The Bushies were annoyed that Clinton came to Montreal to try to move things along, so they took their toys and stormed out:

Two weeks of treaty talks on global warming neared an end today with the world’s current and projected leaders in emissions of greenhouse gases, the United States and China, still refusing to take any mandatory steps to avoid dangerous climate change.

The Bush administration was sharply criticized by environmental groups for walking out of a round of informal discussions shortly after midnight that were aimed at finding new ways of curbing gases beyond steps taken so far.

Lovely.