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SOAR 2007 Current Changes and Future Climates Predicting the Future Climate Systems Atmosphere – changes over hours Oceans – surface changes over weeks – depths change over millennia Biosphere – changes annually to centuries Cryosphere – ice, glaciers permafrost, snow – various change scales Geosphere – volcanos, continental drif – long time scales, large changes Modeling the Climate Systems & Feedbacks Among Radiation insolation (incoming sunlight varies) reflection, absorption, re-radiation by surface, air Water cycle evaporation, precipitation, runoff Land surface soil moisture, vegitation, topography, snow & ice Ocean surface currents, deep currents, chemistry (salinity) Sea Ice strongly affected by feedbacks Feedbacks Positive Any change leads to further change eg. Ball on a hill Negative System always returns to equilibrium eg. Ball in a bowl Neutral System stays in new state eg. Ball on a plain Feedbacks Greenhouse Effect: Warming Good … makes Earth inhabitable!! Ground absorbs sunlight Ground heats (parking lots in summer) Ground radiates heat (Infrared, IR) Atmosphere absorbs (some) IR Atmosphere heats Feedbaack Mechanisms Evaporation Plant growth Ice-Albedo effect Feedbacks Feedback Mechanism: Evaporation H2O vapor absorbs more IR warming increases? Clouds shade surface, cool it, warming stops? warming decreases? Feedback Mechanism: Plant Growth More CO2 increases plant growth More plant growth is good!! Plants absorb CO2 (Keeling curve annual cycles CO2 is Reduced Feedbacks Feedback Mechanism: Ice Albedo Effect Warming melts glaciers, sea ice Ground warms more than snow/ice Ground warms, radiates more IR Atmosphere warms More ice melts warming increases Cooling increasing glaciers More sunlight reflected Ground Cools cooling increases Feedbacks Feedback Mechanism: Ice Albedo Effect Warming melts glaciers, sea ice Ground warms more than snow/ice Ground warms, radiates more IR Atmosphere warms More ice melts warming increases Cooling increasing glaciers More sunlight reflected Ground Cools cooling increases IPCC Intergovernmental Panel on Climate Change Established in 1988 World Meteorological Org. (WMO) UN Environment Programme (UNEP) Mandate “The role of the IPCC is to assess on a comprehensive, objective, open and transparent basis the scientific, technical and socioeconomic information relevant to understanding the scientific basis of risk of human-induced climate change, its potential impacts and options for adaptation and mitigation.” http://www.ipcc.ch/about/about.htm IPCC Intergovernmental Panel on Climate Change “The IPCC does not carry out research nor does it monitor climate related data or other relevant parameters. It bases its assessment mainly on peer reviewed and published scientific/technical literature. Its role, organisation, participation and general procedures are laid down in the ‘Principles Governing IPCC Work’“ http://www.ipcc.ch/about/about.htm IPCC Working Groups I: Science knowns, unknowns & projections II: Impact and Adaption vulnerability: natural and human consequences: + and – III: Mitigation options for changing human behavior and impact Task Force on National Greenhouse Gas Inventories IPCC Intergovenmental Panel on Climate Change View of the bulk of the scientific community Computer models estimate feedbacks Reports every 5 years 2007 report available in print & electronic 3rd Assessment report gave “Hockey Stick” IPCC 4th Assessment Released 2007 WGI = 701 pages! available on line ipcc-wg1.ucar.edu/wg1 available in print Cambridge U. Press IPCC 4th Assessment Released 2007 WGI = 701 pages! available on line ipcc-wg1.ucar.edu/wg1 available in print Cambridge U. Press Assessment Report Four (ARF) Findings of Working Group I Summary for Policymakers (18 pages) Human & Natural Drivers of Climate Change Direct Observations of Recent Climate Change A Paleoclimatic Perspective Understanding and Attributing Climate Change Projections of Future Changes in Climate Assessment Report Four (ARF) Findings of Working Group I Technical Summary (66 pages) Chamges in Human & Natural Drivers of Climate Observations of Changes in Climate Understanding and Attributing Climate Change Projections of Future Changes in Climate Robust Findings and Key Uncertainties Union of Concerned Scientitsts Confronting Climate Change in the U.S. Northeast: Science, Impacts and Solutions http://www.ucsusa.org/global_warming/ IPCC ARF WGI Radiative Forcing “The change in net (down minus up) irradiance (solar plus longwave; in W/m2) at the tropopause after allowing for stratospheric temperatures to readjust to radiative equilibrium, but with surface and tropospheric temperatures and state held fixed at the unperturbed values” RF = net flux imbalance at tropopause Atmospheric Structure Layers (from surface) Troposphere – sphere of weather Stratosphere – sphere of ozone (O3) Mesosphere Ionosphere – sphere of ions RF = net flux imbalance at tropopause IPCC ARF WGI Components of Climate Change Accounts for natural processes eg. Changes in evaporation eg. Melting permafrost releasing methane IPCC ARF WGI Radiative Forcing 1750 - 2005 Carbon Dioxide Methane “Ozone Layer” absorbs UV, reduces RF at tropopause Buildings increase surface albedo relative to forests Aerosols (particles) reflect sunlight AND increase cloud cover (eg. Contrails) Solar radiation has increased since 1750 (Little Ice Age end) IPCC Climate Drivers Greenhouse Gases: CO2, CH4, H2O, NOx Grey Bars = Natural Variability Combined rate of change IPCC Climate Drivers Greenhouse Gases: CO2, CH4, H2O, NOx Grey Bars = Natural Variability Combined rate of change IPCC Changes Since 1850 Global Average Temperature Global Average Sea Level mostly thermal expansion Northern Hemisphere Snow Cover UCC Northeast US Climate of New York State UCC Northeast US 100-yr Flood becoming 10-yr Flood UCC Northeast US Snow cover decreasing Combined rate of change IPCC ARF Continued Warming What we’re committed to by past behavior! IPCC ARF Effects of Changing Mean Does not mean it never gets cold! IPCC ARF Location of Changes Uncertainties IPCC ARF Location of Changes The Skeptics Important voices! Skeptics keep science honest Agreements CO2 in atmosphere is increasing CO2 levels correlate with temperature Arguments Climate is driven exclusively by insolation Milankovitch Cycles Sunspot Cycles Too expensive to reduce CO2: Adapt Global warming is good! The Skeptics Journal of American Physicians & Surgeons 2007 Mailed to all SLU Physics Professors Tuesday!! The Skeptics Claims all warming due to solar activity Scale minimizes hydrocarbon use, leaves out first century. The Skeptics Claims all warming due to solar activity Scale minimizes hydrocarbon use, leaves out first century. What to Do? Complex system hard to model Experts don’t agree Could be global disaster Ignore it? Adapt? Mitigate it? Kyoto + ?