George says my physics is "bafflingly bad" and contains "downright misrepresentation and pseudo-scientific gibberish". Yet he himself nonsensically refers to "lambda" as a "constant" in the Stefan-Boltzmann radiative-transfer equation. Lambda is not a constant, and it's not a term in the equation.

He wrongly states that the equation only describes "black bodies" that absorb all radiant energy reaching them. No qualified physicist would make such a schoolboy howler. Of course the equation isn't limited to black bodies. Its emissivity variable runs from zero for white bodies to 1 for black bodies. The Earth/troposphere system is a rather badly-behaved grey body with emissivity about 0.6.

He lifted these errors verbatim from a blog run by two authors of a now-discredited UN graph that tried to abolish the medieval warm period. I'd exposed the graph in my articles. Check your sources, George.

He says I was wrong to reinstate the medieval warm period cited by the UN in 1990 but abolished by it in 2001. A growing body of scientific papers, some of which I cited, shows that the warm period was real, global and up to 3C warmer than now. Check them out, George.

He says I shouldn't have said the Viking presence in the middle ages shows Greenland was warmer than now. The Viking farmsteads in Greenland are now under permafrost, and you can't farm permafrost.

He says I was wrong to say James Hansen told Congress in 1988 that world temperature would rise 0.3C by 2000. Hansen projected 0.25 and 0.45C, averaging 0.35C. Outturn was 0.05C. I fairly said 0.3C and 0.1C. He says my source was a work of fiction by Michael Crichton. It wasn't: it was Hansen's graph.

He says I overlooked the difference between the immediate and delayed temperature response to changing conditions. In fact I expressly addressed it, citing evidence on both sides of the theory that the delayed air-temperature response arises from warming of the oceans.

He says I said the warming effects of carbon dioxide had been "made up". I didn't. I said all were agreed that there was more CO2 around and that we could expect some warming. But there is no consensus on how much.

He says I claimed to know better than the UN's scientists. I'm arrogant, George, but not that arrogant: I said the contrarians were probably a lot closer to the truth than the UN.

Too many facts wrong. Too much argument ad hominem instead of ad rem. Too much ignorance of the elementary physics of radiative transfer and equilibrium temperature.

Still, gie the puir numpty a cigar - at least he spelled my name right.

· Viscount Monckton of Brenchley is a former adviser to Margaret Thatcher. bikerbikerbiker@hotmail.com

· The Response column offers those who have been written about in the Guardian an opportunity to reply. If you wish to respond, at greater length than in a letter, to an article in which you have featured either directly or indirectly, please email response@theguardian.com or write to Response, The Guardian, 119 Farringdon Road, London EC1R 3ER. We cannot guarantee to publish all responses, and we reserve the right to edit pieces for both length and content.