All treaties must be approved by the Senate. Was this treaty approved?
The agreement was weak and not a treaty because the Republicans in the Senate would not have ratified a treaty, just as they failed to ratify Kyoto. If any Republicans thought this was a swell idea but just wasn't binding enough they could enter into a second, more aggressive binding agreement with whatever parties they like. Nobody thought this was a great agreement, it was too weak and timid, but it was the strongest agreement we could make without the Senate.
Healthy debate is healthy.