Are you really, truly "just curious" or is it that you really, truly don't want to ever give credit to President Bush where it is due?
For if you are really, truly "just curious", the answer to your question is that President Clinton signed some great number of Executive Orders which compelled federal agencies to behave *as if* the Kyoto Global Warming treaty had been ratified.
Clinton signed these XO's such that each one had the effect of enacting some small part of Kyoto, with the cumulative effect being that Kyoto was very much in play in the U.S. up until President Bush began repealing those XO's with new Orders of his own.
Of course, this answer is only going to satisfy you if you were honestly being "just curious" above. No doubt you'll find some way to ignore or dismiss the truth if it turns out that you weren't being honest about your alleged curiosity above.