The UK Guardian has published an excellent summary of why no deal is better than a bad deal (in the words of Desmond Tutu). It is all about the science. On current carbon reduction commitments, the stated G-8 goal of keeping temperture to no more than a 2 degree temperature rise would be overshot by a full degree. The article doesn't mention that a global average temperature rise of 3 degrees puts us into a scenario of self-accelerating, unstoppable run-away global warming.
In any event, meaningful and deeper GHG cuts are urgent. If Obama has some of those in his back-pocket we might be able to see a meaningful deal here. But the rich countries offering money and leaning hard on the poor and most vulnerable to take a bad deal is an ugly picture. I know the meek are supposed to inherit the earth. Soon, please.