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EPSS 15: Introduction to Oceanography �Lecture 18: Climate Change

University of Colorado, http://nsidc.org/

Acknowledgements:Jon Aurnou, UCLA“Meteorology Today”,�

Chapters 18 & 19, C. Donald Ahrens, Todd

Albert, CIRES, University of Colorado

For more information, visit:www.noaa.gov (Nat’l. Oceanic & Atmos.

Admin.)www.nasa.gov (Nat’l. Aeronautics & Space

Admin.)www.realclimate.org(Climate Scientists’ ‘blog)

Announcements

Figure by Janaki/photo source unknown/ICANHASCHEEZBURGER.COM, �http://icanhascheezburger.com/2007/11/20/i-has-a-icecap-noo-they-be-stealin-my-icecap/

Lab Finals this Week in 3820 Geology

Lecture Final Thur., June 15, 8:00a-11:00a

Moore 100 Extra Credit Video

Thursday, 4:00-5:00p, Moore 100

Lecture Final Review Session Friday, 3:00-4:30pm,

Moore 100 Course Evaluations

until Friday! Extra Credits due Friday!

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Aquaculture…

Figure from UN Food and Agriculture Organization World Review of Fisheries and Agriculture 2014, �http://www.fao.org/3/a-i3720e.pdf

Accounts for 40% of world harvest for human consumption as of 2012: �

our oceans, rivers and lakes are being domesticated!

MaricultureThe growth segment �

of modern fisheries.Very important where�

wild fisheries have�already collapsed �(e.g., Bangladesh)

Shrimp farming in�particular may�occur at expense �of mangrove �swamps & other�sensitive areas

Growth of shrimp farming, Honduras, 1987-1999. Image by Jesse Allen, NASA Earth Observatory, Public Domain, http://earthobservatory.nasa.gov/

IOTD/view.php?id=6339

1987

1999

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SalmonAlmost all fish sold as “Atlantic” or “Norwegian” Salmon is farm raised -- and fed

synthetic astaxanthin pigment (a chemical cousin of vitamin A found naturally in some zooplankton) to look like wild salmon.�

�The same pigment may be fed to chickens to make egg yolks orange.

Photos of wild (left) and farmed (right) by Neeta Lind, Flickr, Creative Commons A 2.0, �http://www.flickr.com/photos/neeta_lind/sets/72157601103903581/

Salmon Mariculture•  Mostly Atlantic salmon species, farmed in pens in wave-protected

coves, but inevitably porous to the environment

�Feed includes fish meal/ fish oil, ~ 2.5 kg / 1 kg Salmon

•  Salmon farming still requires ocean extraction of feed•  Development of vegetarian feed ongoing

High population density and genetic uniformity can foster disease and parasites

Farmed salmon escape pens..Spread disease , breed with wild populations?

One solution: inland tank farms

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Fish market, Chijin District, Kaohsiung City, Taiwan. Photo by Changlc, Wikimedia Commons, Public Domain, http://commons.wikimedia.org/wiki/File:Seafood_chijin.jpg

Questions

Global Climate ChangeMovie of minimum N. Pole sea ice extent from 1979 � 2016.�Sept. 16, 2012 – Lowest area ever recorded (3 million km2).

www.nasa.gov

Movie by Starr et al., NASA, Public Domain, https://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=4573

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Inset from https://nsidc.org/data/seaice_index/images/daily_images/N_daily_extent_hires.png �OK for educational use

Graph generated with NSIDC interactive charting �

http://nsidc.org/arcticseaicenews/

charctic-interactive-sea-

ice-graph/

Definition of “Climate”•  Climate:The accumulation of daily and

seasonal weather events over a long period of time

–  Microclimate: the cool shady spot under a big elm tree

–  Mesoclimate: the conditions in a region a few square kilometers in size, i.e. the Los Angeles Basin

–  Macroclimate: Climate of an area the size of a country, continent, or ocean.

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Definition of “Climate”Climate:The accumulation of daily and seasonal weather

events over a long period of timeGlobal Climate: Climate extending over the entire Earth.

NASA image, Public Domain, �http://airsteam.jpl.nasa.gov/multimedia/image_releases_2003/april_avgbrtnstmp_2003/

Questions about changing climate•  Why is the climate changing?

–  Is this temporary and/or cyclical?–  Is it caused by human activity?–  What’s going to happen in the future?

•  As scientists we want to build a predictive model of future climate.

•  What’s the first thing to do?

