average heat flux over the pastdecade had exceeded 1000 μcalcm2s

Between 1965 and 1984 Benson and Follett (1986)report that the craters ice continued to thin with itssurface elevation decreasing by nearly 200 m They statethat between 1965 and 1976 about 32times107 m3 of icewas lost to melting and evaporation In the 20 yearsbetween 1965 and 1984 sim 85 of the craters icedisappeared To account for this ice loss they state thatan average volcanic heat flux of 62 Wm2 is required

This is sim 1400 times Earths average heat flux Else-where in the summit caldera little change has been notedin the surface elevation of the ice cover

Seasonal studies (Sturm 1995) and photogrammetricinvestigations (Sturm et al 1991) show that the 30-km-long Athna Glacier and the smaller South and CenterMackeith Glaciers have been advancing from 5ndash18 myrsince the onset of increased heat flux following the 1964earthquake All of Mount Wrangells other outlet gla-ciers have remained stationary or retreated Sturm states


that the advancing glaciers display little seasonalvariation in surface velocity while other glaciers suchas East and West Chetaslina Glaciers experience a 50increase in surface velocity in spring and summer Theseglaciers have a common accumulation zone locatedaround the North Crater

NabesnaGlacier with a length of 87 kmwith an area ofsim 815 km2 is the largest of the outlet glaciers and is alsothe largest inland glacier in North America with as manyas 40 tributaries Capps (1910) first visited Nabesnasterminus in 1908 At that time the first 3 km of the glacierwere covered by thick debris He states that ldquoThe extent ofthe terminal moraine shows that the glacier is at presentretreating It has been deposited so recently that over mostof it no vegetation has as yet obtained a foothold rdquoRetreat continues

During the lsquoLandsat Baseline Decadersquo three glaciersAthna Glacier and South and Center Mackeith Glacierswere advancing apparently in response to non-climaticdrivers (Sturm 1995) All of the other valley and outletglacier in the Wrangell Mountains were retreating thin-ning or stagnating At the end of the 20th century andinto the early 21st century no additional information wasavailable about Athna Glacier and South and CenterMackeith Glaciers All other valley and outlet glaciers inthe Wrangell Mountains continued to thin andor retreat

35 Coast Mountains

The Coast Mountains form the mainland portion ofsoutheastern Alaska extending for about 690 km fromPortland Canal to the south to Skagway to the northFrom east to west the glacier-covered area of the CoastMountains is as much as 130 km wide Included in theCoast Mountains are a number of individual ranges Pea-body Mountains Rousseau Range Halleck Range Sew-ard Mountains Lincoln Mountains Buddington RangeKakuhan Range Chilkoot Range Sawtooth Range andTakshanuk Mountains all of which support glaciers Tothe south the glaciers are small and sparsely distributedThey increase in size and number to the north Thegreatest concentrations of Coast Mountain glaciers are intwo icefields the Stikine and the Juneau Icefields Whenmapped in the 1950s the Coast Mountains had a glacier-covered area of sim 7250 km2

The two best known and studied glaciers of the CoastMountains are the Mendenhall and Taku GlaciersMendenhall Glacier a terrestrial glacier with a lengthofsim 20 km and an area ofsim 100 km2 has retreated morethan 5 km from its LIA maximum position Its post-LIAbehavior is similar to more than 2 dozen other JuneauIcefield outlet glaciers Lawrence (1950) determined that

Mendenhalls retreat began between 1767 and 1769 andthat by 1910 the terminus had retreated about 1500m anaverage retreat rate of about 10 myr This period ofretreat included a readvance that tilted trees in the mid-1800s Between 1910 and 1949 the last year ofLawrences field investigation the glacier had retreatedanother 15 km at an average rate of nearly 40myr Nearthe beginning of the 20th century the continuing retreatbegan to expose a bedrock basin which became thelocation of an ice-marginal lake that fronted the centralportion of the glaciers terminus Through about 1940ongoing retreat exposed more of the basin and enlargedthe lake One reason for the significant difference in pre-1910 versus post-1910 retreat rates is the addition ofcalving as a means of ice loss Previously with a land-based terminus ignoring sublimation only melting wasresponsible for ice loss With the development of the ice-marginal lake a single calving event could remove avolume of ice from the glaciers terminus equal to whatotherwise would take weeks or months to loose bymelting Mendenhall Glacier continues to retreatCalving is the most significant cause of retreat of thelacustrine portion of the glacier while melting isresponsible for the continuing thinning and retreat ofthe land-based part of the glacier

Taku Glacier is 60-km-long with an area of about860 km2 It was advancing during the Landsat baselineperiod then stable for about a decade and then began toreadvance at the start of the 21st century The terminus ofTaku Glacier advanced 7 km between 1890 and 1990 Italso was overriding moraines and outwash of NorrisGlacier located to its southwest At the end of the 19thcentury when the recent advance of Taku began it was atidewater calving glacier with depths in its fiordexceeding 100 m When photographed by the AlaskaAerial Survey Expedition in the late 1920s the terminuswas still tidewater Sediment produced and transportedby the advancing glacier began filling upper Taku Inletso that by the mid-1930s ships that previously hadaccess to the terminus of the glacier could not enter theInlet About 1937 Taku Glaciers advancing terminusbegan forming a push moraine that protected the ter-minus and restricted calving This phase of advancecontinued until about 1988

Followingmore than a decade of stability the terminusbegan to advance Motyka et al (2001) report that bet-ween late 2000 and the summer of 2001 Taku Glacierbegan to readvance at a rate of 30 cmd The advancecaused a striking deformation of adjacent proglacial sedi-ments Compression by the advancing ice has caused theoutward propagation of at least two prominent bulges themore distal (width 35 m height 3 m) at a rate of about


10 cmd and the more proximal (width 80 m height45 m) at a rate of 15 cmd There are no visible thrustfaults in the sediments but shear must be occurring as partof bulge propagation While stationary during the 1990sthe terminal region continued to thicken with surfaceelevation rising at an average rate of 14 myr Previouswork showed that this glacier is actively excavating softsediments and entrenching itself into these sediments asits terminus continues to grow and advance When ob-served by the author between 2004 and 2006 the centralpart of Taku Glaciers terminus was continuing toadvance while its lateral margins were experiencing asmall amount of retreat (Fig 13)

Fig 13 Two June 19 2004 photographs of the terminus of Taku Glacier (A) sin contact with a vegetated bar while (B) shows Taku Glaciers eastern matrimline Photographs by Bruce F Molnia

Nolan et al (1995) used radio-echo sounding andseismic reflection techniques to measure Taku Glaciersice thickness and bed morphology The maximum icethickness they measured was about 1477 m and theminimum bed elevation was about 600 m below sealevel They determined that the sub-sea level basin thatunderlies the glacier extends about 50 km up-glacierFuture retreat of the glacier would expose a deep fiordbasin extending well into the Coast Mountains Theyalso compared the surface elevation in 1989 the date oftheir survey with the 1948 surface elevation determinedfrom photogrammetry They state that the glacier hadthickened by ldquo10ndash25 m over the past 40 yearsrdquo but

hows the advancing central part of Takus terminus where the glacier isrgin where the glacier appears to be thinning and has a conspicuous


measurement of differences of 1948 versus 1989 surfaceelevations from their Fig 4 shows thickening ofmore than100 m on the northeast side of the transect Regardless ofthe actual amount of thickening the positive massbalance so close to the glaciers terminus is significant

Herbert and Eagle Glaciers located immediately northof the Mendenhall Glacier have similar retreat histories tothat of the Mendenhall Glacier Both developed ice-marginal lakes during late 20th century retreat Aswas thecase of theMendenhall Glacier retreat rates increased dueto calving The development of an ice-marginal lakeduring retreat due to exposure of a previously deepenedpart of the glaciers bed that fills with water is not un-common in the retreat of other terrestrial Alaskan glaciers

During the first 2 3 of the 20th century (1902ndash1964)Chickamin Glacier (25 km long with an area ofsim 140 km2) retreated more than 27 km by melting an

Fig 14 A June 9 2001 ASTER Level 1B panchromatic scene (AST_southeastern Kenai Mountains including parts of the Sargent (S) and Hardin(EX) Ellsworth Glacier (EL) Godwin Glacier (G) Bear Glacier (B) and Aiarapidly retreating Aialik Glacier is retreating very slowly and currently is wittwo largest outlet glaciers of the southern Sargent Icefield Resurrection Baythe Pleistocene At that time greatly expanded glaciers covered much of the Gnear the east shore of Resurrection Bay during the 18th century (Davidson 19Age The white star () marks the location from which the photograph in Fi

average retreat rate of sim 44 myr (Field 1975d) Some-time after it was mapped (USGS 1955) and August 1979when it was photographed by the Alaska High-AltitudeAerial Photography Project (AHAP) it retreated about akilometer and formed an ice-marginal lake During thelast two decades of the 20th century it retreated N15 kmRetreat continues and it is currently forming a new ice-marginal lake Since 1902 Chickamin Glacier has re-treatedsim 52 km with an average retreat rate of N50myr

