Climate change sceptic Christopher Monckton says he was catastrophically stupid to compare the prominent Australian economist Ross Garnaut to Adolf Hitler.

In a speech in Los Angeles, Lord Monckton displayed a quote from the Federal Government's chief climate change adviser, Professor Garnaut, next to a Nazi swastika.

Lord Monckton called Professor Garnaut a fascist for suggesting people accept climate science.

But Lord Monckton has now told Channel Ten that he has apologised.

"First of all I should apologise on air once again to Professor Garnaut for having made the point I was trying to make in such a catastrophically stupid and offensive way," he said.

"I have written to him to withdraw that unreservedly."

Lord Monckton is known around the world for his argument that humans are not damaging the climate.

In the Channel Ten interview, Lord Monckton insisted the planet was not warming as fast as scientists claim. He says if it is, the best response is to adapt.

"Even if it were as much as they say, the fact is that economically speaking, it's better to let it happen and adapt to any consequences that may occur, in a focused way, if and only where and only when and only to the extent that they occur," he said.

"That's the economically responsible way forward."

The British peer is scheduled to speak at the Association of Mining and Exploration Companies (AMEC) conference in Perth this week.

Federal Opposition Leader Tony Abbott is also speaking at the AMEC conference but says he has no plans to meet Lord Monckton.

Last week Mr Abbott moved to distance himself from the controversial comments.

"I thought that those comments were offensive and over the top and I repudiate them," he said.

Prime Minister Julia Gillard described Lord Monckton's actions as "very offensive and grossly unacceptable".