"Depend upon it, sir," said Samuel Johnson, "when a man knows he is to be hanged in a fortnight, it concentrates his mind wonderfully". We do indeed have to depend upon the Cop26 summit proving Johnson right, and that the threat of extinction will concentrate the collective mind.
There are, at least, some precedents. One of them is, ironically, the origin of the great fear that has now been displaced by climate change: nuclear war.
Over Christmas in 1938, two physicists, Lise Meitner and her nephew Otto Frisch, had a startling insight. They realised that if you bombarded a uranium nucleus with a neutron, it could split into two, releasing a great amount of energy.
It very quickly dawned on scientists that this could become a chain reaction, producing more and more energy. That process could, in theory, be harnessed to make a bomb of unprecedented destructiveness.
In the spring of 1940, Frisch and Rudolf Peierls, having, like Meitner, fled from the Nazis, arrived in Birmingham. There they figured out something even more alarming – a lump of uranium-235 the size of a golf ball would be enough to make such a bomb.
An even darker thought followed – if they had worked this out, then surely the brilliant colleagues they had left behind in Germany must have done the same. Hitler might well be working on an atomic bomb.
This was, as Jewish people already knew, an existential threat. If Hitler had the bomb and his enemies did not, he would certainly use it. "As a weapon," Frisch and Peierls warned Winston Churchill, "the super-bomb would be practically irresistible". They argued the imperative of developing an atomic bomb as a "counter-threat".
Extraordinary
What happened next was an extraordinary concentration of the mind. Churchill, who himself had already foreseen the possibility that the splitting of the atom could lead to a new and fearful kind of weaponry, alerted US president Franklin D Roosevelt.
Out of this dread came a staggering achievement. The Manhattan Project really got under way in September 1942. The first atomic bomb was exploded less than three years later, in July 1945.
The horrors of Hiroshima and Nagasaki make it hard to celebrate this achievement. But it was, in itself, stunning.
Creating the atomic bomb was actually much more difficult than the scientists had imagined. It required an unprecedented concentration of industrial might, scientific brilliance, governmental commitment and vast public resources.
The reason all of this came together was existential dread: terror of the Nazis and what they would do if they got the bomb first. The prospect of being hanged in a fortnight made what was scarcely possible an achievable reality.
Perhaps humankind needed a holiday from existential anxiety. But the effusion of greenhouse gases did not take a vacation – it just kept going
The great irony, of course, is that this remarkable accomplishment in fact added to the common store of dread. Nuclear weapons, initially a guarantor against extinction, became themselves the bearers of the threat that humanity might obliterate itself.
I sometimes wonder whether one of the deep-lying reasons for the failure of governments and societies to acknowledge the peril of climate change was a kind of dread fatigue.
Everyone who lived through the cold war also lived with a burden of anxiety: the knowledge that an apocalyptic conflagration would trigger the nuclear winter in which most life on Earth would perish. It was a constant background noise that, at moments of crisis, came to the fore and became overwhelming.
It was perhaps unfortunate that the first report of the Intergovernmental Panel on Climate Change was published in 1990, just after the fall of the Berlin Wall. One burden of terror was being lifted, but here was another coming along right on cue to take its place.
Existential anxiety
Perhaps it was natural to think: give us a break. Perhaps humankind needed a holiday from existential anxiety. But the effusion of greenhouse gases did not take a vacation – it just kept going.
Maybe there has also been a paradoxical hangover from the cold war – the worst did not happen. The hard rain did not fall. The eve of destruction was not followed by the dark night of annihilation.
Maybe the period between 1989 and the Paris Agreement of 2015 can be seen as humanity’s long exhale, a sigh of relief that the great danger had apparently passed and we were safe now.
There was a deep desire not to know this was the ultimate false sense of security. It was a pleasant illusion to imagine that, since we got away with the game of chance that was mutually assured destruction, we would get away with every other form of dicing with death.
Indulgence in that illusion has led us to the present crisis. The question that now faces the world is a stark one: can humans concentrate their collective minds without an external enemy?
Survival demands that we be afraid, not of each other, but for each other, and for all the others not yet born
The great fusions of politics, technology, industry and science – like the Manhattan Project and the Apollo moonshot – have been driven by warlike competition.
Without the fear of the Nazis, the atom bomb would not have been developed at such dizzying speed. Without the space race between the Americans and the Soviets, there would have been no man on the moon.
A pessimist might say that this is precisely the problem with climate change. There is no Them, only an Us. We are our own worst enemy, and we have to be our own bogeyman. We have to scare ourselves into action.
It is war that has typically speeded up history by galvanisng the idea of a threat that must be countered, whatever the cost. It is competition for dominance that has spurred governments to undertake the seemingly impossible.
But now we face a threat that cannot be countered by competition between nations. It can be met only by co-operation on a truly global scale. Survival demands that we be afraid, not of each other, but for each other, and for all the others not yet born.
What we know, however, is that the concentration of the mind produces amazing results. If political systems really want to, they can harness science, technology, government, economics and industry to the same wagon. And then things can move with extraordinary rapidity.
Can that willpower be generated without war?
More than a century ago, George Bernard Shaw, in Man and Superman, had the Devil suggest that "in the arts of life, man invents nothing, but in the arts of death, he outdoes nature herself". But we can no longer outdo, or outrun, nature.
If half the money, ingenuity and energy that has been devoted to the arts of death is channelled into the rapid decarbonisation of the global economy, it will be achieved.
The gallows we have built for ourselves does not have to be ascended. We have the power, seldom granted to those who have committed capital crimes against nature, to grant ourselves a reprieve.