Life of Riley has a highly useful post of leftist views on the environment and climate change, including podcasts and background material. It’s titled Environmentally aware blogging and podcasting from a determined left perspective. Check it out.
Greenie treehugger sites are great (and indeed, Treehugger itself is indispensable) but most of them either barely mention politics or think that asking Congress to act is what’s needed. What the hard left brings to the discussion is an analysis of the major role capitalism and imperialism play in climate change and how new political structures, specifically socialism, will be needed as we work towards ending global warming.
A top-down worldwide solution is needed, something nearly impossible to do under capitalism. Also, the underpinning of capitalism, the profit motive, currently overrides everything other concern, and that must change. We need to put the long-term health of the planet before the short-term profit making of capitalism.