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Climate Change

Susan Nossal

Department of Physics

University of Wisconsin-Madison

Physics 207 - October 24, 2008

Overview• Greenhouse effect

• Greenhouse gases

• Observations of climate change

• Long term lake ice studies

• Climate change in the upper atmosphere

• Solution strategies

• Conclusions

On a scale of 1-5, how much have human activities contributed to thewarming world that we observe today? 1 (not at all) and 5 (the warming isdue entirely to human activities)

How much has the global average surface temperature risen over the last100 years? A change of 1.0 °C is a change of 1.8 °F

0.1 °C0.75 °C5.0 °C10.0 °C20.0 °C

What are some strategies for reducing emissions of greenhousewarming gases?

about 4

The analogy between the atmosphere and a greenhousehas limitations due to considerations of convection

From Wilson and Buffa From Serway & Faughn

c=fλ

VENUS

www.alderplanetarium.org

Source: IPCC Climate Change 2007: The Physical Science Basis—Summary for Policymakers.

Changes in Heat-trapping Gasesfrom Ice-Core and Modern Data

Source: IPCC Climate Change2007: The Physical ScienceBasis—Summary forPolicymakers.

Since the dawn ofthe industrial era,carbon dioxide andother key heat-trapping gaseshave increased ata rate that is “verylikely to have beenunprecedented inmore than 10,000years.”

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CO2

CH4

N2O

Emissions

Direct Observationsof recent climatechange

From the Intergovernmental Panel on Climate Change, 2007

• extremely unlikelywithout external forcing

• very unlikely due toknown natural causesalone

Observed widespreadwarming

Global ocean

1955 20051980

Annual Trend 1979 to 2005

Surface Troposphere

IPCC presentation, 2007

From the United States Geological Survey

Signs of climate change• 11 of the last 12 years (1995-2006) areamong the 12 warmest years on record

• Mountain glaciers and snow cover havedeclined on average in both hemispheres

• Global average sea level rise

• Increasing Arctic temperatures

• Shrinking of Arctic sea ice

• More intense and longer droughts

• Increased frequency of heavy precipitationevents

• More extreme temperature events

Lake Mendota Long Term Ice Cover Studies

Photo and data from Prof. John Magnuson,UW Dept. of Limnology

January 20, 2007Feb 1

Jan 15

Jan 1

Dec 1

Dec 15

1855 1875 1895 1915 1935 1955 1975 1995

1855 1900 1950 2000

1856 - 1977

1978 - 2005

1995 - 2005

Balsiger 2007

0

30

60

90

120

150

180

1850 1875 1900 1925 1950 1975 2000

Du

rati

on

of

Ice C

over (

Days)

Duration

Linear Model

Best ARMA Model

Mon

ths

of I

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over

1850 1900 1950 2000

5

4

3

2

1

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Long-Term Changes in Ice Cover Duration

Lake Mendota, Wisconsin

1850 1900 1950 2000

Jan 1

Dec 1

Feb 1

Mar 1

Apr 1

May 1

Freeze

Breakup

Lake / BayChequamegon Bay

ShellMendotaMonona

RockGeneva

Magnuson 2004

Changes in Ice Around Wisconsin

Historical Trendsin Lake and RiverIce-On & Ice-OffDatesaround theNorthernHemisphere

(37 of the 39 time seriesare in the directionof warming)

Source: IPCC 3rd Assessment 2001 Modified from Magnuson et al. 2000

1840 1880 1920 1960 2000

Nov 1

Dec 1

Jan 1

Feb 1

Mar 1

Apr 1

May 1

Ice

On

Ice

Off

MacKenzie River NW Terr.

Kallavesi, Finland

Lake Mendota, WI

Lake Mendota, WI

Grand Traverse Bay, Lake Michigan

Baikal, Russia

Grand Traverse Bay, Lake Michigan

Kallavesi, Finland

Baikal, Russia

Potential Impacts in the Great Lakes Region• Higher average temperatures in both winter and summer

• Increased frequency of days with extreme heat

• Increased frequency of heavy rain storms

• Possible increase in the length of growing season, but decreased soilmoisture

• Increased health risks related to extreme heat

• Increased formation of ground-level ozone, likely exacerbating asthmaand other respiratory diseases

• Changes in species’ populations such as trout, spruce, fir, and birds

www.ssec.wisc.edu

Regions of the Earth’s Atmosphere

Courtesy of Windows to the Universe, http://www.windows.ucar.edu

Predictions for Climate Change in theUpper Atmosphere

• Temperatures are expected to cool

• Densities of most constituents areexpected to decrease

• Changes in concentrations of manyspecies

Coupling of hydrogen-containing species

1Courtesy of Windows to the Universe, http://www.windows.ucar.edu2from: http://earthobservatory.nasa.gov/Features/BiomassBurning/3© Pekka Parviainen From http://lasp.colorado.edu/noctilucent_clouds/4Source: Carruthers, Page, and Meier, Apollo 16 Lyman alpha imagery of the hydrogen geocorona, J. Geophys. Res., 81, 1664, 1976. and .pluto.space.swri.edu/.../ apollo_geocorona2.gif

Sources of methane include:Wetlands, termites, agriculture,industry, mining, biomass burning

CH4, H2O, H2 chemistry &photolysis reactions

1

3

14

Atomic hydrogen becomesincreasingly dominant with altitude

2

Instrumentation• Optical instruments are used to study light emitted or absorbed by atomsand molecules in the atmosphere.

