The anniversary of the atomic bombing of Japan this week is a time for sombre reflection on the horrors of war. At the site of the first nuclear attack at Hiroshima on Aug 6, 1945, a cenotaph bears the inscription "Rest in peace, for this mistake will not be repeated". While the nature of that mistake has been endlessly debated, for many of those who built the first atomic bombs it was the obscenity of so much intellectual effort being applied to so dreadful a goal.
But while the ends may be forever controversial, the means hold a message for a world fearing global catastrophe from climate change: if we are serious about dealing with the threat, we have to go on a war footing. The idea of declaring a "war on climate change" is gaining ground in environmental circles - and not just as a means of ratcheting up the rhetoric. History makes plain that we are capable of overcoming colossal technical challenges when our survival is at stake.
Set aside for a moment its dreadful end-product and consider the example of the Manhattan Project, begun by the United States in 1942 to create the first atomic bomb. Scientists had estimated that several tens of kilograms of "fissile" material like plutonium would be needed for such a bomb - yet they had succeeded in creating just a millionth of a gram of such stuff. Within three years, production had been boosted by a factor of 10 billion, creating enough fissile material for several bombs.
One obvious lesson is that such projects need huge amounts of manpower and money to succeed. The Manhattan Project had plenty of both: at its height, it involved around 200,000 people - including a dozen current or future Nobel Prize winners - and cost around US$2 billion, equivalent to well over 10 times that amount today. Although manpower and money are critical in projects of such technological complexity, they are far from guarantees of success.
Those attempting to combat climate change face the same challenge that confronted the managers of the Manhattan Project: uncertainty about the effectiveness of any given approach, but the certainty of dire consequences if none succeeds. In the case of the Manhattan Project, the greatest uncertainty surrounded the techniques for making the fissile material needed for the explosive. This led the managers to hedge their bets by working on two different types of atomic bomb and using six different methods to produce the explosive.
Many environmentalists have recognised the need for a similarly diverse approach to cleaner forms of energy. Instead of insisting that renewables like wind-power are the sole way forward, they accept that nuclear power may also have to be part of the mix. It is, however, far less clear that scientists themselves have sufficiently diversified their attempts to develop the ultimate source of clean power: nuclear fusion.