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Understanding Past Climates•  Past century or so: thermometer records

–  care needed to track calibration, drift, global sampling•  For climate before ~1900 this is difficult

–  Methods that work in one area (ice caps) may not work elsewhere (tropical ocean).

–  High resolution records (tree rings) don’t often extend back very far.

•  Requires multidisciplinary approaches•  Timescales of interest and locations both important •  All methods depend on “proxies” for temperature

–  Impossible to directly measure past temperatures except for very recent past in areas with people (w/ thermometers!).

Paleo-climate EvidenceGeologic features

Ancient clues in old continental rocks

Landforms show effects of past glacial activity

Ocean Sediment Cores~200 Million Year Record

Deep Ice CoresContain info going back

~800,000 yearsOthers: Coral cores, lake

sediment cores (pollens), tree rings, etc…

Yosemite Valley, by snty-tact, Creative Commons A S-A 3.0. �http://commons.wikimedia.org/wiki/File:Yosemite_Valley.JPG

National Ice Core Lab storage freezer, by Eric Cravens, Public Domain, http://commons.wikimedia.org/wiki/File:NICL_Freezer.jpg

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Paleoclimate: Oceanic ProxiesForaminifera CaCO3 shells are used to study

past sea surface temperatureMost O atoms have 8 p + 8 n = 16O•  1/500 oxygen atoms has 2 extra

neutrons–  18O isotope

•  H218O evaporates slightly less

easily than H216O

•  Ice caps form from snow - precipitated from water vapor -and are 18O-poor.

•  Remaining ocean water becomes 18O-rich

** 18O concentration of ancient seawater is preserved in CaCO3 shells

Micrograph by Hannes Grobe, Alfred Wegener Institut, Creative Commons A 3.0 Unported,

http://commons.wikimedia.org/wiki/File:Neogloboquadrina-pachyderma_hg.jpg

Foraminifera: Neogloboquadrina pachyderma

H218O evaporates slightly less easily than H2

16O.�Ice caps have little H2

18O, the leftover water in the ocean has extra H218O �

Illustration: Robert Simmon, NASA GSFC, Public Domain, http://earthobservatory.nasa.gov/Features/Paleoclimatology_OxygenBalance/oxygen_balance.php

Graph: Jouzel, J., R. D. Koster, R. J. Suozzo, G. L. Russell. 1994. Stable water isotope behavior during the last glacial maximum: A general circulation model analysis. Journal of Geophysical Research, 99: 25791-25802.

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Paleoclimate Oceanic Measurements

Foraminifer shells up to one million years old from ocean sediment cores show clear 100,000 year cycles during “ice ages”

–  Glacial Periods ~ 90,000 years long–  We are presently in an interglacial period–  The last glacial maximum (LGM) was 18,000 ya

18O-poor ocean

18O-rich ocean

Figure by Dragon’s Flight/Jo, Wikimedia Commons, Creative Commons A Noncommercial S-A 2.5, http://commons.wikimedia.org/wiki/File:Five_Myr_Climate_Change.svg

“Recent” Climate MeasurementsThis curve is put together from different types of PROXY from many different LOCATIONS on the planet. It is constantly being refined and extended back in time.

Figure from 2001 Intergovernmental Panel on Climate Change, 3rd Assessment Report, Public Domain, http://www.grida.no/climate/ipcc_tar/wg1/pdf/WG1_TAR-FRONT.PDF�

Data assembly and analysis from Mann et al. (1998) Nature v. 392, p. 779-787.

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Recent Climate MeasurementsPrevious slide (also at right):

Blue line: corals, tree ring, ice core data

Red line: thermometer dataBlack line: smoothed dataGrey: uncertainty

Left: hockey stick, photo from ProHockeyEquipment.com; top right: same as previous slide; bottom right: figure by Hanno, based on Jones & Mann (2004) and Jones et al. (2005), Public Domain, http://commons.wikimedia.org/wiki/

File:Global_temperature_1ka.png

T (ºC)

Year (AD)

Present State of the Climate•  About 1 ºC global �

average temperature �increase over �the last 100 years.

•  Largest increase �in the last 1000 yrs

•  Global temperatures �haven’t varied by �more than 2ºC in the �last 10,000 years �

�So 1º is a large shift on the timescale of civilization

•  20th-21st century temperature variation difficult to explain with natural climate variability.

–  Very likely most of the temperature increase is due to human activity (anthropogenic climate change).

