What follows is rather like the famous courtroom scene in Orson Welles’s The Lady from Shanghai (1947).footnote1 In that noir allegory of proletarian virtue in the embrace of ruling-class decadence, Welles plays a leftwing sailor named Michael O’Hara who rolls in the hay with femme fatale Rita Hayworth, and then gets framed for murder. Her husband, Arthur Bannister, the most celebrated criminal lawyer in America, played by Everett Sloane, convinces O’Hara to appoint him as his defence, all the better to ensure his rival’s conviction and execution. At the turning point in the trial, decried by the prosecution as ‘yet another of the great Bannister’s famous tricks’, Bannister the attorney calls Bannister the aggrieved husband to the witness stand and interrogates himself in rapid schizoid volleys, to the mirth of the jury. In the spirit of Lady from Shanghai, this essay is organized as a debate with myself, a mental tournament between analytic despair and utopian possibility that is personally, and probably objectively, irresolvable.

In the first section, ‘Pessimism of the Intellect’, I adduce arguments for believing that we have already lost the first, epochal stage of the battle against global warming. The Kyoto Protocol, in the smug but sadly accurate words of one of its chief opponents, has done ‘nothing measurable’ about climate change. Global carbon dioxide emissions rose by the same amount they were supposed to fall because of it.footnote2 It is highly unlikely that greenhouse gas accumulation can be stabilized this side of the famous ‘red line’ of 450 ppm by 2020. If this is the case, the most heroic efforts of our children’s generation will be unable to forestall a radical reshaping of ecologies, water resources and agricultural systems. In a warmer world, moreover, socio-economic inequality will have a meteorological mandate, and there will be little incentive for the rich northern hemisphere countries, whose carbon emissions have destroyed the climate equilibrium of the Holocene, to share resources for adaptation with those poor subtropical countries most vulnerable to droughts and floods.

The second part of the essay, ‘Optimism of the Imagination’, is my self-rebuttal. I appeal to the paradox that the single most important cause of global warming—the urbanization of humanity—is also potentially the principal solution to the problem of human survival in the later twenty-first century. Left to the dismal politics of the present, of course, cities of poverty will almost certainly become the coffins of hope; but all the more reason that we must start thinking like Noah. Since most of history’s giant trees have already been cut down, a new Ark will have to be constructed out of the materials that a desperate humanity finds at hand in insurgent communities, pirate technologies, bootlegged media, rebel science and forgotten utopias.

Our old world, the one that we have inhabited for the last 12,000 years, has ended, even if no newspaper has yet printed its scientific obituary. The verdict is that of the Stratigraphy Commission of the Geological Society of London. Founded in 1807, the Society is the world’s oldest association of earth scientists, and its Stratigraphy Commission acts as a college of cardinals in the adjudication of the geological time-scale. Stratigraphers slice up Earth’s history as preserved in sedimentary strata into a hierarchy of eons, eras, periods and epochs, marked by the ‘golden spikes’ of mass extinctions, speciation events or abrupt changes in atmospheric chemistry. In geology, as in biology and history, periodization is a complex, controversial art; the most bitter feud in nineteenth-century British science—still known as the ‘Great Devonian Controversy’—was fought over competing interpretations of homely Welsh greywackes and English Old Red Sandstone. As a result, Earth science sets extraordinarily rigorous standards for the beatification of any new geological division. Although the idea of an ‘Anthropocene’ epoch—defined by the emergence of urban-industrial society as a geological force—has long circulated in the literature, stratigraphers have never acknowledged its warrant.

At least for the London Society, that position has now been revised. To the question, ‘Are we now living in the Anthropocene?’, the twenty-one members of the Commission have unanimously answered ‘yes’. In a 2008 report they marshalled robust evidence to support the hypothesis that the Holocene epoch—the interglacial span of unusually stable climate that allowed the rapid evolution of agriculture and urban civilization—has ended, and that the Earth has now entered ‘a stratigraphic interval without close parallel’ in the last several million years.footnote3 In addition to the build-up of greenhouse gases, the stratigraphers cited human landscape transformation, which ‘now exceeds [annual] natural sediment production by an order of magnitude’, the ominous acidification of the oceans, and the relentless destruction of biota.