Environmentalism is sometimes seen as a product of prosperity, an approach usually known as the ‘post-materialist’ thesis. But this fails to do justice to the scope of environmentalist movements today; there is also the ‘environmentalism of the poor’ which grows out of distribution conflicts over the use of ecological resources needed for livelihood. Despite the importance of this contradiction, an ecological Marxism has scarcely existed, though attempts have been made to ‘ecologize’ Sraffian economics. Most environmental goods and services, however, are not in the market, hence the importance of the notion of ‘ecological distribution’, i.e. the social, spatial and temporal asymmetries in access to natural resources or the burdens of pollution (whether traded or not). Political economy, the historic name for economics, is nowadays used for those branches of economics that focus on distributional conflicts. The branches of ecological economics (or human ecology) that focus on ‘ecological distribution’ conflicts can likewise be referred to as political ecology. Several arguments can be adduced against economic commensurability (following a lead from Otto Neurath in the debate of the 1920s on economic calculus in a socialist economy). The issue cannot be resolved by bringing externalities into surrogate markets (there cannot be ‘ecologically correct prices’, though there might be ‘ecologically corrected prices’), but only by social activism against depletion of resources and environmental pollution.

In academic political sociology, the rise of environmentalism has been interpreted mainly in terms of the post-materialist thesis.footnote1 From the Marxist perspective, and in general that of the New Left, the first reaction to the explicit social presence of environmentalism in the late 1960s and early 1970s was one of surprise if not repudiation.footnote2 The rise of the German Greens was met by incomprehension. Attempts were made to identify the Greens with Nazi rhetoric on Blut und Boden. (These attempts still continue from non-Marxist quarters, for instance in Luc Ferry’s writings.) The folly of such attacks was evident from the fact that others at the same time had a ‘watermelon’ image of the Greens, as green on the outside, but red inside.

The Marxist neglect of ecology has a long history, going back to Marx and Engels’s own negative reaction to Sergei Podolinsky’s attempt in 1880 to introduce human ecological energetics into Marxist economics. This was a missed opportunity, and the decades of neglect of the study of energy flows by Marxist historiography and economics have continued to this day. Engels’s hasty private notes on the second law of thermodynamics (which he found logically contradicted the first law) were glorified in successive editions of Dialectics of Nature (first published in 1925). If Engels had written, as he might well have done, that the first and second laws were dialectically complementary, this might have become the orthodox interpretation. Engels’s negative comments on Podolinsky’s work in letters to Marx of December 1882 were first published in 1919, and were not questioned until the late 1970s, when my own work on Podolinsky’s ideas (together with J. M. Naredo) was first published.footnote3 This delay was somewhat peculiar, in that Podolinsky’s work had been explicitly praised by Vladimir Vernadsky in the 1920s. Vernadsky wrote that Podolinsky had analysed the energetics of life (life systems being open to the input of energy), and applied these ideas to the analysis of the economy. When The Entropy Law and the Economic Process by Georgescu-Roegen appeared in 1971, asserting the relevance of the second law for economics, any response from Marxist quarters was almost non-existent for twenty years. Even today one may read astonishing declarations. For instance, David Harvey proclaims that neither the second law of thermodynamics nor the inherent sustaining power of ecosystems are ‘helpful at all in explaining the shifting history of human social organization’,footnote4 a frontal attack for no good reason against ecological economics and human ecology from a geographer who might have learned otherwise from Patrick Geddes and Lewis Mumford.

Between (say) 1880 and 1980, there was no school of Marxist environmental-social history combining the study of class conflict with the study of human impact on the environment. There was only Wittfogel, closer to deterministic geography than to Marxist environmental history. Although Marx and Engels were contemporaries of the physicists who established the laws of thermodynamics in the mid nineteenth century, Marxian economics and economic history was based on social and economic analysis alone. In the North American context, at least, an intellectual entry to ecological history (or that part of ecological history which pays attention to the flow of energy in human societies, to the efficiency of its use, to endosomatic and exosomatic consumption of energyfootnote5) was provided by Henry Adams’s ‘Letter to American Teachers of History’ in which he proposed a historical law of exponential growth of energy use.footnote6 The debate on whether growth of the economy goes together with a parallel growth in the use of energy and materials is still very much alive today. One school tends to emphasize the purported ‘dematerialization’ (and ‘de-energization’) of the economy, and would therefore explain the rise of environmentalism as a post-material cultural shift towards appreciation of environmental amenities. This has been the consensus among mainstream environmental and resource economists in the United Statesfootnote7 until challenged by the new ecological economics.footnote8 This latter school, while acknowledging that there are gains in technical efficiency in the use of materials and energy, are nevertheless sceptical as to the possibilities of an ‘angelized’ economy (to use Herman Daly’s expression, which Henry Adams would have appreciated), and tend therefore to worry about ‘the effluents of affluence’ and the depletion of resources.

For Marxists, the introduction of ecology into historical explanation has been resisted perhaps because of the fear that this could ‘naturalize’ human history. There have of course been no lack of attempts in this direction, from Malthus’s law of population onwards. Indeed, ecological concepts, or at least terms (such as Lebensraum, for instance) have been used with criminal intent and to devastating effect against fellow human beings. Social Darwinism is still very much alive, as for instance in Garrett Hardin’s ‘lifeboat ethics’. Nevertheless, to introduce human ecology into history does not so much ‘naturalize’ human history as ‘historize’ ecology.

The direct endosomatic energy intake for human livelihood is indeed genetically determined, even if in today’s world some people starve while, through energy-intensive farming and a high intake of meat, the rich consume many more calories to feed themselves. But human ecology is different from the ecology of other animals in several crucial respects: a) Humans lack genetic instructions on the exosomatic consumption of energy and materials. Exosomatic consumption depends not on ‘nature’ but on economics, politics, and culture, and exhibits large differences as between rich and poor. The natural sciences allow us to describe such facts of ecological distribution, but they do not provide explanations. b) As regards demography, although the growth of human populations follows Verhulst’s logistic curve, human demography is much more ‘self-conscious’, and depends on social structures.footnote9 c) Finally, human territoriality is politically constructed, a fact which is obvious when considering the issue of freedom (or lack of freedom) of migration. Ecologists are able to explain the patterns of migration of birds and other animals, but in order to explain the migration of humans we must go to the faculties of economics, politics and law. Ethological analogies are faulty. For instance, migration from Morocco into Spain is almost totally forbidden, while migration between Sweden and Spain is now completely free, within the European Union.

Introducing ecology into the explanation of human history thus does not imply in the least the naturalization of human history, or the idea that ‘capitalism and the market system are natural outgrowths of human propensities’. On the contrary, introducing ecology into history historicizes ecology.footnote10 Ecology is not a longue durée backdrop to human history; sometimes it changes more rapidly than economic or political systems, as in many regions of America after 1492, and perhaps again today with global warming and mass biological extinction.