Human Impacts

• 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.

Changes in Phenomenon

Confidence in observed changes

Confidence in projected changes

max. temps over nearly all land areas

Likely Very likely

min. temps, frost days over nearly all land areas

Very likely 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 mid-latitude continental interiors.

in tropical cyclone precipitation

Insufficient data for assessment

Likely in some areas

Global Warming: Impacts

Demographic Changes

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.

An increase in temperature of 4 °C would require a shift in mean temperature threshold of 35 SD!

Geographic Range Changes

N range limit of 52 spp.65% expanded N34% stable2% 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 ChangesBreeding 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