Forcing due to human, rather than natural, factors. Such factors include increased greenhouse gas concentrations associated with fossil fuel burning, sulphate aerosols produced as an industrial by-product, human-induced changes in land surface properties among other things.
Technical Note: We have just upgraded the blog software. It looks ok, but please let us know (contrib -at- realclimate.org) if there are any problems. Update: enabling comment preview caused unacceptable loads on the server, possibly because it conflicts in some way with caching. Any suggestions for a pop-up previewer that might work better would be appreciated!