LeConte Glacier the southernmost tidewater glacier inthe Northern Hemisphere has a length of about 35 km anarea of 487 km2 and ice speeds near its terminus of up to23md (Post andMotyka 1995 Echelmeyer andMotyka1997) At the end of the 20th century LeConte Glacierhad an extremely active calving terminus producing largequantities of icebergs from a 50 m high face Between1887 when it was first charted and 1963 LeConte

L1B_003_06092001214033_06182001095021) showing part of theg (H) Icefields Among the larger glaciers present are Excelsior Glacierlik Glacier (A) Of the annotated glaciers all except Aialik Glacier arehin 200 m of its 1909 position Excelsior and Ellsworth Glaciers are the(RB) and Day Harbor (DH) are fiords that have been glacier-free sinceulf of Alaska (G OFA) continental shelf Godwin Glacier extended to04) Aialik Glacier expanded into Aialik Bay (AB) during the Little Iceg 16 was made


Glacier retreated 37 km (Post and Motyka 1995) Thiswas followed by a period of terminus stability from 1963to 1994 Between 1994 and 1998 the glacier retreated anadditional 2 km much of it by submarine calving(Echelmeyer and Motyka 1997 Hunter et al 2001)When observed by the author in 2003 it was continuing tocalve and retreat

During the lsquoLandsat Baseline Decadersquo Baird Glacier(50-km-long with an area of about 785 km2) Taku

Fig 15 A pair of northeast-looking photographs taken from about 8 km northdocuments changes that have occurred during the 95 years between July 30shows the east side of the terminus of the then retreating McCarty Glacier a tbut beach grass is present in the foreground and trees are present on the back b2004 photograph (B) shows part of the retreated McCarty Glacier more than 1vegetation featuring alder willow and spruce have become established on

Glacier (60-km-long with an area of about 700 km2)Hole-in-the-Wall Glacier (a distributary lobe of TakuGlacier) and Mead Glacier (37-km-long with an area ofabout 400 km2) were advancing Available evidencesuggests that all other valley and outlet glaciers in theCoast Mountains were thinning and retreating At theend of the 20th century Taku Glacier was advancing andHole-in-the-Wall Glacier was stable Since 1979 MeadGlacier retreated sim 2 km and formed an ice-marginal

of the mouth of McCarty Fjord Kenai Fjords National Park The pair 1909 and August 11 2004 The 1909 photograph (A) by US Grantidewater glacier Little if any vegetation is present on the upper slopeseach to the right (USGS Photo Library Photograph by Grant 143) The6 km up bay Much of the retreat occurred prior to 1970 Dense diversethe hill slopes and back beach areas (photograph by Bruce F Molnia)


lake All other valley and outlet glaciers in the CoastMountains were thinning and retreating When observedbetween 2004 and 2006 Taku Glacier showed evidenceof continuing retreat in its central terminus region

36 Kenai Mountains

The Kenai Mountains (Fig 14) with maximum ele-vations approaching 2000 m are a 195-km-long by 35-


km-wide mountain range Most of the Kenai Mountainglaciers descend from two large icefields the Sargentand the Harding Icefields and two smaller icefields theBlackstone-Spencer and the Grewingk-Yalik IcefieldsA number of other generally smaller glaciers descendfrom other isolated accumulation areas along the crestsof many ridges and mountains Combined the Sargentand the Harding Icefields cover more than 4000 km2 andhave glaciers that descend into Prince William SoundCook Inlet and Gulf of Alaska drainages Many glaciersreach to near sea level and more than a dozen havecalving termini eleven directly into tidewater This re-gion contains several hundred glaciers with nearly all ofthe larger glaciers having names Seven have lengths ofabout 20 km while two exceed 30 km

During the lsquoLandsat Baseline Decadersquo the KenaiMountains had a glacier-covered area of sim 4750 km2With the exception of Aialik Glacier (sim 18 km long withan area of sim 120 km2) and McCarty Glacier (sim 13 kmlong with an area of sim 110 km2) all of the valley andtidewater glaciers in the Kenai Mountains werestagnating thinning andor retreating Aialik andMcCarty Glaciers each advanced more than 500 mduring the second half of the 20th century Howeverwhen observed between 2004 and 2006 both wereretreating By the end of the 20th century all of thevalley and outlet glaciers in the Kenai Mountains werethinning stagnating andor retreating When observedin 2000 Tiger Glacier was at about the same location asit was in 1908 Having been in retreat since about 1960(Field 1975c) Tiger Glacier must have experienced alate 20th century advance to regain its former positionMcCarty Glacier (Fig 15) a tidewater glacier located atthe head of McCarty Fiord was first mapped in 1909 byGrant and Higgins (1913) It retreated about 32 kmbetween 1909 and 1927 retreated another 19 kmbetween 1927 and 1950 and another 14 km through1978 Between 1978 and the middle 1990s the terminusadvanced sim 700 m Adalgeirsdottir et al (1998) reportthat between the 1950s and middle 1990s McCartyGlacier ice volume increased by 15 km3 and its averageelevation increased by 62 m Since the mid-1990s it hasretreated N250 m

Anchor and Ogive Glaciers are two very small re-constituted glaciers inNorthwestern Fiord Each a former

Fig 16 A pair of images showing recent changes in the terminus of Bear Glaciepanchromatic scene (AST_L1B_003_06092001214033_06182001095021) shoThe line of stars () marks the glaciers early 20th century terminus position Dlarge tabular pieces of ice from its terminus and lateral margin a process knownline drawn between the two white plus signs (+) marks the approximate locatiooblique aerial photograph by Bruce F Molnia of the lower part of Bear GlacierMuch of the retreat was through the loss of large tabular pieces of ice such as

tributary to Northwestern Glacier reaches tidewater Bothadvanced a few meters between 2004 and 2005 Bear(Fig 16) Ellsworth and Excelsior Glacier are three largelake terminating valley glaciers that are located adjacentto Resurrection Bay Early in the 20th century each had aterrestrial terminus Subsequent retreat exposed deeplyeroded segments of their beds which became ice-marginallakes at each glacier Rapid retreat has followed

37 Brooks Range

The Brooks Range the northernmost mountain groupin Alaska extends for nearly 1000 km in an eastndashwestdirection from the Yukon Territory CanadandashAlaska bor-der on the east to the Chukchi Sea on the west TheBrooks Range forms the drainage divide between theArctic Slope to the north and the Kobuk and YukonRivers to the south The Brooks Range contains about adozen named generally eastndashwest-trending contiguousmountain ranges Glaciers exist within the eastern andcentral Brooks Range spanning a distance of about650 km They are found in the Romanzof Mountains theFranklin Mountains the Philip Smith Mountains theEndicott Mountains and the Schwatka Mountains

The largest glaciers and the greatest concentration ofice are located in the eastern ranges Because the BrooksRange lies wholly north of the Arctic Circle glaciers aregenerally classified as sub-polar Most glaciers are insteep cirques with a northern exposure Two of the threehighest peaks in the Brooks RangeMount Isto (2761m)and Mount Michelson (2699 m) are in the RomanzofMountains Mount Chamberlin (2750 m) the secondhighest peak is in the Franklin Mountains A recentinventory of Brooks Range glaciers by the USGS(Suzanne Brown personal communication 1992) iden-tified 1001 glaciers with a total area of 723 km2

The 105-km-long Romanzof Mountains have aglacier-covered area of about 260 km2 contain at least188 glaciers (Evans 1977) at least four of which havelengths of 5 km or more Wendler (1969) determined thatno glacier ice existed below an elevations of 1500 m andthat at least 66 of the glaciers are on north-facing slopesTwo 83-km-long Okpilak Glacier and 76-km-longMcCall Glacier provide significant information about20th century glacier fluctuations and related changes

r (A) is asim 10 km by 20 km portion of a June 9 2001 ASTER Level 1Bwing the lower part of Bear Glacier and adjacent Resurrection Bay (RB)uring the 1990s Bear Glacier began to retreat rapidly through the loss ofas disarticulation Aialik Bay (AB) is in the upper left part of the image An of Bear Glaciers terminus as shown in (B) (B) is an August 6 2005Between June 2001 and August 2005 the glacier retreated nearly 3 kmseen here The largest pieces are N300 m in maximum dimension


Okpilak Glacier photographed by Leffingwell in1907 (Hamilton 1965) descends from an unnamed2435-m-high mountain about 18 km south of MountMichelson In 1958 Sable (1960) examined a number ofglaciers in the Romanzof Mountains and revisitedseveral photographic sites occupied by Leffingwell atOkpilak Glacier Comparative photographs documentthat the glacier retreated more than 300 m in the inter-vening 51 years Sable (1960) reports that in 1956ndash1958 Okpilak Glaciers lateral moraines were 45 m to635 m above the edges of the glacier In 1907 theyranged from being level to 6m above the ice Sable foundthat the average thinning in the lower 23 km of theglacier was sim 45 m and the mean rate was sim 09 myrHence Okpilak Glacier had thinned from 33m to 695 m(065ndash135 myr) between 1907 and 1958 Sable alsofound that the ratio of ice lost to thinning versus the icelost by recession of the terminus was roughly at least251 Sable (1960) further states that ldquoAll the smallerglaciers in the vicinity of Okpilak Glacier for whichphotographic information from 1907 and 1958 can becompared show evidence of marked recent recessionand thinningrdquo Significant retreat has continued to thepresent (Matt Nolan December 2004 University ofAlaska Fairbanks personal communication)

