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SOAR 2007

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

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SOAR 2007

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  1. SOAR 2007 Current Changes and Future Climates

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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 Why isn't it working yet?

  7. 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

  8. 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

  9. 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 socio-economic 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

  10. 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

  11. 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

  12. 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”

  13. IPCC • 4th Assessment • Released 2007 • WGI = 701 pages! • available on line ipcc-wg1.ucar.edu/wg1 • available in print Cambridge U. Press

  14. IPCC • 4th Assessment • Released 2007 • WGI = 701 pages! • available on line ipcc-wg1.ucar.edu/wg1 • available in print Cambridge U. Press

  15. 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

  16. 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

  17. Union of Concerned Scientitsts • Confronting Climate Change in the U.S. Northeast: Science, Impacts and Solutions http://www.ucsusa.org/global_warming/

  18. 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” Altitude Temperature RF = net flux imbalance at tropopause

  19. Atmospheric Structure RF = net flux imbalance at tropopause • Layers (from surface) • Troposphere – sphere of weather • Stratosphere – sphere of ozone (O3) • Mesosphere • Ionosphere – sphere of ions

  20. IPCC ARF WGI • Components of Climate Change Accounts for natural processes eg. Changes in evaporation eg. Melting permafrost releasing methane

  21. IPCC ARF WGI • Radiative Forcing 1750 - 2005 “Ozone Layer” absorbs UV, reduces RF at tropopause Carbon Dioxide Methane 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)

  22. IPCC Climate Drivers • Greenhouse Gases: CO2, CH4, H2O, NOx Grey Bars = Natural Variability Com-bined rate of change

  23. IPCC Climate Drivers • Greenhouse Gases: CO2, CH4, H2O, NOx Grey Bars = Natural Variability Com-bined rate of change

  24. IPCC Changes Since 1850 • Global Average Temperature • Global Average Sea Level • mostly thermal expansion • Northern Hemisphere Snow Cover

  25. UCC Northeast US • Climate of New York State

  26. UCC Northeast US 100-yr Flood becoming 10-yr Flood

  27. UCC Northeast US • Snow cover decreasing Com-bined rate of change

  28. IPCC ARF • Continued Warming What we’re committed to by past behavior!

  29. IPCC ARF • Effects of Changing Mean Does not mean it never gets cold!

  30. IPCC ARF • Location of Changes Uncertainties

  31. IPCC ARF • Location of Changes

  32. 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!

  33. The Skeptics • Journal of American Physicians & Surgeons 2007 • Mailed to all SLU Physics Professors Tuesday!!

  34. The Skeptics • Claims all warming due to solar activity Scale minimizes hydrocarbon use, leaves out first century.

  35. The Skeptics • Claims all warming due to solar activity Scale minimizes hydrocarbon use, leaves out first century.

  36. What to Do? • Complex system hard to model • Experts don’t agree • Could be global disaster Ignore it? Adapt? Mitigate it? Kyoto + ?

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