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Human Impacts
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Deforestation / Fragmentation
Pesticides
Global warming
Depletion of ozone layer
Acid rain
Global Warming
• 1990s was the hottest decade, 1998 hottest
year on record (since 1861)
• ~ 10% loss of snow cover since 1960s.
• Sea level has risen by 10-20 cm during the
1900s.
• El Niño has been more frequent, persistent,
and intense since 1970s (relative to past 100
years).
Global Warming (Land Surface)
Global Warming (Ocean)
Levitus, S., Antonov, J.I., Boyer,
T.P., & Stephens, C. (2000)
Warming of the World Ocean.
Science, 287, 2225-2229.
Some Factors Influencing Climate
• Fluctuations in solar energy
• Orbital parameters
• Planetary albedo (reflectivity)
– Aerosols (things in the air)
– Ice, water, land, plant surfaces
• Anthropogenic factors (Greenhouse Effect)
– Burning of fossil fuels
– Deforestation
The Greenhouse Effect
http://cdiac.esd.ornl.gov/trends/co2/graphics/sio-mlgr.gif
Other Greenhouse Gasses
Global Warming: Causes
Global Warming: Human Influence
• “Our ability to quantify the human influence on
global climate is currently limited because the
expected signal is still emerging from the noise of
natural variability…’” – 1995 IPPC Summary,
cited by 2001 EPA global warming web site
• “In the light of new evidence . . . most of the
observed warming over the last 50 years is likely
to have been due to the increase in greenhouse gas
concentrations.” – 2001 IPCC Summary
Global Warming: Predictions
• IPCC 1995
– 1.0 – 3.5 °C
– 1.8 – 6.3 °F
• IPCC 2001
– 1.4 – 5.8 °C
– 2.5 – 10.4 °F
Global Warming: Predictions
Uncertainty Analysis of Global Climate Change Projections,
M. D. Webster, et al. Joint Program on the Science and Policy
of Global Change, MIT
Schneider, S.H. 2001. What is 'dangerous' climate change?
Nature 411: 17 – 19.
Global Warming: Impacts
Changes in
Phenomenon
Confidence in
observed
changes
Confidence in
projected changes
 max. temps over
nearly all land areas
Likely
Very likely
 min. temps,  frost
Very likely
days over nearly all land
areas
Very likely
 intense precipitation
events
Likely over many
N. hemisphere
mid- to high
latitude areas
Very likely over many
areas
 summer continental
drying and risk of
drought
Likely in a few
areas
Likely over most midlatitude continental
interiors.
 in tropical cyclone
Insufficient data
Likely in some areas
Demographic Changes
An increase in temperature of 4 °C would require
a shift in mean temperature threshold of 35 SD!
Janzen, F. J. 1994. Climate change and temperature-dependent sex determination in reptiles.
Proceedings of the National Academy of Science of the United States of America 91:7487–7490.
Geographic Range Changes
N range limit of 52 spp.
65% expanded N
34% stable
2% contracted S
Parmesan, C., N. et al. 1999. Poleward shifts in
geographical ranges of butterfly species
associated with regional warming. Nature
399:579–583.
Altitudinal Changes
• Climate changes more rapidly with elevation (1° C
/ 160 m) than it does with latitude (1° C / 150 km
• For 9 species in Swiss Alps with detailed records:
– Observed rate of upward shift 1–4 m per decade.
– Predicted rate of upward shift 8–10 m per decade based
on the change in mean temperature over the last 90
years
• May indicate that these plants are unable to
respond successfully to more rapid climate
change.
Grabherr, G., M. Gottfried & H. Pauli. 1994. Climate effects on mountain plants. Nature 369:448
Phenological Changes
Breeding date
Pied Flycatcher
13 days
24 Slater 1999
Breeding date
Tree Swallow
5–9 days
33 Dunn & Winkler 1999
Breeding date
Great Tit
11.9 days
27 McCleery & Perrins 1998
Breeding date
2 bird species
30 days
35 MacInnes et al. 1990
Breeding date
Mexican Jay
10.1 days
27 Brown et al. 1999
Migration date
4 bird species
11.9 days
50 Mason 1995
Migration date
39 bird species
5.5 days
50 Oglesby & Smith 1995
Migration date
American Robin
14 days
19 Inouye et al. 2000
McCarty, J. P. Ecological Consequences of Recent Climate Change. The Journal of the Society for Conservation Biology 15 (2), 320-331.
Phenological Changes
Inouye, D. W., et al. 2000. Climate change is affecting altitudinal migrants and hibernating species. PNAS 97:1630–1633.
Global Warming Consequences
Kiesecker, J.M., Blaustein, A.R., & Belden, A.K.
(2001) Complex causes of amphibian population
declines. Nature, 410, 681-684.
Global Warming Consequences
Kiesecker, J.M., Blaustein, A.R., & Belden, A.K. (2001) Complex causes of amphibian population declines. Nature, 410, 681-684.
What’s Being Done to Control
Global Warming?
• International policy
• National policy
• Personal policy
Greenhouse Gas Emissions
http://www.epa.gov/globalwarming/emissions/individual/index.html
Greenhouse Gas Emissions
• Emissions per person have increased about 3.4%
between 1990 and 1997.
• 82% of these emissions are from burning fossil
fuels to generate electricity and power our cars.
• You can affect 32% of the total emissions per
person
– electricity, waste production, personal transportation
• The other 68% of emissions are affected by
industry
– types of offices we use, how our food is grown, etc.
http://www.epa.gov/globalwarming/emissions/individual/index.html