The realities of climate changeThe realities of climate change

The balance of evidence suggests that there is a discernible human influence on global climate. IPCC 2nd Assessment Report, 1996.

There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activity. IPCC 3rd Assessment Report 2001

The balance of evidence suggests that there is a discernible human influence on global climate. IPCC 2nd Assessment Report, 1996.

There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activity. IPCC 3rd Assessment Report 2001

S. MulkeyJune 2006

Mechanism of atmospheric forcing

The greenhouse gases

Relative importance

Trends through 2002

The scientific consensus

June 2005

Observed warming

Models predicted the effect of Pinatubo

• Global temperatures rose 1.1oF over the 20th Century.

• Models predict temperature to increase 2.5-10.5oF between 1990 and 2100.

Greenhouse gases are higher now than in 650,000 years

Future shock

Consequences: temperatures will rise 1.5 - 6.0oC

QuickTime™ and aCinepak decompressor

are needed to see this picture.

QuickTime™ and aCinepak decompressor

are needed to see this picture.

Washington DC will change from having about 35 days above 90o F to over 85 days per year by 2050.

Temperature change by 2050

Consequences: redistribution of precipitation

Green • = increasing

Brown • = decreasing

Consequences: Consequences: extreme extreme weatherweather

2004 - 1,717 tornados

Consequences: increased hurricane intensity

Annual power dissipation (PDI) by tropical cyclones compared to September sea surface temperature (SST). Emanuel [Nature, 2005]

When North America was colonized by Western Europeans, Glacier National Park contained more than 120 glaciers. Presently there are 23 glaciers, and by 2050 there will be none.

Consequences:decrease in terrestrial ice

Consequences: decreasing polar ice

• The Northwest Passage will become reality by 2050.

• Decreasing ice amplifies warming

Consequences: amplification from defrosting the permafrost

• Official climate projections do not include CO2 and CH4 emissions from melting permafrost.

• Because of this carbon release, warming will be faster than predicted. (Davidson & Janssens Nature 2006)

IPCC 4th assessment preview: Expect a global 3.0oC minimum increase by 2100. Recent papers put the average closer to 4.0oC

Consequences: Sea level rise

Data adjusted for population growth

Consequences: infectious disease

Consequences: shifting agricultural productivity

Consequences: global species extinction

On the basis of mid-On the basis of mid-range climate-warming range climate-warming scenarios for 2050, scenarios for 2050, 15-37% of species will 15-37% of species will be “committed to be “committed to extinction”extinction” - - Thomas et al. Thomas et al. NatureNature 2004. 2004.

Business as usual: the world in 2075

• Sea level 0.25 meters (about 10 inches) higher

• Millions of human ecological refugees - sea level rise & disasters

• Agricultural productivity will shift up to 10o North in N. America

• Up to 40% of existing biodiversity extinct

• Loss of most coral reefs - ocean warming & acidification

• Increased infectious disease - 800 million with malaria

• Over a third of the Amazon basin progressing to savanna

• Major ecosystems in transition from their present form

• 400 million people living with water shortage

• Increasing severe weather and intensity of tropical storms

[The effects of global warming] “would emerge as if someone had subtly, but progressively, loaded a pair of dice.” - Kerry Emanuel 2005

Rapid climate change: tipping points & uncertainties

• How fast will Greenland melt?

• Will the Antarctic ice shelf come unplugged?

• When will the Atlantic conveyor belt slow down and stop?

• What is the ocean capacity to absorb heat and CO2?

• What is the extent of amplification due to permafrost & sea ice melting?

“The greatest hoax ever perpetrated on the American people.”

- Senator James Inhofe. 2005

“The global environmental effects of the industrial era will cast a long shadow on future generations everywhere, for all time.”

David Orr. 2005. The Last Refuge.