"The point of no return is no longer over the horizon," warned UN secretary general Antonio Guterres as the 25th climate summit (COP25) opened in Madrid two weeks ago, and the multitude of delegates from more than a hundred countries presumably understood what he meant. But they ignored it anyway.
The "point of no return" arrives in the mid-2030s, when the rising emissions of greenhouse gases (they are still rising, not falling) pushes the amount of carbon dioxide equivalent in the atmosphere up past 450 parts per million. 450ppm of CO2 drives the average global temperature up past +2C (2 degrees higher than the pre-industrial average) and into runaway.
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In diplomatic-speak, what happens then is "dangerous climate change", but that is actually happening already, with carbon dioxide at 405ppm and average global temperature "only" 1.1C higher. We are seeing firestorms in Australia, rising sea levels, catastrophic storms and melting glaciers.
What happens at 450ppm is that the two degrees of warming caused by human beings trigger natural processes ("feedbacks" or "tipping points") that also cause warming – and once they start, human beings cannot stop them. The Big Three feedbacks are the loss of the Arctic Ocean's sea ice cover, the melting of the permafrost zone, and the release of vast amounts of CO2 by the warming world oceans.
Guterres called it "the point of no return" because after that we lose control. The warming will then continue even if human beings eventually stop all of their own emissions. We will be trapped on an "up" escalator that delivers us into a world three, four, even five degrees hotter than the pre-industrial average.
That is exactly where the World Meteorological Organisation predicts we will be by the end of this century if current promises on emissions cuts are kept, but no more is done. Long before the end of the century that would mean the collapse of food production in the tropics and the sub-tropics, famines and huge refugee flows, mass death.
They never spell these things out at the climate summits, but almost everybody there knows them. And yet, once again, they failed to produce a deal that moves the process forward. The best that can be said is that they stopped a concerted attempt by the biggest emitters, led by Brazil and Australia, to gut the proposed rules for a global carbon market.
How can they be so blind to their own long-term interest in survival? The answer, alas, is that our evolutionary past of human beings has not made human societies good at long-term thinking. Moreover, human politics is dominated by those whose interests will be advanced or damaged by what the government does right now, not in 15 years' time. Take Australia, for example.
Australia is the driest continent, and as the heat mounts (much of the country is expecting temperatures in the low to mid-40Cs this week) the number and scale of bush fires has exploded. The biggest blaze, in the Blue Mountains west of Sydney, has already burned over 400,000 hectares and is still growing.
But Australia is also the world's biggest exporter of coal, mostly to China and Japan. Coal-mining only employs 38,000 Australians, but it brings in a lot of money, some of which inevitably ends up as political contributions that link the industry with all the Australian political parties.
That's why, two years ago, Liberal (i.e. conservative) politician Scott Morrison brought a lump of coal into parliament. It was "clean" coal, in the sense that it had been lacquered so that it wouldn't dirty people's hands. Morrison passed it around to his parliamentary colleagues saying "Don't be afraid, don't be scared, it won't hurt you. It's coal."
ScoMo (as the Australian media have nicknamed Morrison, presumably because it sounds a bit like "scum"), is now Prime Minister, and as the country burns he continues to deny any link between burning coal and global heating. He offers his "thoughts and prayers" to the victims of the fires, but insists that climate change is only one of "many other factors" in fuelling the bush fires.
Australian Deputy PM Michael McCormack takes an even more robust line, dismissing climate change as a concern of "raving inner-city lefties". That will not endear him to the hundreds of families who have been burnt out, but there are millions of families who have not yet lost their homes, so this may still be a viable political position.
Of all the major emitters, only the European Union is taking its responsibilities seriously. The rest range from deeply conflicted countries like China and Canada, both aware that climate change is an existential threat but both hugely dependent on fossil fuels, to the outright deniers like Australia, Brazil, Saudi Arabia and the United States.
One by one, we are missing all the exits on the Highway to Hell.
• Gwynne Dyer is the author of Growing Pains: The Future of Democracy (and Work).