When scientists mix with politicians they can go a bit mad. Power brings out the silly side of them. I met a chief scientific adviser once and marvelled at his unscientific certainties, his playing of the man and not the ball, his professional paranoia, his quite astonishing rudeness. And I speak as an expert.

Sir David King is now been made a Climate Ambassador by William Hague. What could go wrong? The first Climate War with China? An ice age?

In front of the Science Committee this morning, a new chief scientific adviser, Sir Mark Walport to talk about communicating climate change.

To play the man for a moment (the ball won’t have much to do with climate change either): He looks like a fatter Basil Fawlty and radiates the same mix of faulty certainty and self-absorption. He might close his eyes when he speaks, and can finish an answer looking straight ahead like the set-up for a piece of slapstick.

What did he say?

He was asked why public belief in climate change had diminished from the 90 per cents to the low 70s.

He put up two possibilities. First: Economic hard times with the associated higher fuel bills. And second: Loud sceptical – though wrong – voices which were being given publicity.

The fact that there has been no warming for 15 years he didn’t mention. But that is the largest, the most obvious, the most brightly-coloured, 96-point, neon-lit reason for the decline in public belief in climate change. The Chief Scientific Adviser was more than capable of ignoring it.

And this is where he displayed the tender innocence of the public scientist. He’s in politics without realising it. Acting like an advocate. Selecting evidence. Making wild assertions. Failing to realise how fragile, how comic his expert certainties look when probed even a little.

Jim Dowd brought him up short, as with an umbrella crook round the throat. Sir Mark had been running a line that he likes about man-made warming, “This is not a matter of opinion or belief. There is a correct answer to this question.” And later, “This is not a matter where sceptical voices might be right.”

Whether or not his beliefs are correct this is a very offensive way of talking.

But Jim Dowd agreed, apparently.”Science is not a democracy,” he said. “There are facts. The fact that 90 per cent of people believe something to be true does not make it true.

Sir Mark: (crisply). Correct!

Dowd: So you cannot simply discount the other 10 per cent because the happen to be the minority.

Sir Mark: (Urgently). Ohhh! Hang on! (Back-pedalling) That’s the sort of argument of the scientific outsider. (Ground softening beneath his feet). There comes a point when the overwhelming consensus is such that (Hang on yourself, so it IS a democracy?) we can be as confident as we can be that the science is correct.

The technical term for that is “bluster”.

I invite to turn over in your mind, ladies and gentlemen of the jury, the phrase “we can be as confident as we can be” and compare it with the claim “there is a correct answer to this”.

“The climate forecast is the weather forecast over a very long period of time,” Sir Mark said towards the end of his session.

That too was unfortunate. Weather forecast accuracy drops like a stone after three days. The forecast for thirty, three hundred, three thousand years time has a reliability of zero.

He realised he shouldn’t have said it. “Perhaps that’s not quite right, maybe not specifically right …” he bloffled (new portmanteau word of uncertain origin).

Given a little poke, these people produce bloffal uncontrollably. They’d make – they do make – lousy politicians. But they’ve been infected by politics and may not even be recognisable as scientists any more.