Gorebal Warming, like the previous hole in the Ozone layer, and a myriad of other environmental claims, are made by the Left to further socialism and globalism in the name of establishing a one-world dictatorship of virtue.
They find, or invent, collective problems they claim need collective action to solve. Thus, collectivism, a central tenant and feature of socialism is furthered as a goal. By making the problem global, it argues for a global solution rooted in a need for a one-world government. The end goal is to enact communism globally.
This isn't new and it was essentially the central feature of the International for almost two centuries now.
World War I brought about the collapse of the Second International at its beginning, and a wave of revolutions towards its end. It was in this context that Lenin successfully built the Third (Communist) International.
communistusa.org
www.marxists.org
The problem Communists ran into with the International was it was an in-your-face approach to globalization. People instinctively resisted. So, they replaced it with something less obvious, the global shared problem. In environmentalism they found a near perfect solution.