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
ce C
over
1850 1900 1950 2000
5
4
3
2
1
0
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