During the lsquoLandsat Baseline Decadersquo all BrooksRange glaciers were thinning and retreating Theseconclusions are based on published field descriptionsand a comparison by the author of the size and number ofglaciers shown on pre-lsquoLandsat Baseline Decadersquo USGStopographic maps and 1982 AHAP photography from theend of the baseline period Limited information is availableabout behavior at the end of the 20th century and into theearly 21st century However every glacier describedshowed significant evidence of thinning and retreat

38 Aleutian Range

The Aleutian Range extends northeastndashsouthwestalong the spine and southeast side of the Alaska Peninsulafor nearly 1000 km The range contains more than 30glaciers with lengths of 8 km or more one BlockadeGlacier is 44 km long Glaciers cover an area that exceeds2600 km2 (Molnia 1982) During the lsquoLandsat BaselineDecadersquo all of the larger valley glaciers in the AleutianRange were stagnating thinning andor retreatingBrabets et al (2004) examined a number of smallerglaciers in the Tlikakila River Basin of Lake ClarkNational Park and Preserve and found a complex patternof advance and retreat in adjacent glaciers They analyzed86 small unnamed glaciers of which 64 were mapped in1957 photographed in 1978 and imaged by Landsat 7 in

1999 Of the 64 between 1957 and 1978 21 advanced(33) 8 were stable (12) and 35 retreated (55)Between 1978 and 1999 7 advanced (11) 3 were stable(5) and 54 retreated (84) The average terminusadvanceretreat rate increased from a retreat of 4 myr inthe 1957ndash1978 period to a retreat of 14 myr between1978 and 1999 Nearby the three largest glaciers in thearea retreated during the period between 1957 and 2001Tanaina Glacier retreated 1210 m (31 myr) Glacier ForkGlacier (Fig 17) retreated 587 m (133 myr) and NorthFork Glacier retreated 454 m (103 myr)

At the end of the 20th century and into the early 21stcentury all of the larger valley and outlet glaciers in theAleutian Range continued to thin andor retreat whileseveral of the smaller Tlikakila River Basin glaciers mayhave continued to advance (Brabets et al 2004) Whenobserved by the author in 2000 Tuxedni Glaciershowed some evidence of a recent terminus advanceHowever trimlines and abandoned moraines documen-ted a long-term history of retreat and thinning

The 1912 eruption of Mount Katmai melted andbeheaded a number of summit and flank glaciers (Griggs1992) Following the eruption two small glaciers formedwithin the crater on the talus beneath the crater rim Theycontinued to exist throughout the baseline period and intothe early 21st century Similarly following the 1989ndash1990 eruption of Mount Redoubt snow and glacier icehave reformed in its crater replacing snow and ice meltedduring the eruption

39 Aleutian Islands

The Aleutian Island chain the 1900-km-long islandarc which separates the Pacific Ocean from the BeringSea extends westward from False Pass at the westernend of the Alaska Peninsula to longitudesim 172deg E northof eastern Russia The islands support 57 volcanoes ofwhich 27 are active At least 10 islands in the eastern andcentral part of the arc (Unimak Akutan UnalaskaUmnak Yunaska Atka Great Sitkin Tanaga Gareloiand Kiska Islands) had glaciers when topographicallymapped All of the mapped glaciers descended from thesummits of active or dormant volcanoes extending intocalderas or flowing down their flanks All headed atelevations N1200 m

During the lsquoLandsat Baseline Decadersquo the AleutianIslands had a glacier-covered area of b3000 km2Limited information exists about the behavior of theseglaciers during the ldquoBaselinerdquo or at the end of the 20thcentury and into the early 21st century However basedon their small size low elevation and generallysoutherly location in an area with significant late 20th

Fig 17 A 24 km by 33 km portion of the Lake Clark National Park 25-m resolution 1250000-scale Satellite Image Map produced by Michael DFleming from Landsat 7 imagery collected on September 6 1999 (Fleming 2000) Shown is part of the Tlikakila River (TR) Basin an area where anumber of small glaciers have recently been advancing Between 1978 and 1999 Glacier Fork Glacier (GF) the large glacier in the center of theimage retreated 587 m retreating at an average rate of 133 myr


century temperature increases it is likely that they havecontinued to thin and retreat Some may have meltedaway

310 Talkeetna Mountains

The 160-km-long by 130-km-wide Talkeetna Moun-tains have their long axis oriented in a northndashsouthdirection Many peaks have summit elevations N2000 mthe highest an unnamed peak reaches an elevation of2550 m Photographs of glaciers in the TalkeetnaMountains taken by Stephen Capps between 1913 and1917 show many retreating glaciers This is a trend thathas continued through the early 21st century Comparingaerial photographs taken by the author with Cappsphotographs it can be seen that an unnamed glacier at thehead of Iron Creek informally named Iron Creek Glacierretreatedsim 4 km between August 1917 and August 2000Collins (1971) states that ldquoIt can reasonably be deducedthat general recession has been the rule here in recentdecades and that climatic changes have caused asignificant rise in the lower limit at which accumulationcan take place At present this lower limit of accumulationseems to be generally higher than 1850 mrdquo

When mapped between 1951 and 1954 more than100 glaciers were located on the southwestern flank ofthe mountains generally heading at elevations above1800 m Seven had lengths of more than 8 km Thelongest an unnamed glacier informally named SouthSheep River Glacier (175 km long with an area of

sim 75 km2) has been retreating since first mappedChickaloon Glacier (145 km long with an area of32 km2) and Talkeetna Glacier (116 km long with anarea of 33 km2) both have retreating termini that werecovered with thick ablation moraines Observations bythe author suggest that these glaciers have lost as much as5 km of their lengths since 1951ndash1954

McCauley (1958) made planimetric measurements ofall of the glaciers in the Talkeetna Mountains usingUSGS 163360-scale topographic maps prepared be-tween 1948 and 1958 He calculated that the totalglacier-covered area was about 300 km2 The sevenlargest glaciers had a cumulative area of 212 km2accounting for sim 2 3 of the total area These sevenglaciers had termini elevations at between 1460 m and885 m Recent observations by the author show thatevery one of these glaciers has retreated some more than3 km and suggest that the Talkeetna mountains have lostas much as 20 of its glacier coverage since 1948ndash1958

Limited revisions made in 1983 by the USGS to the1954 Talkeetna Mountains 1250000-scale topographicmap based on aerial photography obtained in 19781980 and 1981 show that at least 50 glaciers east of theTalkeetna and Chickaloon Rivers either decreased signi-ficantly in area or completely melted away Similarlyalmost all of the large glaciers west of the two riversshow retreat and shrinkage An aerial survey by theauthor on 31 August 2000 of the entire glacier-coveredTalkeetna Mountains documented that all of its valleyglaciers were conspicuously thinning and retreating


During the lsquoLandsat Baseline Decadersquo the TalkeetnaMountains had a glacier-covered area of b300 km2 Allevidence available suggests that the glaciers of theTalkeetna Mountains were thinning retreating andorstagnating These conclusions are based on a comparisonof the size and number of glaciers shown on topographicmaps made from 1948ndash1952 data and AHAP photog-raphy from the middle of the baseline period (1977) andjust after the ldquoBaselinerdquo interval (1983) When observedat the end of the twentieth century (31 August 2000)every glacier examined showed significant evidence ofthinning and retreat Many smaller glaciers had com-pletely disappeared

311 Ahklun and Wood River Mountains

The Ahklun and Wood River Mountains of south-western Alaska have maximum elevations of sim 1500 mThey are a northeast- to southwest-trending mountainrange with a length ofsim 160 km and a width ofsim 50 kmextending fromBristol Bay to Chikuminuk Lake Manley(William Manley University of Colorado personalcommunication December 2000) examined all 106glaciers that exist in the area and quantified 32 differentparameters for these glaciers He found that the totalglacier-covered area was sim 60 km2 and that individualglaciers ranged in area from 005 km2 to 64 km2 with amedian area of 026 km2 They ranged in averageelevation from 581 m to 1176 m with a median elevationof 937 m ranged in length from 025 km to 438 km withamedian length of 061 km ranged inwidth from017 kmto 297 kmwith amedianwidth of 072 km and ranged inperimeter from 10 km to 238 km with a medianperimeter of 26 km The equilibrium line altitudes(ELAs) ranged from 545 m to 1155 m averaging 929 mand displayed high local variability

