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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
Weather – the state of the atmosphere at a given time and place
Temperature
Image from Wikipedia (see “Climate”)
Weather Patterns are Dynamic
e.g., monthly variation
Weather – the state of the atmosphere at a given time and place
Precipitation
Image from Wikipedia (see “Climate”)
Earth’s Climate is also Dynamic
Climate Change (or Variation) Characterizes Earth’s History
Climate – meteorological conditions that characteristically prevail in a region
Image from Wikipedia (see “Geologic temperature record”)
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
(orbit influences radiative forcing, i.e., solar input)
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 [e.g., CFCs], 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)