A variety of sources to help:
A starting debate from Free Market Net nd a real player presentation.
IPCC, the American EPA, New Scientist, Globalwarm and The Tiempo Climate Cyberlibrary are all extensive starting points.

The School of Ocean Sciences from The University of Wales Bangor provides an interesting lecture/thought exercise.

You may wish to do your own environmental (including carbon) audit, Winchester City Council.

You may also wish to think about human health, agriculture and transportation. Remember green organisations such as Greenpeace and Friends of the Earth.

These may in fact steer you in one direction so please consider the following as well, prominent sceptics, from the BBC, American Scepticism a site with many links, Association of British Drivers, motorists again, Bush's original stance and an extensive list of links from both persuasions.