There are no "working alternatives" under capitalism. I hate to sound like an old-fashioned Marxist, but this is the truth. Capitalism is deeply rooted in automobile production based on the internal combustion engine. It initiated the cold war just so it could penetrate the closed markets of the USSR, China, et al. Now that it has, it is hastening global warming which threatens the basis for continued existence of the capitalist system itself. This is what as known in Marxist jargon as a _contradiction_. The mainstream greens have answers to all these problems, but none of them address the underlying question of the means of production. That is why Marxists have something unique to say about the problem, since our approach is rooted in political economy rather than in moral exhortation.
Louis Proyect
(http://www.panix.com/~lnp3/marxism.html)