I just read this piece over at Economist’s View and here’s my solution to the global coordination problem.
Set up an international carbon tax and direct the revenue to an overseeing organization. (If cap and trade can generate revenue for government that could work too.) The funds should then be dedicated to carbon mitigation and climate change adaptation — with the rules deliberately set so there is a generous annual transfer from developed to developing countries. Finally, any country that turns out to be faking things like carbon offsets will have the funds that flow to government decreased so that international monitoring of offsets and similar policies can be funded
The basic idea that I think would be very useful is to take the revenue from a carbon tax — or cap and trade — and use that revenue to deal with the issue of aiding the transition for developing countries.