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Global Warming The EvidencePotential for change? Can anthropogenic change

be separated from natural change? Can the world collectively

decide to do something about global carbon dioxide emissions?

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What causes Global Warming? Addition of greenhouse gases to

atmosphere Main culprit is CO2

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7CS Fig. 17.19

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8CS Fig. 17.20

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CS Fig. 17.23

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CS Fig. 17.18

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Bubbles in glacialice preserveair of past cent-uries:

Tell us what CO2

concentrationswere like beforethe industrialrevolution

Edmonds, 1999

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Longer records

Global Temperatures projected to rise3 to 9 °F

Edmonds, 1999

Consequences?http://www.enviroweb.org/edf/index.html

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16CS Fig. 17.22

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Historical Data

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Change in surfacetemperatures,1979-1998

Change in freeatmosphere (<5 miles)temperatures,1979-1998

Note: deep red is ~1 °F warmer, deep blue is ~1 °F cooler

The debate rages on!

Newspaper articles show scientists do not all agree as to whether the planet is currently warming

The vast majority of scientists, however, do agree that the planet is warming due to additions of greenhouse gases to the atmosphere

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Natural Climate Change

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Natural Climate Change

Cooling of the last 100 million years, warming of the last 20,000 years well documented

Short term change (10’s to 1000’s of years) less well documented

Short term change less well understood Role of oceans unclear Role of tides (1800 year cycle) just

coming into question

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The Sulfate “Fingerprint”

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Best evidence that recent warming is anthropogenic

From Mannand others,Nature, 1998

Three years in the1990’s are thewarmest in theNorthern Hemisphere,by far, of the last400 years!

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Where we stand:

What we do know: Atmospheric CO2

concentrations have risen 50% since the beginning of the industrial revolution

With business as usual, CO2 concentrations will continue to rise

CO2 is a strong greenhouse gas

What we’re pretty sure of: Surface temps in

the Northern Hemisphere are the highest they’ve been in 400 years

Climate models do a good job of predicting the impact of CO2 rise

What we’re not sure of: Surface temps

have risen more in the last 25 years than they would have without CO2 increases

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Change in Minnesota“Recent research indicates a warming trend in Minnesota. A study of the climate record at Fort Snelling shows an increase of 2.9°F in average annual temperature between the 1860s and 1987, almost three times the worldwide average. Analyses of more than a hundred temperature-depth profiles in North America show that ground latitudes comparable to Minnesota’s indicated ground warming of up to 3.6°F.”

From “Playing with Fire, Global Warming in Minnesota” 1999; data from Baker and Skaggs, 1989

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MN Biomes at risk

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Change in Lake Superior

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CS, page 390

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Bush Rejectionof Kyoto Protocol

May 2001 USA Europeans angry

Edmonds, 1999

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CS Fig. 17.23

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FCCC

The ultimate objective of the Convention … is to achieve…

stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent

dangerous anthropogenic interference with the climate system.

33Developed and transitional countries

Edmonds, 1999

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Kyoto Protocol:Annex 1 countries reduce emissions by average of 5.2%

Edmonds, 1999

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The End

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