1/25/08 AK Sea Ice Change & Impacts on Human Activities 1
Sea-ice change around Alaska &Impacts on Human Activities
Hajo EickenGeophysical InstituteUniversity of Alaska Fairbanks,[email protected]
• Introduction• The Arctic sea-ice cover:
Observations & predictions• Alaska sea-ice change• Impacts• Conclusions
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Sea-ice change around Alaska &Impacts on Human Activities
• Introduction• The Arctic sea-ice cover:
Observations &predictions
• Alaska sea-ice change• Impacts• Conclusions
1/25/08 AK Sea Ice Change & Impacts on Human Activities 3
Arctic sea-ice summer extent
• 2007 record sea-ice minimum,almost onequarter less in extent than previousrecord minimum in 2005
• Winter ice extent is decreasing but atmuch slower rate: More seasonal ice!
Sep 16, 2007 nsidc.org
Summer minimummedian ice edge (‘79-’00)
Perennialice ‘07
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The 2007 record minimum Arctic sea-icesummer extent: Possible explanations
(1) Longer-term retreat pattern roughly inline with what is predicted as result ofglobal warming
(2) Thinner, younger, more mobile icemoves & retreats more quickly in summer
(3) Southerly winds brought warm air andmoved ice towards North Pole in 2007
(4) Warm inflow of water through BeringStrait (?)
(5) Warming of water north of Alaska as aresult of thinned & reduced ice covermelts back ice from below in summer (>7feet of summer bottom melt north ofAlaska!)
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The 2007 record minimum Arctic sea-icesummer extent: Possible explanations
(1) Longer-term retreat pattern roughly inline with what is predicted as result ofglobal warming
(2) Thinner, younger, more mobile icemoves & retreats more quickly in summer
(3) Southerly winds brought warm air andmoved ice towards North Pole in 2007
(4) Warm inflow of water through BeringStrait (?)
(5) Warming of water north of Alaska as aresult of thinned & reduced ice covermelts back ice from below in summer (>7feet of summer bottom melt north ofAlaska!)
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The Arctic sea-ice cover: Model projections
Meehl et al., 2007
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The Arctic sea-ice cover: Model projections
• Recent summerreductionssomewhatfaster thanmodels predict
• Severalplausibleexplanations,related to howalbedo, icethickness andother factorsare simulated
Stroeve et al., 2007
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Sea-ice change around Alaska &Impacts on Human Activities
• Introduction• The Arctic sea-ice cover:
Observations & predictions• Alaska sea-ice change• Impacts• Conclusions
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Minimum ice extent anomalies, onset offreezing/melt, freezing/thawing degree-days
• Reduction in summer ice• Beaufort/Chukchi Seas: Later
freeze-up, reduced freezingdegree-days
NSIDC (2007)
Mahoney et al. (2007)
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2007:Record
ice yearin Alaska?
• From June 2007, amount of openwater at record high through Nov
• Barrow air temperature normal inearly summer, above-normal(records broken on 5 days) in latesummer
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Summer ice variability:Regional ice regimevs. Arctic ice regime
• Length of Barrow-Prudhoenavigation season, severityof ice in coastal Chukchi-Beaufort Sea in August-September (computed byNational Ice Center)
• Resolution/accuracy ofremote sensing data
• Interannual & local variability• Summer ice incursions
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Lead occurrence patterns (1993-2004)
• Winds mostlyfrom ENE(Barrow, 1971-2000) or E(Barter Island,1971-1988)
Grounded ice
“Spring” iceConnected network of open water around floes
Leads at edge of
stable extension
Coastal flooding and melting of landfast ice
Flaw leads and polynyas
Arches and arcing leads
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Landfast ice zone
Bottomfast ice
Floatinglandfast ice
Groundedridges (shear/stamukhizone)
Landfast ice extensions
Pack ice
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Seasonal cycle of landfast ice extent• Mean controlled
by bathymetry• Maximum
controlled bypack/landfast iceinteraction(stableextension)
• Minimumcontrolled bybreak-out events
• Iñupiaq iceexperts: Break-outs much morefrequent sinceearly 1990s
Mahoney et al. (2007)
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This study Barry et al. (1979a)
Zone
1
Zone
2
Zone
3
Zone
4
All
zones
Central
Chukchi
Central
Beaufort
MeanDec
01
Oct
