The Academies of Science of United States (and 20 other Nations)

United States United Kingdom Germany Japan Canada China France

India Russia Italy Australia Belgium Brazil Caribbean

Indonesia Ireland Malaysia Mexico New Zealand South Africa Switzerland

http://www.nationalacademies.org/includes/G8Statement_Energy_07_May.pdf
http://nationalacademies.org/onpi/06072005.pdf

http://www.royalsociety.org/displaypagedoc.asp?id=13619

http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=11676

American Association for the Advancement of Science
(i.e. The guys who publish the Journal of Science, The most highly syndicated peer reviewed science journal in the world)
http://www.motherjones.com/blue_marble_blog/archives/2007/02/3630_aaas_statement.html

American Geophysical Union

(a scientific organization with over 50,000 members, mostly earth scientists)

http://www.agu.org/sci_soc/policy/positions/climate_change2008.shtml

United States Pentagon

http://money.cnn.com/magazines/fortune/fortune_archive/2004/02/09/360120/index.htm

http://observer.guardian.co.uk/international/story/0,6903 ...
http://www.grist.org/pdf/AbruptClimateChange2003.pdf

Exxon Mobil (Although one would imagine this is only because their hand was forced)

http://www.exxonmobil.com/Corporate/news_speeches_20070213_RWT.aspx

http://www.nytimes.com/2007/02/14/business/14exxon.html?pagewanted=print

http://www.msnbc.msn.com/id/16593606/

Even the American Association of Petroleum Geologists

http://dpa.aapg.org/gac/statements/climatechange.cfm

http://www.youtube.com/watch?v=SZurM7c19ig

The mainstream agreement in the scientific community is rather clear.

_

Even the Bush Administration agrees now.

http://blogs.wsj.com/environmentalcapital/2008/05/29/white-house-humans-very-likely-causing-warming/