• Chemical tests, RADAR and LIDAR instruments are others used toinvestigate the atmosphere.

• Long term climate observations require instrument stability, reproducibleobserving conditions, as well as careful characterization and calibration ofthe instrument.

• Understanding sources of uncertainty is critical to interpreting the data.

Wisconsin Hα Mapper Fabry-Perot from [Haffner et al., 2003]

1http://www.fabryperot.com/images/fixed_ets.jpg

• Solar Cycle 23 winter, low galactic emission region WHαM (Kitt Peak, AZ)thermospheric+exospheric Hα column emission intensities.

• From 23 nights of observations.

[Nossal et al., 2008]

Solar Cycle 23 WHAM Observations

Attribution• are observed

changesconsistent with

expectedresponses toforcings

inconsistentwith alternativeexplanations

Observations

All forcing

Solar+volcanic

Reduction of heat-trapping emissions• If global temperatures rise more than 2ºC above pre-industrial levels, therisk of severe impacts of climate change increases

• A 2-3ºC of warming could threaten 20-30% of the Earth’s species withextinction

• Other potential impacts include widespread melting of the Greenlandand West Antarctica ice sheets, sea level rise and coastal flooding,increased number of days of severe temperatures, expansion of drought-prone regions and water scarcity.

• A minimum reduction in the United States’ CO2 equivalent emissions ofat least 80% below 2000 levels by 2050. This projection assumes that theemissions by industrial nations peak in 2010, before starting to decline.

Sources of U.S. Energy Related CO2 Emissions: 2004

Transportation

33.1%

Industrial

15.4%Residential

6.6%

Commercial

4.0%

Other Electricity

Generation

7.0%

Electricity Generation

from Coal

33.8%

Source: EPA 2006

Some of the Many Solution Strategies• Moratorium on building of more coal-fired power plants

• Development, implementation and use of renewable energy

• Further development and use of public transportation systems

• Requirements for greater energy efficiency standards for vehicles

• Reduction of car and airplane trips

• Use of energy efficient appliances

• Eating locally produced foods

• Use of energy efficient lighting

• Energy efficient construction

• Economy based on more local production

• Forest preservation and reforestation

• Carbon tax

www.ci.madison.wi.us/metro

www.madfarmmkt.org

www.ucsusa.org

Conclusions from the IPCC 4th Assessment• “Warming of the climate system is unequivocal, as is now evident fromobservations of increases in global average air and ocean temperatures,widespread melting of snow and ice, and rising global average sea level.”

• “The current atmospheric concentration of carbon dioxide and methane“exceeds by far the natural range over the last 650,000 years.”

• “Most of the observed increase in globally averaged temperatures sincethe mid-20th century is very likely due to the observed increase inanthropogenic greenhouse gas concentrations.”

• “Even if the concentrations of all greenhouse gases and aerosols hadbeen kept constant at 2000 levels, a further warming of about 0.1 °C perdecade would be expected” for the next two decades.

• “Continued greenhouse gas emissions at or above current rates wouldcause further warming and induce many changes in the global climatesystem during the 21st century that would very likely be larger than thoseobserved during the 20th century.”

Conclusions• Knowledge of both natural and human influences is needed tounderstand the climate system and processes of change.

• Geographic and altitude studies are needed for a whole atmosphereunderstanding of base properties, natural variability and climate change.

•Temperatures, densities, composition, and weather patterns throughoutthe atmosphere are predicted to change in response to increasingconcentrations of greenhouse gases such as CO2 and CH4 with warmingtemperatures at lower altitudes and cooling temperatures at higheraltitudes.

• Deep reductions in greenhouse gas emissions are required to avert themost severe impacts of climate change.

• There are many, varied opportunities for reducing greenhouse gasemissions at international, national, local, and personal levels.

Intergovernmental Panel on Climate Change: www.ipcc.ch

References:Intergovernmental Panel on Climate Change: www.ipcc.ch

Union of Concerned Scientists: www.ucsusa.org

UW Conservation Project: www.conserve.wisc.edu

Indigenous Environmental Network: www.ienearth.org