Hi
I'm a former staffer in the US Senate. The president wouldn't decide on his own whether or not to ratify a treaty--that's decided by our Senate. Our Constitution (article II, sec. 2, yes I had to look that up--
http://www.house.gov/Constitution/Constitution.html) requires a 2/3 majority for ratification. It would take a great deal of political will for that to happen, and seems unlikely, especially if the Republicans retain control of the Senate or there isn't a wide margin for the Democrats (but stranger things have happened). If you look at his campaign website, it says he'll "re-engage" on climate change. See also
http://www.globalwarming.org/article.php?uid=622 and
http://www.iht.com/cgi-bin/generic.cgi?template=articleprint .tmplh&ArticleId=513306, which asserts that even environmentalists admit that now we couldn't comply with the terms of Kyoto.
My understanding is that Russia is heading towards ratifying it--http://forests.org/articles/reader.asp?linkid=31890.
BTW, keep up the good work, Europe! I'll be at the polls in November (if the terrorists or some accident don't get me first, and assuming they're not postponed!)