Chikuminuk Glacier the longest glacier in the WoodRiver Mountains was mapped during the InternationalGeophysical Year (American Geographical Society(AGS) 1960) At that time it was 55-km long 10-km wide had an area of 577 km2 and was retreatingMore than 75 of the glacier was located at elevationsabove sim 1000 m When photographed in 1957 theterminus region exhibited much evidence of rapidretreat The entire surface of the glacier was bare icewith only a very small accumulation area Elevatedtrimline positions indicated that Chikuminuk Glacierwas thinning On 11 May 1996 Chikuminuk Glacierwas resurveyed with a geodetic airborne laser altimetersystem (Sapiano et al 1998) Interpretation of altimeterprofiles show that the terminus had retreated by 830 mduring the 39 years between surveys an average annual

retreat rate of 212 myr the glaciers area had decreasedby sim 9 (from 577 km2 in 1957 to 533 km2 in 1996)Of the 9 glaciers mapped during the IGY the retreat rateof the terminus of Chikuminuk Glacier was the greatestAt an elevation of sim 480 m during the 39 yr periodbetween surveys the glacier thinned as much assim 42 mAbove an elevation of sim 1075 m the glacier thickenedby an average of sim 10 m Sapiano et al (1998) state thata comparison of 1957 and 1996 volumes suggests thetotal volume of the glacier increased by 8times106 m3however because of differences in methods there is alarge uncertainty in this number

With the exception of Chikuminuk Glacier lack ofrecent information makes it difficult to accurately deter-mine the recent health of other Wood River Mountainsglaciers However based on 1984 photography theglaciers near Mount Waskey have actively thinned andretreated during the lsquoLandsat Baseline Decadersquo

312 Alexander Archipelago

Glaciers are shown in mountainous areas on mid-20thcentury USGS 1250000-scale topographic maps on sixof the islands of the Archipelago Revillagigedo IslandPrince of Wales Island Kupreanof Island BaranofIsland Chichagof Island and Admiralty Island Manyof these glaciers were photographed from the air duringthe late 1920s During the lsquoLandsat Baseline Decadersquothe Alexander Archipelago had a glacier-covered area ofb150 km2 Most glaciers were located on BaranofIsland Most glaciers were very small with areas lessthan 1 km2 All of the glaciers in the AlexanderArchipelago were thinning and retreating Aerial obser-vations by the author between 1999 and 2001 documentthat by the end of the 20th century many of these smallerglaciers may have melted away

313 Kodiak Island

Kodiak Island is located in the western Gulf of Alaskasouth of Cook Inlet and east of Shelikof Strait It has alength of about 160 km and a maximum width of nearly100 km Kodiak Island is the largest island in Alaska TheUSGS Kodiak Alaska 1250000-scale TopographicMap (USGS 1952) based on 1948ndash1952 observationsand photography shows more than 40 cirque glaciersmostly in a narrow upland region located on the moun-tainous backbone of the island between Koniag Peak(1362 m) to the south and Mount Glottof (1343 m) to thenorth and in adjacent drainagesWhenmapped the largestglacier Koniag Glacier the only named glacier on theisland was about 25 km in length It descended to


elevations b500 m One cluster of five glaciers occurredsim 12 km southwest of Koniag Peak at the head of anunnamed tributary to Uyak Bay An isolated unnamed1 km-long-glacier the southernmost and westernmostglacier on the island was located on the west side of anunnamed 1040 m-high peak sim 32 km southwest ofKoniag Peak and 6 km north of Deadman Bay

During the lsquoLandsat Baseline DecadersquoKodiak Islandhad a glacier-covered area of b100 km2 All of theglaciers of Kodiak Island were thinning and retreatingThis is based on a comparison of the size and number ofglaciers shown on Kodiaks USGS topographic mapsmade from 1948ndash1952 data and AHAP photographyfrom the middle of the baseline period (1977ndash1978) Noinformation exists about the behavior of these glaciers atthe end of the 20th century and into the early 21stcentury However based on their small size low eleva-tion and location on an island experiencing a significanttemperature increase surrounded by temperate oceanwater it is likely that they have continued to thin andretreat Some may have melted away

314 Kigluaik Mountains

The only glaciers on the Seward Peninsula arelocated in the 65 km-long eastndashwest trending KigluaikMountains There as recently as 1986 3 glaciers existedon 1437-m-high Mount Osborn and adjacent peaksabout 50 km north of Nome Glaciers of the KigluaikMountains were investigated by Brooks in 1900(Brooks 1901) Henshaw and Parker in 1909 (Henshawand Parker 1913) and Kaufman and his students in thelate 1980s (Kaufman et al 1989 Calkin et al 1998)These investigations document that glaciers existed inthe Kigluaik Mountains through the late 1980s and thatduring the 20th century several glaciers completelydisappeared When last observed the three remainingglaciers Grand Central Glacier Thrush Glacier andPhalarope Glacier had a collective area of significantlyless than 3 km2 and were decreasing in area and length

4 Discussion

As is described above the general thinning andretreat of lower-elevation temperate glaciers is one ofthe most visible manifestations of the Post-LIA responseof Alaskan glaciers to changing regional climate As theregional summaries of Alaskan glacier behavior pre-sented here document most Alaskan mountain glaciersat lower elevations are thinning andor retreating inresponse to a significant Post-LIA regional warming Infact of the glaciers described in the Alaska chapter of

the Satellite Image Atlas of the Glaciers of the World(Molnia in press) more than 98 are currently thinningandor retreating

Of those lower-elevation glaciers that are currentlyadvancing with the exception of South Crillon Glacieran advancing lake-terminating glacier and the small-advancing glaciers in the Aleutian Range reported byBrabets et al (2004) all are marine tidewater or formertidewater glaciers If fact in 2005 10 tidewater orformer-tidewater glaciers were advancing From west toeast they are Anchor Ogive HarvardMeares HubbardLituya North Crillon Lamplugh Johns Hopkins andTakuGlaciers However since the late 19th centurymorethan 50 glaciers have retreated from tidewater to theterrestrial environment Some have disappeared

As has also been shown every Alaskan glacier has itsown complex history and behavior There is both localand regional variability For example many southeastAlaskan glaciers such as most of the glaciers of theGlacier Bay and the Lynn Canal areas began to retreat asearly as the mid-18th century some more than a centurybefore the advent of measurable air temperature changewhile others in the same location advanced during thatentire period

Essentially all Alaskan mountain glaciers are tem-perate meaning that meltwater exists in on or under theglacier for part if not all of the year Globally temperatemountain glaciers are excellent indicators of climatechange and are shrinking on all continents which hostthem Hence small changes in temperature and precip-itation do have a significant impact on the health of theseglaciers Ongoing glacier melting is and will continue tosubstantially reduce the length area thickness andvolume of Earths temperate mountain glaciers AsAlaskan glaciers melt their meltwaters flow into theGulf of Alaska and the Bering Chukchi and BeaufortSeas contributing to sea level rise

Many investigations have examined the role thattemperate glaciers play in present and future sea-levelchange with most of the attention on the last five decadesof the twentieth century (NRC 1977 1983 Meier 1984NRC 1985 1990 Meier 1990 Dyurgerov and Meier1997ab Meier 1998 Dyurgerov andMeier 1999 2000Bahr and Meier 2000 Dyurgerov and Dwyer 2000Arendt et al 2002 Meier and Dyurgerov 2002 MeierandWahr 2002) Nearly all of these reports state that if allthe remaining non-polar (temperate) glacier ice were tomelt a sea-level rise ofb 1mwould result Of thesim 4ofEarths land ice that is made up of mountain glaciersAlaskan glaciers cover b110th or b04

Meier (1984) documented that the glaciers of theAlaskan coastal region may contribute N1 3 of the total


meltwater entering the global ocean As current climatemodels predict future temperature increases theseglaciers may make even larger contributions to futurerising sea level To quantify the role of Alaskan glaciersto global sea-level change Arendt et al (2002)synthesized the results of laser altimeter thicknesschange studies of 67 glaciers in Alaska and adjacentCanada The glaciers they investigated have an area ofsim 18times103 km2 and represent sim 20 of the glacier-covered area of Alaska and adjacent Canada Theirsample included a dozen tidewater calving glaciersnearly a half-dozen lacustrine terminating glaciers andsim 50 land-terminating glaciers Six were surgingglaciers Glaciers they investigated are located in nineof the fourteen regions described in this paper None ofthe glaciers they investigated were located in theTalkeetna Mountains Kigluaik Mountains AlexanderArchipelago Kodiak Island or Aleutian Islands Theyextrapolated their measured thickness changes withineach geographic region of Alaska and Canada investi-gated to all unmeasured glaciers in that region toquantify estimates of the contribution of lsquoAlaskanrsquoglaciers to rising sea level As they define it lsquoglaciers inAlaska and neighboring Canadarsquo cover an area ofsim 90000 km2 or sim 13 of Earths mountain glacierarea They estimate the total annual volume change ofAlaska glaciers expressed as water equivalent to beminus52 plusmn 15 km3yr for the period from sim 1950 to 1993and minus96 plusmn 35 km3yr for the post-1993 period Thesevolumes are equivalent to a rise in sea level of 014 plusmn004 mmyr during the early period and 027 plusmn 1 mmyrduring the later period With respect to thickness changethey report that during both periods most glaciers hadnegative thickness changes indicating significant sur-face lowering During the recent period glacier thinningwas more than twice as much (minus18 myr) as thatmeasured for the same glaciers during the early period(minus07 myr)

