James, what Marx had to say about environment (and "ism") was based on the 19th century science that, inter alia, did have the tools to study the subject area (e.g. the estimation of non-linear equations are possible only with computers) and was biased toward the expansionist "white-man-burden" philosophy. Suffice it to say that the same science produced eugenics and IQ testing.
It is possible to approach environment without petit bourgeois sentimentalism - e.g. as land use - which is the main tool to screw the working class, at least in this country. Studying patterns of land use can give you better insights to social inequality in the US than all culture and identity based approaches combined.
It is interesting that much of today's anti-capitalist rhetoric is expressed in the language of environmentalism. This seems to be a very intelligent way to go. Maintaining that capitalism impoverishes the working class seems untenable nowadays, especially in Western Europe. However, demanding that the environment (or the so-called externalities) are included in the cost-benefit calculus of the capitalist enterprise strikes at the center of the capitalist legitimating myth of efficiency. If we start accounting for the hitherto externalised (i.e. not included in the economic calculus) social and environmental cost of capitalist production - its alleged efficiency will likely burst like the stock market bubble.
wojtek