For defining terrestrial carbon sequestration http://www.fossil.energy.gov/programs/sequestration/terrestrial/

For U.S. Climate Change Technology Program http://www.climatetechnology.gov/

For U.S. Global climate change policies
http://www.state.gov/g/oes/climate/
http://www.climatetechnology.gov/library/2003/currentactivities/intro.htm#commitment

Climate Vision -- http://www.energetics.com/climatevision/

USDA Global Change Program Office -- http://www.usda.gov/agency/oce/gcpo/index.htm

Intergovernmental Panel on Climate Change -- http://www.ipcc-nggip.iges.or.jp/