The significance of the reported yield of Alaskanglaciers to global sea level can be seen in a comparisonwithsimilar data fromGreenlandKrabill et al (2000) report thatanalysis of aircraft laser altimeter surveys over northernGreenland conducted in 1994 and 1999 indicates a netloss of sim 51 km3yr of ice per year from the entireGreenland ice sheet They state that this is sufficient to raisesea level by 013 mmyr a quantity that is sim 7 of theobserved rise The estimated annual volume loss during therecent period from Alaska 96 plusmn 5 km3yr (Arendt et al2002) is nearly twice that estimated for the entireGreenlandIce Sheet during the same period

On a different note the global baseline of Landsat 12 and 3 glacier information that is presented in the Sa-

tellite Image Atlas of the Glaciers of the World seriesrepresents one of the most significant compilations ofcryospheric information in existence However asKargel et al (2005) show technological advancementspermit the updating and expansion of this Landsat base-line with higher resolution more sophisticated method-ologies such as those employed by the Global Land IceMeasurements from Space (GLIMS) international con-sortium Unlike the retrospective approach applied bythe Satellite Image Atlas of the Glaciers of the World theGLIMS consortium actively acquires satellite images ofthe worlds glaciers analyzes them for glacier extent andchanges and assess change data for causes andimplications for people and the environment As Kargelet al (2005) point out although GLIMS is making use ofmultiple remote-sensing systems ASTER (AdvancedSpaceborne Thermal Emission and Reflection Radiom-eter) is optimized for a variety of necessary observationsincluding mapping of glacier boundaries and surficialmaterials tracking of surface dynamics such as flowvector fields and monitoring the development ofsupraglacial lakes Software developed by the GLIMSconsortium is designed to map clean-ice and debris-covered glaciers classify terrain emphasizing snow icewater and admixtures of ice with rock debris performmulti-temporal change analysis visualize images andderived data and interpret and archive derived data Aglobal glacier database has been designed at the NationalSnow and Ice Data Center (NSIDC Boulder Colorado)with parameters that are compatible with and expandedfrom those of the World Glacier Inventory (WGI) of theWorld Glacier Monitoring Service (WGMS ZurichSwitzerland)

5 Conclusions

This presentation has summarized the aerial extentand distribution of Alaskas glaciers during the lsquoLandsatBaseline Decadersquo and where possible both retrospec-tively and prospectively as well This informationalbaseline can be used by present- and future-researchersto document change in the number length and area ofAlaskan glaciers The abundant and diverse datapresented here clearly document that the glaciers ofAlaska are dynamic and that many are rapidly changingwith most at lower elevations thinning andor retreatingExamples of the dynamic behavior of many Alaskanglaciers are presented ranging from calving glaciers thathave receded a kilometer or more in just a few years tosurging glaciers that have advanced several kilometersduring a surge Through the use of retrospective andprospective data this presentation has also shown many


examples of the dynamic natural behavior displayed byglaciers throughout Alaska

Key findings includeEvery mountain range and island group investigated

is characterized by significant glacier retreat thinningandor stagnation especially at lower elevations

All but a few glaciers that descend below an ele-vation of sim 1500 m are thinning andor retreating

Nearly all of the larger currently advancing glaciersare tidewater or former tidewater glaciers

At some locations glaciers have completely dis-appeared during the 20th century In some areas retreatthat started as early as the early 18th century is con-tinuing into the 21st century

At some locations retreat is resulting in the numberof glaciers actually increasing but the volume and areaof ice decreasing

Glaciers at higher elevations show little or no changeOf the nearly 700 named Alaskan glaciers approx-

imately a dozen are currently advancing

References

ACIA (Arctic Climate Impact Assessment) 2004 The Impacts of aWarming Arctic The Arctic Climate Impact Assessment Chapter2- Arctic Climate Past and Present Cambridge University Presspp 1ndash60

Adalgeirsdottir G Echelmeyer KA Harrison WD 1998Elevation and volume changes on the Harding Icefield AlaskaJournal of Glaciology 44 570ndash582

Alaska Climate Research Center 2005 Temperature change in Alaska1949ndash2001 httpclimategialaskaeduClimTrendsChange4903Changehtml

American Geographical Society 1960 Nine glacier maps Northwest-ern North America American Geographical Society SpecialPublication 34 37 pp 9 plates

Arendt AA Echelmeyer KA Harrison WD Lingle CSValentine VB 2002 Rapid wastage of Alaska glaciers andtheir contribution to rising sea level Science 297 382ndash389

Bahr DB Meier MF 2000 Snow patch and glacier sizedistribution Water Resources Research 36 (2) 495ndash501

Barclay DJ Wiles GC Calkin PC 1999 A 1119-year-tree-widthchronology from western Prince William Sound Alaska TheHolocene 9 79ndash84

Barclay DJ Calkin PE Wiles GC 2001 Holocene history ofHubbard Glacier in Yakutat Bay and Russell Fiord southernAlaska GSA Bulletin 113 (3) 388ndash402

Bates RL Jackson JA 1987 Glossary of Geology Third EditionAmerican Geological Institute Alexandria Virginia

Benson CS 1968 Glaciological studies on Mount Wrangell AlaskaArctic 21 (3) 128ndash152

Benson CS Follett AB 1986 Application of photogrammetry tothe study of volcanondashglacier interactions on Mount WrangellAlaska Photogrammetric Engineering and Remote Sensing 52813ndash827

Benson CS Motyka RJ 1975 Recent glaciological and volcano-logical studies at the summit of Mt Wrangell Alaska EOS 56 (2)1073

Benson CS Motyka RJ 1978 GlacierndashVolcano Interactions onMount Wrangell Alaska Annual Report 1977ndash78 University ofAlaska Geophysical Institute Fairbanks Alaska pp 1ndash25

Benson CS Bingham DK Wharton GB 1975 Glaciological andvolcanological studies at the summit of Mt Wrangell Snow andIce Symposium mdash Proceedings XV General Assembly IUGGMoscow Symposium August 1971 IAHS-AISH Publicationvol 104 pp 95ndash98

Brabets TP March RP Trabant DC 2004 Glacial history andrunoff components of the Tlikakila River Basin Lake ClarkNational Park and Preserve Alaska USGS Scientific InvestigationReport 2004ndash5057

Bradley RS 1990 Holocene paleoclimatology of the QueenElizabeth Islands Canadian high Arctic Quaternary ScienceReviews 9 365ndash384

Bradley RS Jones PD 1993 lsquoLittle Ice Agersquo summer temperaturevariations their nature and relevance to recent global warmingtrends The Holocene 3 367ndash376

Brooks AH 1901 Reconnaissances in the CapeNome andNortonBayRegions Alaska in 1900 USGS Special Publication pp 43ndash45

Calkin PE Kaufman DS Przyble BJ Whitford WB Peck BJ1998 Glacier regimes periglacial landforms and Holoceneclimate change in the Kigluaik Mountains Seward PeninsulaAlaska USA Arctic and Alpine Research 30 154ndash165

Calkin PE Wiles GC Barclay DJ 2001 Holocene coastalglaciation of Alaska Quaternary Science Reviews 20 449ndash461

Capps SR 1910 Glaciation on the north side of the WrangellMountains Journal of Geology 18 33ndash57

Carlson PR Bruns TRMolniaBF SchwabWC 1982 Submarinevalleys in the northeastern Gulf of Alaska evidence for glaciation onthe continental shelf Marine Geology 47 217ndash242

Clarke GK Schmok JC Ommanney CSL Collins SG 1986Characteristics of surge-type glaciers Journal of GeophysicalResearch 91 7165ndash7180

Clarke GK Cross GM Benson CS 1989 Radar imaging ofglaciovolcanic stratigraphy Mount Wrangell Caldera Alaskainterpretation model and results Journal of Geophysical Research94 7237ndash7249

Collins SG 1975 Glaciers of the Talkeetna Mountains Alaska InField WO (Ed) Mountain Glaciers of the Northern HemisphereUS Army Corps of Engineers vol 2 Cold Regions Research andEngineering Laboratory Hanover New Hampshire pp 543ndash548

Crowley TJ Lowery T 2000 How warm was the medieval warmperiod Ambio 29 51ndash54

Davidson G 1904 The glaciers of Alaska that are shown on Russiancharts or mentioned in older narratives Transactions andProceedings of the Geographical Society of the Pacific III 1ndash98

Denton GH Field WO 1975 Glaciers of the Alaska Range InField WO (Ed) Mountain Glaciers of the Northern HemisphereUS Army Corps of Engineers vol 2 Cold Regions Research andEngineering Laboratory Hanover New Hampshire pp 573ndash620