Graph & data from NASA Goddard Institute for Space Studies, Public Domain. http://data.giss.nasa.gov/gistemp/graphs_v3/

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Why is the Climate Warming?•  Most likely cause: enhanced

atomospheric greenhouse effects.•  GREENHOUSE EFFECT?

Sun

A greenhouse stays warm because it is transparent to incoming sunlight.

But glass traps infrared (heat) radiation, preventing the energy absorbed from the sun from escaping.

Photo by National Rural Knowledge Exchange, Flickr, Creative Commons A 2.0, http://www.flickr.com/photos/8228133@N04/1091783222

Greenhouse EarthOur atmosphere acts like a greenhouse!Instead of glass or plastic, heat radiation is absorbed and scattered by gasses like CO2 and H2O-vapor

Frédéric Bellaiche/NASA, GNU PL/Public Domain, �http://commons.wikimedia.org/wiki/File:Jar.svg & �

http://commons.wikimedia.org/wiki/File:Earth_Western_Hemisphere_white_background.jp

g

H2OCO2Animations by E. Schauble, UCLA, http://www2.ess.ucla.edu/~schauble/molecular_vibrations.htm

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The atmospheric greenhouseShort wavelengths of light from

the hot surface of the sun �(5525 K = 5252ºC !) can get

through the Earth’s atmosphere, but long wavelengths of light from the Earth’s lukewarm

surface �(210-310 K = –63ºC - +37ºC)

can’t easily escape.

Figure by Robert A. Rohde, Global Warming Art Project, Creative Commons A Noncommercial S-A 2.5, http://commons.wikimedia.org/wiki/

File:Atmospheric_Transmission.png

Animations by E. Schauble, UCLA, http://www2.ess.ucla.edu/~schauble/

molecular_vibrations.htm

Too much … �becomes a �problem.

Greenhouse Increase•  A little greenhouse is good!

Without any CO2 or H2O to prevent heat from escaping, Earth would have an average temperature around �–20ºC. Brrrr.

Dr. Pieter Tans, NOAA/ESRL, Public Domain, (www.esrl.noaa.gov/gmd/ccgg/trends)

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Paleoclimate Quantification MethodsDEEP Ice Cores taken

primarily in Greenland and Antartica

Ice also preserves a 18O record, and traps ancient gas in bubbles within ice as well as dust, particulates, acidity, other chemical tracers

This is a high resolution record, with each year containing a distinct layer of ice---like tree rings West Antarctica ice core, photo by Chad

Naughton, US National Science Foundation, Public Domain, http://photolibrary.usap.gov/

AntarcticaLibrary/WAISICECORE2.JPG

Greenhouse Gases vs. Climate

NOAA/IPCC figure, Public Domain, http://www.ncdc.noaa.gov/paleo/pubs/ipcc2007/fig63.html

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Greenhouse Gases vs. Climate

NOAA figure, data from Jouzel et al. 2007; Lüthi et al. 2008; Public Domain, �https://www.ncdc.noaa.gov/global-warming/temperature-change

Main source of increasing CO2 concentration in the atmosphere can be tied to burning of organic carbon (fossil fuels and biomass) because these sources are 13C-poor.

Volcanic CO2 (and concrete by-products) are 13C-rich.

CO2 recently began to rise steeply…

Plots by Robert Rohde, Global Warming Art Project, CC A Noncommercial S-A 2.5, http://www.globalwarmingart.com/wiki/File:Carbon_History_and_Flux_Rev_png

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Volcanic CO2, also concrete manufacture

Oil, coal, gas, plants&wood

More 13C

Less 13C

CO2 would rise much faster if the ocean didn’t dissolve a lot of it!

Dr. Pieter Tans, NOAA/ESRL, Public Domain, (www.esrl.noaa.gov/gmd/ccgg/trends)

Scripps CO2 Program, http://scrippsco2.ucsd.edu/graphics_gallery/isotopic_data/mauna_loa_and_south_pole_isotopic_c13_ratio

CO2-enhanced greenhouse•  CO2 warms the atmosphere.•  By itself, increased CO2 only modestly

increases average temperatures.

•  Then how can it trigger global warming?

?

