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The Controversy Basic temperature and CO 2 data are not in dispute • Controversy focuses on whether or not warming trend is anthropogenic – Earth’s temperature has fluctuated in the past – Could be part of a natural cycle Warming may not be caused by CO 2 • Vast majority of climate scientists believe anthropogenic contribution to temperature increase is substantial

The Controversy

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The Controversy. Basic temperature and CO 2 data are not in dispute Controversy focuses on whether or not warming trend is anthropogenic Earth’s temperature has fluctuated in the past Could be part of a natural cycle Warming may not be caused by CO 2 - PowerPoint PPT Presentation

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Page 1: The Controversy

The Controversy

• Basic temperature and CO2 data are not in dispute• Controversy focuses on whether or not warming

trend is anthropogenic– Earth’s temperature has fluctuated in the past– Could be part of a natural cycle– Warming may not be caused by CO2

• Vast majority of climate scientists believe anthropogenic contribution to temperature increase is substantial

Page 2: The Controversy

Some Potential Consequences of Global Warming in 21st Century

• Melting of glaciers and sea ice• Sea level rise (1.5 – 6.5 ft)• Major shifts in precipitation• Increased extreme weather events– Large floods– Greater storm intensity– Large fires

So, what can be done?

Page 3: The Controversy

Ways to Reduce CO2 Emissions

• Renewable/clean energy• Improved energy efficiency• Carbon capture and storage (CCS)• Reforestation• Active management of forests

Page 4: The Controversy

Stabilization Wedges

• Each wedge ~1 Gigaton C per year by 2054

• Possible wedges are:– Improved fuel efficiency

(60 mpg cars)– Energy efficient

buildings– Nuclear power– Alternative energy

sources– CCS

Pacala & Socolow (2004)

Page 5: The Controversy

How much is a Gigaton of carbon?•1 billion tons•Coal 78% C•Each boxcar ~ 100 tons coal•1 GtC = 12 million boxcars coal•Enough boxcars to extend ~5 times around Earth

Coal Cars, WY (photo by Greg Goebel, http://www.vectorsite.net/Yvcol_2m.jpg)

Page 6: The Controversy

Coal Cars, WY (photo by Greg Goebel, http://www.vectorsite.net/Yvcol_2m.jpg)

Tons of CO2 per ton of coal burned?•Atomic wt C = 12, O = 16•1 ton C produces 3.66 tons CO2

•Coal 78% C•1 ton coal produces 2.86 tons CO2

Page 7: The Controversy