Dyurgerov MB Meier MF 1997a Mass balance of mountain andsubpolar glaciers a new assessment for 1961ndash1990 Arctic andAlpine Research 29 379ndash391

Dyurgerov MB Meier MF 1997b Year-to-year fluctuations ofglobal mass balance of small glaciers and their contribution to sealevel changes Arctic and Alpine Research 29 392ndash402

Dyurgerov MB Dwyer J 2000 The steepening of glacier massbalance gradients with Northern Hemisphere warming Zeitschriftfur Gletscherkunde and Glazialgeologie 36 107ndash118

Dyurgerov MB Meier MF 1999 Analysis of winter and summermass balances Geografiska Annaler 81A (4) 541ndash554


Dyurgerov MB Meier MF 2000 Twentieth century climatechange evidence from small glaciers Proceedings of the NationalAcademy of Sciences 97 (4) 1406ndash1411

Echelmeyer KA Motyka RJ 1997 LeConte Glacier Alaskasurface elevation changes and calving retreat In van der Veen GJ(Ed) Calving Glaciers Report of a Workshop February 28ndashMarch 2 1997 BPRC Report no vol 15 Byrd Polar ResearchCenter The Ohio State University Columbus Ohio pp 67ndash70

Echelmeyer KA Harrison WD Larsen CF Sapiano J MitchellJE DeMallie J Rabus B Adalgeirsdottir G Sombardier L1996 Airborne surface profiling of glaciers a case-study inAlaska Journal of Glaciology 42 538ndash547

Evans IC 1977World-wide variations in the direction and concentrationof cirque and glacier aspects Geografiska Annaler 59A 151ndash175

Field WO 1932 The glaciers of the northern part of Prince WilliamSound Alaska Geographical Review 22 361ndash388

Field WO 1937 Observations of Alaskan coastal glaciers in 1935Geographical Review 27 63ndash81

Field WO (Ed) 1975a Mountain Glaciers of the NorthernHemisphere Hanover New Hampshire US Army Corps ofEngineers vol 2 Cold Regions Research and EngineeringLaboratory Hanover New Hampshire

Field WO 1975b Glaciers of the Chugach Mountains In Field WO(Ed) Mountain Glaciers of the Northern Hemisphere US ArmyCorps of Engineers vol 2 Cold Regions Research and EngineeringLaboratory Hanover New Hampshire pp 299ndash492

FieldWO 1975c Glaciers of the Kenai Mountains Alaska In FieldWO (Ed) Mountain Glaciers of the Northern Hemisphere USArmy Corps of Engineers vol 2 Cold Regions Research andEngineering Laboratory Hanover New Hampshire pp 493ndash541

FieldWO 1975dGlaciers of the coastmountains boundary ranges InField WO (Ed) Mountain Glaciers of the Northern HemisphereUS Army Corps of Engineers vol 2 Cold Regions Research andEngineering Laboratory Hanover New Hampshire pp 11ndash141

FieldWO Collins SG 1975Glaciers of the St EliasMountains InField WO (Ed) Mountain Glaciers of the Northern HemisphereUS Army Corps of Engineers vol 2 Cold Regions Research andEngineering Laboratory Hanover New Hampshire pp 143ndash297

Fleming MD 2000 Satellite image map of Lake Clark NationalPark 25-m resolution 1250000-scale produced from Landsat 7imagery collected on September 6 1999 1 sheet

Fountain AG Krimmel RM Trabant DC 1997 A Strategy forMonitoring Glaciers USGS Circular vol 1132 19 pp

Gilbert GK 1904 Alaskamdash glaciers and glaciation Harriman AlaskaExpedition with cooperation of theWashington Academy of SciencesDoubleday Page and Company New York volume III 231 pp

Grant US Higgins DF 1913 Coastal glaciers of Prince WilliamSound and the Kenai Peninsula Alaska USGS Bulletin vol 52675 pp 2 plates

Griggs RF 1922 The Valley of the Ten Thousand Smokes TheNational Geographic Society Washington DC 241 pp

Grunblatt J Bennett J 2004 Landsat image mosaic of Glacier BayNational Park and Preserve scale 1155000 image prepared fromLandsat 7 TM imagery collected between August 1 1999 andAugust 10 National Park Service Alaska Landover MappingProgram 1 sheet

Grossman PY Easterling DA 1994 Variability and trends ofprecipitation and snowfall over the United States and CanadaJournal of Climate 7 184ndash205

Hall DK Benson CS Field WO 1995 Changes in glaciers inGlacier Bay Alaska using ground and satellite measurementsPhysical Geography 16 27ndash41

Hamilton TD 1965 Comparative glacier photographs from northernAlaska Journal of Glaciology 5 (40) 479ndash487

Henshaw FF Parker GL 1913 Surface water supply of theSeward Peninsula Alaska USGS Water Supply Paper 314152ndash165

Hunter LE Motyka RJ Echelmeyer Keith 2001 Sedimentationand denudation rates of a tidewater glacier eroding batholithicbedrock LeConte Glacier Alaska Eos Transactions AGU 82(47) Fall Meeting Supplement Abstract IP52A-0747

Kargel JS Abrams MJ Bishop MP Bush A Hamilton GJiskoot H Kaumlaumlb A Kieffer HH Lee EM Paul F Rau FRaup B Shroder JF Soltesz D Stainforth D Stearns LWessels R 2005Multispectral imaging contributions to global landice measurements from space Remote Sensing of Environment 99(1ndash2) 187ndash219

KaufmanDS Calkin PEWhitfordW Przyble BJ Hopkins DMPeck BJ Nelson RE 1989 Surficial geologic map of theKigluaik Mountains area Seward Peninsula Alaska USGSMiscellaneous Field Studies Map 2074

Krabill W Abdalati W Frederick E Manizade S Martin CSonntag J Swift R Thomas R Wright W Yungel J 2000Greenland Ice Sheet high-elevation balance and peripheralthinning Science 289 428ndash430

Krimmel RM 2001 Photogrammetric data set 1957ndash2000 andbathymetric measurements for Columbia Glacier Alaska USGSWater-Resources Investigations Report 01-4089 40 pp

Krimmel RM Meier MF 1989 Glaciers and Glaciology of AlaskaField Trip Guide Book T301 28th International GeologicalCongress American Geophysical Union Washington DC

LaPerouse JFG de 1799 Voyage round the world which wasperformed in the years 1785 1786 1787 and 1788 M Milet-Mureau Paris 600 p

Lawrence DB 1950 Glacier fluctuations for six centuries insoutheastern Alaska and its relation to solar activity GeographicalReview 40 191ndash223

Mann ME Bradley RS Hughes MK 1999 Northern Hemi-sphere temperatures during the past millennium inferencesuncertainties and limitations Geophysical Research Letters 26759ndash762

Mayo LR 1978 Identification of unstable glaciers intermediatebetween normal and surging glaciers Academy of Sciences of theUSSR Section of Glaciology of the Soviet GeophysicalCommittee and Institute of Geography Moscow Data ofGlaciological Studies Publication 33 Proceedings (Alma-Ata1976) vol 47ndash55 pp 133ndash135

McCauley C 1958 Glaciers of the TalkeetnaMountains Alaska InField WO (Ed) Geographic Study of Mountain Glaciation inthe Northern Hemisphere vol 2 American Geographic Societypp 2a51ndash2a54

Meier MF 1984 Contribution of small glaciers to global sea levelScience 226 1418ndash1421

Meier MF 1990 Role of land ice in present and future sea-levelchange Geophysics Study Committee of the National ResearchCouncil Commission of Physical Sciences Mathematics andResources (Ed) Sea-level Change National Academy PressWashington DC pp 171ndash184

Meier MF 1998 Monitoring ice sheets ice caps and large glaciersChapter 13 In Haeberli W Hoelzle M Suter S (Eds) Into theSecond Century of Worldwide Glacier Monitoring UNESCO PressParis

Meier MF Dyurgerov MB 2002 Sea level changes how Alaskaaffects the world Science 297 (5580) 350ndash351


Meier MF Wahr J 2002 Sea level is rising mdash do we know whyProceedings of the National Academy of Sciences 99 (10)6524ndash6526

Meier MF Rasmussen LA Post AS Brown CS Sikonia WGBindschadler RA Mayo LR Trabant DC 1980 PredictedTiming of the Disintegration of the Lower Reach of ColumbiaGlacier Alaska USGS Open-File Report 80-582 47 pp

Miller MM 1948 Aerial survey of Alaskan glaciers 1947 Appalachia27 13ndash115

Molnia BF (Ed) 1981 Glacial-Marine Sedimentation PlenumPress New York 844 pp

Molnia BF 1982 Alaskas glaciers Alaska Geographic vol 9 (rev1993) 144 p

Molnia BF in press Glaciers of Alaska with sections on Columbiaand Hubbard tidewater glaciers by Krimmel RM The 1986 and2002 temporary closures of Russell Fiord by the Hubbard Glacierby Molnia BF Trabant DC March RS and Krimmel RMand Geospatial inventory and analysis of glaciers a case study forthe eastern Alaska Range by Manley WF In Williams RS JrFerrigno JG (Eds) Satellite Image Atlas of Glaciers of theWorld USGS Professional Paper 1386-K 705 pp