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Climate Change & Feedback Mechanisms

•  Positive Feedback: Amplifies a change in the system

•  Negative Feedback: Tends to return a system back towards its initial state

Positive Feedback Mechanisms•  Atmospheric CO2 heats atmosphere

which leads to enhanced evaporation…�

•  Water Vapor Greenhouse Effect:–  Warming temperatures cause more

seawater to evaporate –  Further warms atmosphere–  Leads to further evaporation…

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Positive Feedback Mechanisms•  Snow-Albedo Feedback:

–  Warming temperatures cause more snow and ice to melt at poles

–  Less reflective materials absorb more solar heating

–  This further heats up the climate system–  This leads to further melting of snow and

ice…

Negative Feedback Mechanisms•  Radiative Feedback:

–  Warmer materials radiate away their heat more effectively

–  The warmer the Earth becomes, the more strongly it radiates heat back to space

–  This tends to stabilize the system against warming up.

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Other Feedback Mechanisms•  Cloud Effects:

–  As a warmer Earth generates a more humid atmosphere more clouds will form

–  Some types of clouds (low thick clouds especially -- i.e. rainclouds) act to effectively reflect away some solar energy–  Negative Feedback

–  Others (high, wispy, cold clouds) keep heat in.–  Positive Feedback

Putting the feedbacks & forcings together

Climate models try to include the best estimates of the effects of CO2, other forcings (like sulfate, which forms tiny aerosol droplets that reflect sunlight), and feedbacks like H2O vapor increases and clouds.

These models do a *good job* of reproducing known changes in temperature over the last 100 years.

The forcing & feedback parameters are NOT fitted to the 20th century temperature data to make this agreement look better!

Plots by Robert Rohde based on the DOE PCM model, from Meehl et al. (2004) Global Warming Art Project, Creative Commons A Noncommercial S-A 2.5, �http://commons.wikimedia.org/wiki/File:Climate_Change_Attribution.png

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Plots by Robert Rohde Global Warming Art Project, Creative Commons A Noncommercial S-A 2.5, �http://commons.wikimedia.org/wiki/File:Global_Warming_Predictions.png

These models assume fairly strong growth in greenhouse gas emissions over the next century (scenario A2). Recent fossil-fuel burning and CO2 increases appear to be even stronger than this

scenario assumes…

Future Projections, Uncertainties•  Climate models predict global

temperature increases between 1.1ºC and 6.4ºC over the next century �(depending on the model, and on future CO2 emissions)

•  Probably will be the greatest warming event in the last 10,000 years

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Roles of the Ocean in Future Climate•  How much CO2 will the ocean absorb?•  Will increased temperatures enhance or

decrease phytoplankton activity, which will act as either a source or sink for CO2?

•  Warmer water dissolves less gas. Will a warmer ocean release dissolved CO2?

•  How strongly will the deep circulation respond to and effect variations in global climate?

Possible Consequences•  Northern Hemisphere sea ice decrease

by > 20% over past 25 years•  May disappear completely during

summer by 2030

NASA images, Public Domain, http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=3464

Minimum Sea Ice, 1979 Minimum Sea Ice, 2007

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Effect on the ocean: sea level rise

Change is mostly caused by melting ice on land and warming of the ocean (thermal expansion).

Data, plot by Church and White (2011 – updated 2013), CSIRO, http://www.cmar.csiro.au/sealevel/sl_data_cmar.html

Future sea level rise

Figure from IPCC #5 assessment, Working Group 1, Chapter 5

Projected rise of ~30–100 cm in the next 85

years.

Destabilization of ice sheets in Greenland and West Antarctica (which are both likely) could

lead to several meters of sea level rise in the

future.

Purple future: greenhouse gas emissions peak by 2020, then decline.

Orange future: greenhouse gas emissions continue to rise through 21st century. à THIS IS US SO FAR!

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The global response…Kyoto Treaty -- went into effect Feb. 16, 2005.�

Participating developed �countries pledged not to �increase CO2 emissions.

Paris agreement ��adopted Dec. 12, 2015.�Aimed at keeping warming �to 2ºC or less.�

�

However, holding down CO2 emissions will also tend to reduce air & water pollution, may help avoid fossil fuel shortages…

Clearly relevant in the LA Basin

Figure by Emturan/updated May 2011 by Elekhh, Wikimedia Commons, Creative Commoms A S-A 3.0, http://en.wikipedia.org/wiki/File:Kyoto_Protocol_participation_map_2010.png

Thanks for coming!

Figure by Erich C. Treeby/DailyMail.co.uk/ICANHASCHEEZBURGER.COM, �http://icanhascheezburger.com/2009/01/13/funny-pictures-eliminate-ur-carbon-footprint/