Lord Christopher Monckton and Dr Richard Denniss address National Press Club.

Lord Christopher Monckton greets Dr Richard Denniss at the National Press Club debate.

TOURING British climate change sceptic Lord Christopher Monckton today told Tony Abbott to drop his Direct Action plan to cut carbon emissions.

"The Coalition should in my opinion ditch it because there is no need to take any action about carbon dioxide at all," Lord Monckton told the National Press Club during a good-natured debate.

But he saved his sharpest advice for Prime Minister Julia Gillard's Government, claiming that Australia overseas was now considered a sovereign risk - that it would default on its debts.

Lord Monckton believes the globe is warming but strongly disbelieves that human-produced carbon emissions are significantly adding to the warming rate.

"The people of Australia are frightened. They are frightened of their Government, they are frightened of you," he told journalists at the NPC where he debated economist Dr Richard Denniss.

"The world is also frightened. Australia is now regarded as a sovereign risk."

The claim, which appeared to rank Australia with the problem economies of Greece and Ireland, ignored the huge rate of foreign investment here and our high credit rating.

But Lord Monckton insisted his argument against climate change measures was correct, as was his right to claim to be a member of the House of Lords.

He was bitter about a July 15 letter from the Clerk of the Parliaments in Westminster, London, advising Viscount Monckton of Brenchley he should "cease claiming to be a member of the House of Lords".

The snubbed peer shot back yesterday: "The House of Lords says I'm not a member of it. My passport says I am. Get used to it."

He said the letter was impertinent: "And they should put my reply on their website. They have not so far found the courage to answer."

Dr Denniss agreed with him that Tony Abbott should drop his Direct Action plan, because it would cost too much.

"If you are genuinely worried about the cost of tackling climate change then every economist is of the view ... again, Tony Abbott can't find a single economist to agree with him that his scheme is cheaper," he said.

"If you believe climate change is bunkum ... why aren't climate change sceptics economic sceptics as well?

Lord Monckton shared his fondness for the gas which the Government wants reduced, saying that on any view, carbon dioxide was not a pollutant but would help produce better food crops.

"It is plant and tree food," he said to instant applause from a large group of supporters at the NPC.

"If we were able to manage a doubling of CO2 concentration this century, which is what I expect to happen regardless of the carbon tax, then what we would find is that at the end of the century the yield of certain staple crops would rise by up to 40 per cent.

"And they would be able to survive on less water as well.

"The greening of the planet in the 30 years since satellites have been watching, as a result of what is known as CO2 fertilisation is absolutely wonderful."