Molnia BF 2000 Glaciers of Alaska Alaska Geographic vol 28(2) 112 pp

Molnia BF Carlson PR 1975 Base map of the Northern Gulf ofAlaska USGS Open File Report 75ndash506 1 sheet

Molnia BF Post AS 1995 Holocene history of Bering GlacierAlaska a prelude to the 1993ndash1994 surge Physical Geography 1687ndash117

Molnia BF Wheeler MC 1978 Report on the beach dynamicsgeology and oil spill susceptibility of the Gulf of Alaska coastlinein Glacier Bay National Monument mdash Sea Otter Creek to IcyPoint USGS Open File Report 78ndash284 140 pp 1 plate

Motyka RJ Echelmeyer KA Elsberg D 2001 Taku Glacier onthe move again active deformation of proglacial sediments EosTransactions AGU vol 82 (47) Fall Meeting SupplementAbstract IP52A-0745

NRC (Board on Atmospheric Sciences and Climate Commission ofPhysical Sciences Mathematics and Resources) 1983 ChangingClimate Report of the Carbon Dioxide Assessment CommitteeNational Academy Press Washington DC 496 pp

NRC (Geophysics Study Committee of the National ResearchCouncil) 1977 Energy and Climate National Academy PressWashington DC 158 pp

NRC (Ad Hoc Committee on the Relationship between Land Ice anSea Level Committee on Glaciology Polar Research BoardCommission on Physical Sciences Mathematics and Resources)1985 Glaciers Ice Sheets and Sea Level Effects of a CO2-induced Climate Change National Academy Press WashingtonDC 330 pp

NRC (Geophysics Study Committee of the National Research CouncilCommission of Physical Sciences Mathematics and Resources)1990 Sea-level Change National Academy Press WashingtonDC 234 pp

Nolan M Motyka RJ Echelmeyer KA Trabant DC 1995 Ice-thickness measurements of Taku Glacier Alaska USA and theirrelevance to its recent behavior Journal of Glaciology 41541ndash553

Parson EA Carter L Anderson P Wang B Weller G 2000Potential consequences of climate variability and change forAlaska In National Assessment Synthesis Team (US GlobalChange Research Program) Climate change impacts on the UnitedStates the potential consequences of climate variability and

change httpwwwusgcrpgovusgcrpLibrarynationalassess-mentoverviewalaskahtm

Plafker G Miller DJ 1958 Glacial features and surficial deposits ofthe Malaspina District Alaska USGS Miscellaneous GeologicInvestigations Map I-271 1 sheet

Post AS 1960 The exceptional advances of the Muldrow BlackRapids and Susitna Glaciers Journal of Geophysical Research 653703ndash3712

Post AS 1965 Alaskan glaciers recent observations in respect to theearthquake advance theory Science 148 366ndash368

Post AS 1969 Distribution of surging glaciers in western NorthAmerica Journal of Glaciology 8 (53) 229ndash240

Post AS 1975 Preliminary hydrography and historic terminalchanges of Columbia Glacier Alaska USGS HydrologicalInvestigations Atlas 559 3 sheets

Post AS Mayo LR 1971 Glacier dammed lakes and outburstfloods in Alaska USGS Hydrological Investigations Atlas 4553 sheets 10 pp

Post AS Meier MF 1980 A preliminary inventory of Alaskanglaciers Proceedings of the Riederalp World Glacier InventoryWorkshop September 1987 IASH Publication vol 126 pp 45ndash47

Post AS Motyka RJ 1995 Taku and LeConte Glaciers Alaskacalving-speed control of late-Holocene asynchronous advancesand retreats Physical Geography 16 59ndash82

Reid HF 1892 Studies of Muir Glacier Alaska NationalGeographic Magazine 4 19ndash84

Reid HF 1896 Glacier Bay and its glaciers USGS 16th AnnualReport 1894ndash1895 Pt 1 pp 415ndash461

Reyes AV Wiles GC Smith DJ Barclay DJ Allen SJackson S Larocque S Laxton S Lewis D Calkin PEClague JJ 2006 Expansion of alpine glaciers in Pacific NorthAmerica in the first millennium AD Geology 34 57ndash60

Russell IC 1897 Glaciers of North America Ginn and Co Boston210 pp

Sable EG 1960 Recent recession and thinning of Okpilak Glaciernortheastern Alaska Arctic 14 176ndash187

Sapiano JJ Harrison WD Echelmeyer KA 1998 Elevationvolume and terminus changes of nine glaciers in North AmericaJournal of Glaciology 44 119ndash135

Sauber Jeanne Plafker George Molnia BF Bryant MA 2000Crustal deformation associated with glacial fluctuations in theeastern Chugach Mountains Alaska Journal of GeophysicalResearch 105 8055ndash8077

Sturm M 1995 Short-period velocity fluctuations of two glaciers onMt Wrangell Alaska Physical Geography 16 42ndash58

Sturm M Hall DK Benson CS Field WO 1991 Non-climaticcontrol of glacier terminus fluctuations in the Wrangell andChugach Mountains Alaska USA Journal of Glaciology 37248ndash356

Tarr RS Martin L 1910 The National Geographic SocietysAlaskan expedition of 1909 The National Geographic MagazineXXI 1ndash53

Tarr RS Martin L 1914 Alaskan Glacier Studies of the NationalGeographic Society in the Yakutat Bay Prince William Sound andLower Copper River Regions National Geographic SocietyWashington DC 498 pp

Time Magazine 1937 Runaway glacier March 1 1937Trabant DC Krimmel RM 2001 Hubbard Glacier will block the

entrance to Russell Fiord Alaska Eos Transactions AGU vol 82(47) Fall Meeting Supplement Abstract IP52A-0685

USGS 1952 (minor revisions 1982) Kodiak Alaska 1250000-scaletopographic map 1 sheet


USGS 1955 Bradfield Canal AlaskandashCanada 1250000-scaletopographic map 1 sheet

USGS 2004 Glacier temperature summary httpakwaterusgsgovglaciologyall_bmg3glacier_temphtm

Viens RJ 1995 Dynamics and mass balance of temperate tidewatercalving glaciers of southern Alaska Masters Thesis University ofWashington Seattle 149 pp

Wendler Gerd 1969 Characteristics of the glaciation of BrooksRange Alaska Archiv fur Meteorologie Geophysik und Biokli-matologie Serie B 17 85ndash92

Wiles GC Barclay DJ Calkin PC 1999 Tree-ring dated lsquoLittle IceAgersquo histories of maritime glaciers from western Prince WilliamSound Alaska The Holocene 9 163ndash173

Late nineteenth to early twenty-first century behavior of Alaskan glaciers as indicators of cha

Introduction

Alaskan glaciers

Alaskan climate mdash the last millennium

Recent temperature trends

Tidewater glaciers

Surging glaciers

Methods

Results and analyses

Chugach Mountains

Saint Elias Mountains

Alaska Range

Wrangell Mountains

Coast Mountains

Kenai Mountains

Brooks Range

Aleutian Range

Aleutian Islands

Talkeetna Mountains

Ahklun and Wood River Mountains

Alexander Archipelago

Kodiak Island

Kigluaik Mountains

Discussion

Conclusions

References

Fig 1 AVHRR image map showing the location of the 14 glacierized areas of Alaska Current glacier cover for each region based on data presentedin Molnia (in press) is 1) Chugach Mountainsmdash sim 21320 km2 2) Saint Elias Mountainsmdash sim 14300 km2 3) Alaska Rangemdash sim 14000 km2 4)Wrangell Mountainsmdash sim 5300 km2 5) Coast Mountainsmdash sim 7280 km2 6) Kenai Mountainsmdash sim 4810 km2 7) Brooks Rangemdash b1000 km2 8)Aleutian Rangemdashsim 2000 km2 9) Aleutian Islandsmdashsim 2000 km2 10) TalkeetnaMountainsmdashsim 1000 km2 11) AhklunndashWoodRiverMountainsmdashsim 60 km2 12) Alexander Archipelagomdash b100 km2 13) Kodiak Islandmdash b50 km2 and 14) Kigluaik Mountainsmdash b1 km2 AVHRR base figure byMichael Fleming is modified from Molnia 2000


as N55deg19prime and W130deg05prime about 100 km east ofKetchikan to as far southwest as Kiska Island atN52deg05prime and E177deg35prime in the Aleutian Islands to as farnorth as N69deg20prime and W143deg45prime in the Brooks RangeThe number of glaciers is unknown having never beensystematically counted but probably exceeds 100000Most are small upland cirque glaciers Approximately2000 are valley glaciers Of these valley glaciers sim 60(b01 by number) are tidewater glaciers (Viens 1995)Hence by number N999 of Alaskas glaciers areland-based or terrestrial By area tidewater glaciersoccupy sim 27000 km2 or sim 1 3 of the glacier-coveredarea of Alaska

