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Feb. 17, 1993 Climate Change Feb. 21, 2000 Photo of glacial retreat on Mount Kilimanjaro (Feb. 1993 to Feb. 2000) from Wikipedia; Map of Africa from www.admin.uio.no Weather Patterns are Dynamic e.g., monthly variation Temperature Image from Wikipedia (see “Climate”) Weather Patterns are Dynamic e.g., monthly variation Precipitation Image from Wikipedia (see “Climate”) Earth’s Climate is also Dynamic Climate Change (or Variation) Characterizes Earth’s History Climate Change – a shift of average weather across a region Image from Wikipedia (see “Geologic temperature record”) Earth’s Climate is also Dynamic Climate Change (or Variation) Characterizes Earth’s History E.g., Eocene temperature was 4 – 6 °C warmer than today Image from Wikipedia (see “Geologic temperature record”) Earth’s Climate is also Dynamic Climate Change (or Variation) Characterizes Earth’s History E.g., Eocene temperature was 4 – 6 °C warmer than today Eocene on Ellesmere Island, far north Canada Images from www.thecanadianencyclopedia.com Modern day on Ellesmere Island, far north Canada Earth’s Climate is also Dynamic Climate Change (or Variation) Characterizes Earth’s History E.g., Eocene seas were 100 - 150 m higher than today Image from www.thecanadianencyclopedia.com Earth’s Climate is also Dynamic Climate Change (or Variation) Characterizes Earth’s History E.g., Milankovitch Cycles –Earth’s changing orbit influences temperature with ~41,000 & ~100,000 yr periodicities Image from Wikipedia (see “Geologic temperature record”) Earth’s Climate is also Dynamic Climate Change (or Variation) Characterizes Earth’s History E.g., Pleistocene glacial and inter-glacial periods Image from Wikipedia (see “Geologic temperature record”) Natural Climate “Forcing” (Physical processes that influence Earth’s avg. temp.) E.g., Pleistocene glacial and inter-glacial periods Image from Wikipedia (see “Geologic temperature record”) Natural Climate “Forcing” Orbital Owing to other planets in our solar system, Earth’s orbit varies over long time scales; e.g., eccentricity varies from 0.005 to 0.058 Hypothetical circular orbit, no eccentricity Image from Wikipedia (see “Milankovitch cycles”) Hypothetical orbit with 0.5 eccentricity Natural Climate “Forcing” Orbital Earth’s axial tilt (obliquity) varies from 22.1° to 24.5° Image from Wikipedia (see “Milankovitch cycles”) Natural Climate “Forcing” Orbital Orbital forcing causes variation in solar heating of the planet (a.k.a. radiative forcing) Image from Wikipedia (see “Milankovitch cycles”) Natural Climate “Forcing” Radiative Image from Wikipedia (see Global Warming) Natural Climate “Forcing” Radiative Earth’s avg. temp. = 14 °C (57 °F) Without the atmosphere’s greenhouse effect it would be about -18 °C (-0.4 °F) Image from: www.grida.no Anthropogenic Causes of Climate Change At regional scales, deforestation leads to drying (and heating), owing primarily to reduced evapotranspiration and water-holding capacity of soil This isn’t very surprising, since clouds that form from transpired water are absent over wide, treeless rivers & their immediate floodplains in the Amazon Basin Image from: http://earthobservatory.nasa.gov Anthropogenic Causes of Climate Change At regional scales, deforestation leads to drying (and heating), owing primarily to reduced evapotranspiration and water-holding capacity of soil E.g., cities in the Brazilian Amazon are warmer and drier than those areas were before they became urban centers E.g., much of Greece is warmer and drier today because of deforestation in earlier millennia These examples are not global, but they demonstrate that humans can alter regional climate patterns Anthropogenic Causes of Climate Change International Panel on Climate Change (IPCC) est. 1988 by the United Nations Taking all the accumulated evidence into account, anthropogenic increases in greenhouse gases are the principal causes of modern global warming; i.e., we are experiencing an anthropogenically enhanced greenhouse effect Image from Wikipedia (see “Greenhouse gas”) Anthropogenic Causes of Climate Change Al Gore (b. 1948) 45th U. S. Vice President Shared Nobel Peace Prize (2007) with IPCC Academy Award (2007) for the documentary film: An Inconvenient Truth Photo from: www.thegeneralist.co.uk Anthropogenic Causes of Climate Change The Keeling Curve Image from NOAA Anthropogenic Causes of Climate Change IPCC predictions are for [CO2] by 2100: 500 to 1000 ppm; with concomitant global temperatures 1.1 to 6.4 °C higher Image from www.epa.gov Kyoto Protocol (1997) Legally binding treaty through 2012 (when ratified by states) intended to enact resolutions from the United Nations’ Framework Convention on Climate Change (1992) to achieve “stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system” Green = signed & ratified Red = signed, but not ratified Grey = non-signatory Image from Wikipedia (see “Kyoto Protocol”) Montreal Protocol (1987) Treaty to enact resolutions from the United Nations’ Vienna Convention on the Protection of the Ozone Layer (1985) to “protect the ozone layer by taking precautionary measures to control equitably total global emissions of substances that deplete it, with the ultimate objective of their elimination” September 2006 Image from Wikipedia (see “Ozone depletion”) – NASA image of largest Antarctic ozone hole ever recorded Declining Glacial Thickness Image from Wikipedia (see “Global Warming”) Feb. 17, 1993 Glacial retreat (loss) on Mt. Kilimanjaro Feb. 21, 2000 Photo of glacial retreat on Mount Kilimanjaro (Feb. 1993 to Feb. 2000) from Wikipedia; Map of Africa from www.admin.uio.no Glacial retreat (loss) in the Alps Photo by K. Harms – looking down the glacial valley below Lämmerenhütte; Switzerland, October 2010 Glacial retreat (loss) in the Alps Photo by K. Harms – looking up the glacial valley below Lämmerenhütte; Switzerland, October 2010 Glacial retreat (loss) in the Alps Photo by K. Harms of Lämmerenhütte; Switzerland, October 2010 Glacial retreat (loss) in the Alps Photo by K. Harms – the remnant glacier above Lämmerenhütte; Switzerland, October 2010 Decreasing oceanic pH Tatoosh Island, Washington Photo from Wikipedia; figures from Wootton et al. 2008 Proceedings of the National Academy of Science Climate Change Impacts Biota Altered expression of traits (owing to phenotypic plasticity; e.g., phenology) Range shifts (especially upslope and to higher latitudes) Adaptation (to changing environment) Extinctions (when range shifts and adaptation fail to keep pace with changing environments) Climate Change Impacts Biota Range map and image of polar bear (Ursus maritimus) from Wikipedia Opinions on Climate Change Do you think human activity is a significant contributing factor in changing mean global temperature? From Doran & Zimmerman (2009) Eos (formerly Transactions of the American Geophysical Union)