... But if, for the hell of it, we can imagine an oracular, though fully digitised, historian a century hence - let's call her Sibyl - looking back at the first five years of the millennium, and marvelling at the the obtuseness of the generation that failed to see The Writing On The Wall, what would it be about the noughties that she would single out as glaringly ominous?
Well, Sibyl would say, there was the teeny matter of the beginning of the end; of planet Earth, that is, the last chance of reversing the irreversible damage that has been done to the ecosystem, beside which all the rest of its problems were small potatoes. Short of taking the current president of the United States by the scruff of the neck and dunking his head deep into the rapidly melting Arctic ice cap, what more did the Earth need to do to make someone listen to its cry for help? But this was the decayed decade, when everything that urgently needed to be done to reverse carbon emissions was identified, documented, articulated - and then systematically obstructed by the power that was disproportionately responsible for the damage. When the rest of the world shouted "Emergency", America chanted back "Growth". So it got the growth of a malignant tumour.

The decade when coral reefs turned pallid and died; when Alaskan caribou butted their heads against pipelines; when what seemed like a marginal rise in oceanic temperatures translated into hurricanes that ate entire shorelines, was also the decade of the Hummer. Just as Paul Fussell identified the Jeep - light, speedy and tough - as the symbol of the war that America wanted to fight in the 1940s, so the Hummer will forever get remembered as the Supersize emblem of imperial hubris in the noughties: comical in its swaggering, pseudo-military fantasy; obese sheet-metal in denial; the self-dooming guzzler to end all guzzlers; blitzkrieg at the shopping mall - while the real thing - Humvees with teenagers in uniform - get taken out by rocket-propelled grenades in Falluja.

It was the time when the well-heeled of the well-off world gave up smoking, but the planet didn't. On any given day, satellite cameras would have captured the pitiful remnants of rainforests from Amazonia to central Africa to Indonesia, all burning. The charred land would give a few more years of subsistence; then, without vegetation to secure it, the eroded soil would turn to fine, barren dirt and be blown away by the unimpeded winds. From the satellite's orbit, a great island such as Madagascar, which was once predominantly forested, would read as raw, denuded red as its rivers became clogged with silt. The Earth was beginning its transformation into the Other Red Planet.

But, then, what were the impoverished wasteland populations who subsisted at the edge of the forests supposed to do, since their own numbers had risen at a historically unprecedented rate, putting intolerable pressure on finite resources? The separation of the world's peoples into extremes of rich and poor, those regions that managed to contain population growth and those that did not, engendered two kinds of experience of what it meant to live as a human on the planet. Asian countries prospered in direct proportion to the success of their demographic stabilisation; African and Latin American populations descended into a cycle of ever greater misery, which neither the Malthusian checks of Aids, insect-born diseases, famine and wars, nor even the philanthropy of greying rock stars could do much about.

Looking back at this time of lengthening shadows, Sibyl's digital memory inadvertently took her back way beyond the Noughties to a moment, two centuries earlier in the history of the western world, which was filed poignantly under "The Enlightenment". Apparently, in that period men of good faith and powerful minds had actually believed that once humanity was liberated from credulousness and governed by reason (and this, they quaintly supposed, could only be a matter of time), then cruelty, tyranny, superstition, ignorance, destitution and injustice would vanish from the face of the earth. A good many of these optimists had duly perished in the wars and revolutions which, moloch-like, had devoured vast armies and populations, and which had dampened somewhat this touching belief in the inevitability of better times. But for a century or two, notwithstanding the waves of military massacre and civilian genocides with which modern history was regularly punctuated, there were still those who clung to a high-minded vision of a world in which toleration would be the norm rather than the aberration; in which children would be nurtured and educated; in which women lived their lives as partners and equals rather than as servants and subjects of men, and in which the governing class worked for the benefit of the governed rather than for itself....