The Stern report into climate change is based on "implausible" economic and scientific assumptions, former Chancellor Lord Lawson has told MPs.
Lord Lawson says money should not be spent 'foolishly'
Lord Lawson said the report was a "biased" attempt to please ministers rather than an "objective" study.
And money would be better spent on dealing with the effects of climate change rather than trying to halt it.
Sir Nicholas Stern described Lord Lawson's criticisms of his work as "name-calling without substance".
Sir Nicholas, a former World Bank economist, said in his government-sponsored report it would cost 1% of annual global GDP to stabilise greenhouse gas emissions.
But the cost of doing nothing now would cause a 5% to 20% loss in GDP.
Lord Lawson told the Commons Treasury committee he believed the scientific assumptions behind Sir Nicholas's report were imprecise.
He accepted it was "highly likely" man-made carbon emissions had contributed to temperatures increasing 0.7C during the 20th century.
"It has played a part, but we don't know how big a part," the Conservative peer told MPs.
Some climate scientists were predicting "another ice age" in the next 100 years, Lord Lawson added, but even if temperatures were going up there was little mankind could do about it.
It would make more sense to "monitor" any changes and deal with any harmful consequences "rather than attempt at huge cost to cut back drastically, as the Stern report recommends, on carbon dioxide emmissions".
Lord Lawson told MPs: "One of the oddities of this whole field is that you apply weather forecasting to economic forecasting to demographic forecasting, you pile uncertainty on uncertainty and then apparently you come to a certain conclusion of what we should do.
"I think that is highly implausible to anybody that stops to think about it."
Even under the worst case scenario set out by Stern, future generations would only be slightly worse off financially as a result of global warming, Lord Lawson said.
"The proposition is that we should ask the people of this generation [to] make considerable sacrifices now so that their grandchildren, their great grandchildren, are seven times as well off as they are today, rather than only six times as well off."
He accused Sir Nicholas of being unduly influenced by the government's environmental policy.
"The Stern report has turned out basically to be a work of advocacy... but I think a more objective, analytical approach would have been more helpful.
"He [Stern] ramps up the alleged costs of warming to an inordinate degree and the benefits of warming are scarecely mentioned.
"The costs of mitigation are, in my view, grossly understated and the whole thing is very biased."
Lord Lawson said Britain would see "great benefits" from climate change over the next 100 years.
And investing in new technology - and building better flood defences - would be a "quicker and easier" way to deal with rising temparatures than cutting emissions.
"We should be careful about future threats but we should be careful not to spend money foolishly," he told the committee.
Sir Nicholas, appearing earlier before the same committee, described Lord Lawson's criticisms of his work as "name- calling without substance," adding he could refute each of Lord Lawson's points.
Asked about the peer's description of carbon trading schemes as "capricious and corrupt," he said: "It is not a very analytical use of language and I don't think it bears scrutiny frankly.
"The emissions trading scheme works in the EU, if you think of it in terms of a two year history".