The phrase “climate change denier” has a nasty ring to it. It links those who dispute mainstream science on global warming with “Holocaust deniers”. They are not just wrong, it implies, they are evil.

But the climate change lobby is in the grip of its own form of dangerous fantasy. It is in denial not about science – but about international politics.

At the moment, efforts to deal with global warming are focused on a huge international summit in Copenhagen in December. But the chances of Copenhagen delivering a deal that meets the goals for carbon dioxide emissions set by the United Nations Panel on Climate Change is vanishingly small. In private, many climate change activists will admit this. But Copenhagen is the only game in town – so they keep playing.