Climate ChangeSusan NossalDepartment of PhysicsUniversity of Wisconsin-MadisonPhysics 207 - October 24, 2008Overview• Greenhouse effect• Greenhouse gases• Observations of climate change• Long term lake ice studies• Climate change in the upper atmosphere• Solution strategies• ConclusionsOn 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 °F0.1 °C0.75 °C5.0 °C10.0 °C20.0 °CWhat are some strategies for reducing emissions of greenhousewarming gases?about 4The analogy between the atmosphere and a greenhousehas limitations due to considerations of convectionFrom Wilson and Buffa From Serway & Faughnc=fλVENUSwww.alderplanetarium.orgSource: IPCC Climate Change 2007: The Physical Science Basis—Summary for Policymakers.Changes in Heat-trapping Gasesfrom Ice-Core and Modern DataSource: 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.”www.pca.state.mn.us/cleanup/landfills.htmlwww.epa.gov/nitrousoxide/sources.htmlCO2CH4N2OEmissionsDirect Observationsof recent climatechangeFrom the Intergovernmental Panel on Climate Change, 2007• extremely unlikelywithout external forcing• very unlikely due toknown natural causesaloneObserved widespreadwarmingGlobal ocean195520051980Annual Trend 1979 to 2005Surface TroposphereIPCC presentation, 2007From the United States Geological SurveySigns 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 eventsLake Mendota Long Term Ice Cover StudiesPhoto and data from Prof. John Magnuson,UW Dept. of LimnologyJanuary 20, 2007Feb 1Jan 15Jan 1Dec 1Dec 151855 1875 1895 1915 1935 1955 1975 19951855 1900 1950 20001856 - 19771978 - 20051995 - 2005Balsiger 200703060901201501801850 1875 1900 1925 1950 1975 2000Duration of Ice Cover (Days)DurationLinear ModelBest ARMA ModelMonths of Ice Cover1850 1900 1950 2000543210Long-Term Changes in Ice Cover DurationLake Mendota, Wisconsin1850 1900 1950 2000Jan 1Dec 1Feb 1Mar 1Apr 1May 1FreezeBreakupLake / BayChequamegon BayShellMendotaMononaRockGenevaMagnuson 2004Changes in Ice Around WisconsinHistorical 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. 20001840 1880 1920 1960 2000Nov 1Dec 1Jan 1Feb 1Mar 1Apr 1May 1Ice OnIce OffMacKenzie River NW Terr.Kallavesi, FinlandLake Mendota, WILake Mendota, WIGrand Traverse Bay, Lake MichiganBaikal, RussiaGrand Traverse Bay, Lake MichiganKallavesi, FinlandBaikal, RussiaPotential 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 birdswww.ssec.wisc.eduRegions of the Earth’s AtmosphereCourtesy of Windows to the Universe, http://www.windows.ucar.eduPredictions for Climate Change in theUpper Atmosphere• Temperatures are expected to cool• Densities of most constituents areexpected to decrease• Changes in concentrations of manyspeciesCoupling of hydrogen-containing species1Courtesy 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.gifSources of methane include:Wetlands, termites, agriculture,industry, mining, biomass burningCH4, H2O, H2 chemistry &photolysis reactions1314Atomic hydrogen becomesincreasingly dominant with altitude2Instrumentation• 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 ObservationsAttribution• are observedchangesconsistent withexpectedresponses toforcingsinconsistentwith alternativeexplanationsObservationsAll forcingSolar+volcanicReduction 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
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