25
Nov
04
Nov
9
Nov
7First
Ice*!’ 31.8 9.6 11.4 17.5 16.4
Early
November
Mid
October
First
continuous
fast ice
MeanFeb
23
Jan
22
Jan
28
Jan
27
Feb
01Stable
Ice!’ 41.9 30.1 32.6 34.9 34.1
Feb Jan/Feb
Stable ice
inside of 15
m isobath
MeanJun
04
Jun
11
Jun
04
May
26
Jun
06Break
up!’ 13.9 14.2 13.7 12.6 14.6
Jun 10 Jun 30
First
openings
and
movement
MeanJun
18
Jun
24
Jun
24
Jun
06
Jun
18Ice
Free!’ 12.7 8.4 12.6 10.2 10.4
Jul 05 Aug 01
Nearshore
largely free
of fast ice
*1996-1998 omitted from analysis Mahoney et al. (2007)
1996-2004: E Chuk West Centr East Beauf
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Winter sea-ice break-out events
December 13, 2001: Ice breaksout from stretch of coastlineSW of Barrow past NARL (>15 km)
Barrow
Photo: Craig George
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Multiple rafting withsediment layers in lowersections
Pack-ice/landfast-ice interaction:Have changes in ice circulationand ice thickness resulted indifferent deformation modes(rafting vs. ridging)?
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Ice Push events (ivu)
Fbks Daily News-Miner Jan 25, 2006
Photo: A. Jensen
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Solar heating of surface waters in pack ice
Perovich et al.,GRL, 2007
Mea
n an
n. h
eat i
nput
, MJ
m–2
.
Solar heat input at75˚N 165˚W
Solar heating linear trend (% yr–1)• Oceans north ofAlaska have receivedat least twice asmuch heat from sunin recent yearscompared to 1980s
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Sea-ice change around Alaska &Impacts on Human Activities
• Introduction• The Arctic sea-ice cover:
Observations & predictions• Alaska sea-ice change• Impacts• Conclusions
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A changing NorthRegime shifts in climate andthe environment that areabout to exceed range ofpast variability and change
Sweeping impacts ofchange on Northernpopulations and cultures
Expansion of globalgeopolitical and economicinterests into the North
Increasing inter-dependence between theArctic region and globalprocesses
BP NorthstarPhoto: BP
Barrow Whaling camp(Photo: Bill Hess) NSIDC
ACIA
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Sea-ice systemservices
• Regulating• Climate regulator• Marine & coastal hazard• Stabilizing element in coastal zone• Geologic agent (ice rafting ofsediments, bottom interaction)
• Provisioning• Transportation corridor• Platform (industry & subsistence)• Freshwater source• Source of food
• Cultural• Subsistence activities• Ice as part of cultural & spirituallandscape (incl. tourism)
• Supporting• Ice-based foodwebs• Reservoir and driver of biologicaldiversity (e.g., extremophiles)
(1) Icescape
(2) Platform &Hazard
(3) Habitat
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Response to changing conditions:Reexamination of EEZ/territorial claimsin the context of marine transportationand resource extraction (Russia, Den-mark/Greenland, Canada)
ACIA, 2004A
rctic
Res
earch
Com
miss
ion,
200
4
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Lease areas in relation to ice conditions
Lease sale data: MMS (2005)
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• Ice circulation patterns help bring old (multiyear) ice toBeaufort Sea coast
• If normal ice drift pattern persists, multiyear ice likely to arriveat Barrow by mid/late spring
Dec 1,2007
Jan 1,2008
FYIMYI
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Annual sea-ice cycle & operational windowsDecember
March
June
September
Melt
Openwater
Stablelandfastice
Freeze-up &ice advance
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Annual sea-ice cycle & operational windowsDecember
March
June
Sep
Melt
Openwater
Stablelandfastice
Freeze-up &ice advance
Spring flooding
Landfast-ice break-outevents
Ice incursions
Early surface meltevents
• Open-wateroperationsregime longer,potential for iceincursions
• Landfast-iceoperationsregime shorter,potential forbreak-outs
• Coastal &offshore iceregime morevariable in time& space
• Highly specific toa given location
Winter-spring icetransition (leaddensities increase)
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The value of integrated sea-ice observations• Remote sensing (km-scale): Ice
extent and evolution• Coastal radar (sub-km scale):
Ice dynamics and evolution• EM thickness and DGPS
topography surveys (sub-kmscale)
• Ice mass-balance site (10s m-scale): sealevel , watertemperature, ice & snowthickness & temperature
• Local ice observations (J.Leavitt, A. Brower Sr. andothers): Iñupiaq expertise & iceuse, annual cycle
