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Climate Change
Photo of glacial retreat on Mount Kilimanjaro (Feb. 1993 to Feb. 2000) from Wikipedia; Map of Africa from www.admin.uio.no
Feb. 17, 1993
Feb. 21, 2000
Image from Wikipedia (see “Climate”)
Temperature
Weather Patterns are Dynamice.g., monthly variation
Image from Wikipedia (see “Climate”)
Precipitation
Weather Patterns are Dynamice.g., monthly variation
Image from Wikipedia (see “Geologic temperature record”)
Climate Change – a shift of average weather across a region
Earth’s Climate is also DynamicClimate Change (or Variation) Characterizes Earth’s History
Image from Wikipedia (see “Geologic temperature record”)
E.g., Eocene temperature was 4 – 6 °C warmer than today
Earth’s Climate is also DynamicClimate Change (or Variation) Characterizes Earth’s History
Images from www.thecanadianencyclopedia.com
Eocene on Ellesmere Island, far north Canada
Modern day on Ellesmere Island, far
north Canada
E.g., Eocene temperature was 4 – 6 °C warmer than today
Earth’s Climate is also DynamicClimate Change (or Variation) Characterizes Earth’s History
Image from www.thecanadianencyclopedia.com
E.g., Eocene seas were 100 - 150 m higher than today
Earth’s Climate is also DynamicClimate Change (or Variation) Characterizes Earth’s History
Image from Wikipedia (see “Geologic temperature record”)
E.g., Milankovitch Cycles –Earth’s changing orbit influences temperature with ~41,000 & ~100,000 yr periodicities
Earth’s Climate is also DynamicClimate Change (or Variation) Characterizes Earth’s History
Image from Wikipedia (see “Geologic temperature record”)
E.g., Pleistocene glacial and inter-glacial periods
Earth’s Climate is also DynamicClimate Change (or Variation) Characterizes Earth’s History
Image from Wikipedia (see “Geologic temperature record”)
E.g., Pleistocene glacial and inter-glacial periods
Natural Climate “Forcing”(Physical processes that influence Earth’s avg. temp.)
Image from Wikipedia (see “Milankovitch cycles”)
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
Hypothetical orbit with0.5 eccentricity
Natural Climate “Forcing”Orbital
Image from Wikipedia (see “Milankovitch cycles”)
Earth’s axial tilt (obliquity) varies from 22.1° to 24.5°
Natural Climate “Forcing”Orbital
Image from Wikipedia (see “Milankovitch cycles”)
Orbital forcing causes variation in solar heating of the planet (a.k.a. radiative forcing)
Natural Climate “Forcing”Orbital
Image from Wikipedia (see Global Warming)
Natural Climate “Forcing”Radiative
Image from: www.grida.no
Earth’s avg. temp. = 14 °C
(57 °F)
Without the atmosphere’s greenhouse
effect it would be about -18 °C
(-0.4 °F)
Natural Climate “Forcing”Radiative
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
At regional scales, deforestation leads to drying (and heating), owing primarily to reduced evapotranspiration and
water-holding capacity of soil
Image from: http://earthobservatory.nasa.gov
Anthropogenic Causes of Climate Change
E.g., cities in the Brazilian Amazon are warmer and drier than those areas were before they became urban centers
At regional scales, deforestation leads to drying (and heating), owing primarily to reduced evapotranspiration and
water-holding capacity of soil
These examples are not global, but they demonstrate that humans can alter regional climate patterns
E.g., much of Greece is warmer and drier today because of deforestation in earlier millennia
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
Photo from: www.thegeneralist.co.uk
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
Anthropogenic Causes of Climate Change
Image from NOAA
The Keeling Curve
Anthropogenic Causes of Climate Change
Image from www.epa.gov
IPCC predictions are for [CO2] by 2100:500 to 1000 ppm;
with concomitant global temperatures 1.1 to 6.4 °C higher
Anthropogenic Causes of Climate Change
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”
Image from Wikipedia (see “Kyoto Protocol”)
Green = signed & ratified
Red = signed, but not ratified
Grey =non-signatory
Kyoto Protocol (1997)
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”
Montreal Protocol (1987)
Image from Wikipedia (see “Ozone depletion”) – NASA image of largest Antarctic ozone hole ever recorded
September 2006
Image from Wikipedia (see “Global Warming”)
Declining Glacial Thickness
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) on Mt. Kilimanjaro
Feb. 17, 1993
Feb. 21, 2000
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
Photo from Wikipedia; figures from Wootton et al. 2008 Proceedings of the National Academy of Science
Decreasing oceanic pH
Tatoosh Island, Washington
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 tokeep pace with changing environments)
Climate Change Impacts Biota
Range map and image of polar bear (Ursus maritimus) from Wikipedia
Climate Change Impacts Biota
From Doran & Zimmerman (2009) Eos (formerly Transactions of the American Geophysical Union)
Opinions on Climate Change
Do you think human activity is a significant contributing factor in changing mean global temperature?