The author of today’s post, Mark MacLeod, is Director of Special Projects for the national climate campaign at Environmental Defense.

This has been Climate Week in New York and D.C., starting with the U.N. conference on Monday, then the Clinton Global Initiative annual meeting Wednesday through Friday, and finally the White House Major Economies Meeting today and tomorrow.

This week’s focus on global warming has prompted a flurry of letters around Washington, D.C. urging President Bush to support mandatory caps on greenhouse gas emissions.

On Monday, Senate Majority Leader Harry Reid and Speaker of the House Nancy Pelosi co-signed a letter to President Bush, calling on him to support mandatory limits on greenhouse gas emissions, both nationally and internationally.

The next day, Senators Joe Biden and Olympia Snowe sent a letter to President Bush urging him to support mandatory national caps, and a post-2012 framework for binding commitments for all major emitting countries.

Yesterday, Senator John Kerry added his voice to the chorus, sending President Bush a letter calling for mandatory domestic caps, and leadership in reaching an international agreement.

The heat is on – in more ways than one.