• Seasonal Ice Zone ObservingNetwork (SIZONet) IPY Project
M. Druckenmiller et al.
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IPY-1 at Barrow: US Signal Corps Station• Observation Hut (parts in all likelihood still on site)
• Grounded ice off thebeach in August 1883
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0
45
90
1/1 1/31 3/1 3/31 4/30 5/30 6/29 7/29 8/28 9/27 10/27 11/26 12/26
0
12
24Su
n An
gle D
aylight
IPY 1882/83 in context: Melt/Freeze at Barrow (K. Wood, 2004)
2000
1995
1990
1985
1980
1975
1970
188118821883
6/1
9/16
6/13
++++++ ++ + +++ +++++++++ ++
+++++
++
(+)
185218531854
++
(+)
+IPY-1
Maguire (HMS Plover)
IndicatorsFirst BirdsMelt OnsetSnow DisappearsFreeze OnsetLagoons Freeze
+
+
Data sources: US Naval Observatory, Astronomical Applications. NOAA NCDC. R. Stone, NOAA CMDL (Snowmelt). P. Ray, Report of the Point Barrow Exp. R. Maguire, Journal
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Advice & guidance from Iñupiat experts
• Murdoch, John. EthnologicalResults of the Point BarrowExpedition. Washington, D.C.:Smithsonian Institution Press,1988. Reprint. Originallypublished: 1892.
Erk-sing-ra: source of localknowledge recorded by Capt.Maguire at Point Barrow inthe 1850s. “[We] had worseseasons before the Shipcame...” Journal of Rochefort Maguire.Photo: US National Archives.
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Conclusions• Open water season: longer,
potential for ice incursions (icedetection)
• Landfast ice: extent little changed,less stable (lack of groundedridges and stabilizing factors)
• Coastal zone: Change in icedynamics (rafting, sedimententrainment, break-outs)?
• Multi-year ice reservoir remains inCanadian Arctic with overallthinner ice: More variability
• Role of local expertise inresponding and adapting tochanging conditions
Resources:AOOS:
ak.aoos.orgNWS Anchorage Ice Desk:
pafc.arh.noaa.gov/ice.phpNational Snow & Ice Data Center:
nsidc.orgBarrow/Wales Ice Observatory
www.gi.alaska.edu/BRWICEwww.gi.alaska.edu/WLSICE
University of Alaska IPY Initiativeswww.alaska.edu/ipy“North by 2020 - Forum for localand global perspectives on theNorth”
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Case study: Breakout event April 1 & May 28, 2007No. Event Source
1 Few ridges were formed in the landfast ice region off Barrow
due to a lack of a west wind.
Leavitt 2007b
2 There was a lack of multiyear ice incorporated into the
landfast ice. Whaling crews had to haul freshwater to their
camps as opposed to melting multiyear ice.
Brower, H. 2007
3 There was “low-profile” multiyear ice in the landfast ice off
Barrow, as opposed to the “high-profile smooth hills of old
ice” that people are used to seeing.
Brower, A.
2007b
4 There was an “instability” in the landfast ice due to “young
ice forming later in winter.” Also, the pressure ridges were
smaller.
Aiken 2007
5 “Climate change will bring new ice conditions to the
Chukchi [Sea]—young ice will pile up in a new way, even if
thick heavy multiyear ice is not around.”
Brower, H. 2006
www.gi.alaska.edu/BRWICE
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• Spatial andtemporalvariability inkey seasonalevents
• Early onset(e.g. PrudhoeBay) vs. lateonset (e.g.,Point Barrow)
• Stable vs.variable iceregimes
• Importance oflocalconditions
Mahoney et al. (2007)
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Ice morphology
• Potential lackof groundedridges as factorin reduced icestability
• Impact of icemorphology onunder-icecurrents andpotential oildispersal
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Multi-year ice incursions
• Reservoir of MY ice north of Canada: Delay of seasonal iceretreat, summer & winter ice hazard, variability in summer iceconditions over shelf
2006