Global warming is now advancing so swiftly that only a massive expansion of nuclear power as the world's main energy source can prevent it overwhelming civilisation, the scientist and celebrated Green guru, James Lovelock, says.
His call will cause huge disquiet for the environmental movement. It has long considered the 84-year-old radical thinker among its greatest heroes, and sees climate change as the most important issue facing the world, but it has always regarded opposition to nuclear power as an article of faith. Last night the leaders of both Greenpeace and Friends of the Earth rejected his call.
Professor Lovelock, who achieved international fame as the author of the Gaia hypothesis, the theory that the Earth keeps itself fit for life by the actions of living things themselves, was among the first researchers to sound the alarm about the threat from the greenhouse effect.
He was in a select group of scientists who gave an initial briefing on climate change to Margaret Thatcher's Conservative Cabinet at 10 Downing Street in April 1989.
He now believes recent climatic events have shown the warming of the atmosphere is proceeding even more rapidly than the scientists of the UN's Intergovernmental Panel on Climate Change (IPCC) thought it would, in their last report in 2001.
On that basis, he says, there is simply not enough time for renewable energy, such as wind, wave and solar power - the favoured solution of the Green movement - to take the place of the coal, gas and oil-fired power stations whose waste gas, carbon dioxide (CO2), is causing the atmosphere to warm.
He believes only a massive expansion of nuclear power, which produces almost no CO2, can now check a runaway warming which would raise sea levels disastrously around the world, cause climatic turbulence and make agriculture unviable over large areas. He says fears about the safety of nuclear energy are irrational and exaggerated, and urges the Green movement to drop its opposition.
In today's Independent, Professor Lovelock says he is concerned by two climatic events in particular: the melting of the Greenland ice sheet, which will raise global sea levels significantly, and the episode of extreme heat in western central Europe last August, accepted by many scientists as unprecedented and a direct result of global warming.
These are ominous warning signs, he says, that climate change is speeding, but many people are still in ignorance of this. Important among the reasons is "the denial of climate change in the US, where governments have failed to give their climate scientists the support they needed".
He compares the situation to that in Europe in 1938, with the Second World War looming, and nobody knowing what to do. The attachment of the Greens to renewables is "well-intentioned but misguided", he says, like the Left's 1938 attachment to disarmament when he too was a left-winger.
He writes today: "I am a Green, and I entreat my friends in the movement to drop their wrongheaded objection to nuclear energy."
His appeal, which in effect is asking the Greens to make a bargain with the devil, is likely to fall on deaf ears, at least at present.
"Lovelock is right to demand a drastic response to climate change," Stephen Tindale, executive director of Greenpeace UK, said last night. "He's right to question previous assumptions.
"But he's wrong to think nuclear power is any part of the answer. Nuclear creates enormous problems, waste we don't know what to do with; radioactive emissions; unavoidable risk of accident and terrorist attack."
Tony Juniper, director of Friends of the Earth, said: "Climate change and radioactive waste both pose deadly long-term threats, and we have a moral duty to minimise the effects of both, not to choose between them."