Alaskan glaciers range in elevation from above6000 m to below sea level Most are unnamed Fewerthan 700 glaciers have been officially named by the USBoard on Geographic Names Nearly all of these namedglaciers and about 1000 additional unnamed glaciersdescend below an elevation of sim 1500 m

During the Little Ice Age (LIA) the total glacier-covered area and the number of mountain ranges andislands with glacier cover were significantly larger than

present (Molnia in press) Since then as has been thecase in all of Earths temperate glacier-covered areasthere has been a significant decrease in glacier lengtharea and thickness However the timing magnitudeand complexity of this ldquopost-LIArdquo glacier change ineach of Alaskas 14 glacier-bearing areas have beendifferent To understand these complexities a detailedassessment of each of Alaskas glacier-bearing regionswas prepared as part of the USGS comprehensive Sa-tellite Image Atlas of the Glaciers of the World series(Molnia in press) Key findings from this Atlasassessment are synthesized and succinctly presentedhere specifically to define the late 19th to early 21stcentury behavior of Alaskan glaciers in response to adocumented changing regional climate which is char-acterized by temperature increases at all monitoringstations throughout Alaska As the details presentedhere show although there is a significant thinning oflower-elevation glaciers and retreat of glacier terminithe current behavior of Alaskas glaciers varies signi-ficantly from area to area varies significantly withelevation and is extremely dynamic


































15 Surging glaciers









2 Methods






























































33 Alaska Range


























35 Coast Mountains



























36 Kenai Mountains








37 Brooks Range








38 Aleutian Range





39 Aleutian Islands





















313 Kodiak Island







4 Discussion













5 Conclusions












References






















































































































Introduction

Alaskan glaciers



Tidewater glaciers

Surging glaciers

Methods


Chugach Mountains


Alaska Range

Wrangell Mountains

Coast Mountains

Kenai Mountains

Brooks Range

Aleutian Range

Aleutian Islands

Talkeetna Mountains



Kodiak Island

Kigluaik Mountains

Discussion

Conclusions

References


































15 Surging glaciers









2 Methods






























































33 Alaska Range


























35 Coast Mountains



























36 Kenai Mountains








37 Brooks Range








38 Aleutian Range





39 Aleutian Islands





















313 Kodiak Island







4 Discussion













5 Conclusions












References






















































































































Introduction

Alaskan glaciers



Tidewater glaciers

Surging glaciers

Methods


Chugach Mountains


Alaska Range

Wrangell Mountains

Coast Mountains

Kenai Mountains

Brooks Range

Aleutian Range

Aleutian Islands

Talkeetna Mountains



Kodiak Island

Kigluaik Mountains

Discussion

Conclusions

References





2 Methods







Fig 6 A pair of north-looking photographs of Toboggan Glacier both taken from about the same offshore location Harriman Fiord Prince WilliamSound The pair documents significant changes that have occurred during the 91 years between June 29 1909 and September 4 2000 The 1909photograph by Sidney Paige (A) shows that early in the 20th century Toboggan Glacier was thinning and retreating and was surrounded by a largebedrock barren zone Minimal vegetation existed on the fiord-facing hill slopes By 1909 the terminus appears to have thinned to about 50 of itsformer thickness (1909mdashUSGS Photo Library Photographmdash 31) The 2000 photograph (B) documents the continuing thinning and retreatof Toboggan Glacier The former tributary located on the north (left) side of the glacier has also thinned and retreated significantly Note the extensivevegetation that has developed on the beach and at the glaciers margins (photograph by Bruce F Molnia)























































33 Alaska Range


























35 Coast Mountains



























36 Kenai Mountains








37 Brooks Range








38 Aleutian Range





39 Aleutian Islands





















313 Kodiak Island







4 Discussion













5 Conclusions












References






















































































































Introduction

Alaskan glaciers



Tidewater glaciers

Surging glaciers

Methods


Chugach Mountains


Alaska Range

Wrangell Mountains

Coast Mountains

Kenai Mountains

Brooks Range

Aleutian Range

Aleutian Islands

Talkeetna Mountains



Kodiak Island

Kigluaik Mountains

Discussion

Conclusions

References





























































33 Alaska Range


























35 Coast Mountains



























36 Kenai Mountains








37 Brooks Range








38 Aleutian Range





39 Aleutian Islands





















313 Kodiak Island







4 Discussion













5 Conclusions












References






















































































































Introduction

Alaskan glaciers



Tidewater glaciers

Surging glaciers

Methods


Chugach Mountains


Alaska Range

Wrangell Mountains

Coast Mountains

Kenai Mountains

Brooks Range

Aleutian Range

Aleutian Islands

Talkeetna Mountains



Kodiak Island

Kigluaik Mountains

Discussion

Conclusions

References





















35 Coast Mountains



























36 Kenai Mountains








37 Brooks Range








38 Aleutian Range





39 Aleutian Islands





















313 Kodiak Island







4 Discussion













5 Conclusions












References






















































































































Introduction

Alaskan glaciers



Tidewater glaciers

Surging glaciers

Methods


Chugach Mountains


Alaska Range

Wrangell Mountains

Coast Mountains

Kenai Mountains

Brooks Range

Aleutian Range

Aleutian Islands

Talkeetna Mountains



Kodiak Island

Kigluaik Mountains

Discussion

Conclusions

References






















36 Kenai Mountains








37 Brooks Range








38 Aleutian Range





39 Aleutian Islands





















313 Kodiak Island







4 Discussion













5 Conclusions












References






















































































































Introduction

Alaskan glaciers



Tidewater glaciers

Surging glaciers

Methods


Chugach Mountains


Alaska Range

Wrangell Mountains

Coast Mountains

Kenai Mountains

Brooks Range

Aleutian Range

Aleutian Islands

Talkeetna Mountains



Kodiak Island

Kigluaik Mountains

Discussion

Conclusions

References







37 Brooks Range








38 Aleutian Range





39 Aleutian Islands





















313 Kodiak Island







4 Discussion













5 Conclusions












References






















































































































Introduction

Alaskan glaciers



Tidewater glaciers

Surging glaciers

Methods


Chugach Mountains


Alaska Range

Wrangell Mountains

Coast Mountains

Kenai Mountains

Brooks Range

Aleutian Range

Aleutian Islands

Talkeetna Mountains



Kodiak Island

Kigluaik Mountains

Discussion

Conclusions

References




38 Aleutian Range





39 Aleutian Islands





















313 Kodiak Island







4 Discussion













5 Conclusions












References






















































































































Introduction

Alaskan glaciers



Tidewater glaciers

Surging glaciers

Methods


Chugach Mountains


Alaska Range

Wrangell Mountains

Coast Mountains

Kenai Mountains

Brooks Range

Aleutian Range

Aleutian Islands

Talkeetna Mountains



Kodiak Island

Kigluaik Mountains

Discussion

Conclusions

References



















313 Kodiak Island







4 Discussion













5 Conclusions












References






















































































































Introduction

Alaskan glaciers



Tidewater glaciers

Surging glaciers

Methods


Chugach Mountains


Alaska Range

Wrangell Mountains

Coast Mountains

Kenai Mountains

Brooks Range

Aleutian Range

Aleutian Islands

Talkeetna Mountains



Kodiak Island

Kigluaik Mountains

Discussion

Conclusions

References






4 Discussion













5 Conclusions












References






















































































































Introduction

Alaskan glaciers



Tidewater glaciers

Surging glaciers

Methods


Chugach Mountains


Alaska Range

Wrangell Mountains

Coast Mountains

Kenai Mountains

Brooks Range

Aleutian Range

Aleutian Islands

Talkeetna Mountains



Kodiak Island

Kigluaik Mountains

Discussion

Conclusions

References






5 Conclusions












References






















































































































Introduction

Alaskan glaciers



Tidewater glaciers

Surging glaciers

Methods


Chugach Mountains


Alaska Range

Wrangell Mountains

Coast Mountains

Kenai Mountains

Brooks Range

Aleutian Range

Aleutian Islands

Talkeetna Mountains



Kodiak Island

Kigluaik Mountains

Discussion

Conclusions

References











References






















































































































Introduction

Alaskan glaciers



Tidewater glaciers

Surging glaciers

Methods


Chugach Mountains


Alaska Range

Wrangell Mountains

Coast Mountains

Kenai Mountains

Brooks Range

Aleutian Range

Aleutian Islands

Talkeetna Mountains



Kodiak Island

Kigluaik Mountains

Discussion

Conclusions

References






















































































Introduction

Alaskan glaciers



Tidewater glaciers

Surging glaciers

Methods


Chugach Mountains


Alaska Range

Wrangell Mountains

Coast Mountains

Kenai Mountains

Brooks Range

Aleutian Range

Aleutian Islands

Talkeetna Mountains



Kodiak Island

Kigluaik Mountains

Discussion

Conclusions

References

late nineteenth to early twenty-first century behavior of ... · late nineteenth to early...

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