One thing that's useful when talking about Global Warming, is to look back at the original Club of Rome (a premier international think tank) report on to how to unite the world under a One World Government i.e. The UN. They said was important to find an enemy that was an enemy to every country, so as we could all fight against it and be united.
Back in 1992 they published a major report entitled " The First Global Revolution" . Here is a quote from that report, " in searching for a new enemy to unite us, we came up with the idea that pollution, the threat of global warming, water shortages, famine, and the like would fit the bill" . Here is another quote from " The First Global Revolution". , " It would seem that humans need a common motivation, namely a common adversary to organize and act together in the vacuum; such a motivation must be found to bring the divided nations together to face an outside enemy, either a real one or else one imagined for this purpose". The Club of Rome works with the United Nations to develop Policy Guidance Documents, which the U.N. uses in creating its policies and programs. Here is a link and don't forget to read the partial list of members of The Club Of Rome, it is very interesting and not surprising.
http://green-agenda.com/globalrevolution.html