Karl Marx has long been criticized for his so-called ecological "Prometheanism"—an extreme commitment to industrialism, irrespective of natural limits. This view, supported even by a number of Marxists, such as Ted Benton and Michael Löwy, has become increasingly hard to accept after a series of careful and stimulating analyses of the ecological dimensions of Marx's thought, elaborated in Monthly Review and elsewhere. The Prometheanism debate is not a mere philological issue, but a highly practical one, as capitalism faces environmental crises on a global scale, without any concrete solutions. Any such solutions will likely come from the various ecological movements emerging worldwide, some of which explicitly question the capitalist mode of production. Now more than ever, therefore, the rediscovery of a Marxian ecology is of great importance to the development of new forms of left strategy and struggle against global capitalism.… Yet there is hardly unambiguous agreement among leftists about the extent to which Marx's critique can provide a theoretical basis for these new ecological struggles.… This article… [takes] a different approach… [investigating] Marx's natural-scientific notebooks, especially those of 1868, which will be published for the first time in volume four, section eighteen of the new Marx-Engels-Gesamtausgabe(MEGA).