I like the sound of this NASA scientist Prof Jim Hansen, who intends to use his acceptance speech for a major award on Tuesday to issue a fresh warning about man-made climate change.

It has been mind-boggling to witness the way that climate change denial has become a right-wing political virility symbol, like low taxes, high defence spending or a belief that private is always better than public. The difference with this particular piece of right-wing nonsense is the possible consequences include at best more and more ‘natural’ disasters, folllowed by promises to learn lessons ‘so it never happens again’, followed by not learning lessons so it all happens again, and at worst the end of the planet.

Prof Hansen compares the world’s failure to face up to this now with a previous generation’s acceptance of slavery. We look back now and wonder how people could have treated their fellow human beings so badly. And the science is there to tell us one day future generations will look back at ours – assuming the earth is still with us – and ask why we failed to act when we knew that we should? ‘We can only pretend we don’t know because the science is crystal clear,’ he says.

He intends to set out the facts that show that the current approaches to CO2 reductions aren’t working. indeed, even if the world had delivered on previous agreements like Kyoto -which it hasn’t – he reckons we would still be on the brink of an emergency.

I noticed that among the Tory donors who had been for dinner with David Cameron in Downing Street were funders of climate change denial campaigns. I am not suggesting a direct link, but I do find it odd that Mr Cameron, for whom green credentials were such an important part of the so-called detoxification of the Tory brand, has gone so quiet on the subject. Nor have Chris Huhne when he was Climate Change Secretary, nor Ed Davey now, given any real sense of the urgency required.

One government can only do so much. The kind of challenge set out by Prof Hansen will require all governments to show leadership currently lacking not just in ours, but in most of them. Not long ago, this was one of THE issues dominating the agenda of leaders around the world. It is as though they have just decided the problem is too big to be tackled. Professor Hansen’s speech deserves to be heard by all of them, to remind them of the abdication of responsibility this troubling silence among many world leaders represents.