Like Jonah, I wrote about global warming today. An e-mail:

Dear Mr. Lowry: …you concede too much when you link carbon emissions to warming. No one knows what is causing whatever warming there might be. (I note here two things: Mars is warming also, and one would be hard pressed to blame on carbon emissions; again, it was much warmer in the Middle Ages then today [hence, the name, Greenland] and that warming would be quite hard to blame on carbon emissions.)

UPDATE:

An e-mail:

“Regarding your post about global warming on Mars, this argument has been attacked by the folks at RealClimate before. See this post and its comments.”