Former chancellor Lord Lawson has downplayed the threat of climate change and attacked attempts to deal with it.
Speaking at a House Magazine debate in Westminster on Monday, the Conservative peer said green taxes would have to be so high to change people's behaviour that the public would not accept them.
Lord Lawson was debating with Liberal Democrat Treasury spokesman Julia Goldsworthy, whose party proposes radical hikes in environmental levies on airlines and cars.
He said such measures were premature as there is still no concrete evidence that the Earth is warming up as a result of carbon emissions.
He highlighted an unreported annexe to the Treasury's recent Stern report on the economics of climate change as admitting that the report was simply a "contribution to the discussion" on global warming.
And he argued that the science contained within the Stern findings had been "completely misrepresented in most of the media".
The peer acknowledged that global warming is taking place but said carbon emissions may not be "the main reason for this". Instead he suggested that natural causes could be just as likely to be the driving force.
Lord Lawson said the "market will deal" with any problems that carbon emissions are creating.
"The alternative is mind-bogglingly complicated," he argued, pointing to the difficulties in persuading emerging economies such as China and India to curb their growth.
He said western countries would have to cut their emissions by an even greater amount to compensate, creating severe problems for their own economies.
The peer said, even if the Stern report's calculations as correct, living standards are projected to be seven times higher in 100 years time than they are now.
And assuming there are no technological innovations in tackling carbon emissions, global GDP would be hit by 20 per cent in the same period as a result of climate change.
But he said that would mean even with climate change the world would still "only be a little less than six times" as well off as they are now.
In such circumstances he said it would be "difficult to persuade people to make huge sacrifices" to their lifestyles.
However he added that "does not mean I am against green taxes".
Lord Lawson argued that the alternative of emissions trading schemes was like "allowing people to sell tobacco rations".
"If people are prepared to pay carbon tax, providing that the revenues are used to reduce other taxes, I have no objection to that," he said.
But he said that "level would need to be too high for people to accept" in order to make a meaningful difference.
Goldsworthy
In response Lib Dem MP Goldsworthy said "there is a scientific consensus" that global warming is caused by carbon emissions.
And she argued that whatever its cause, effects such as flooding, should not be underestimated.
Goldsworthy said green taxes were needed as one of a "whole range of measures" to change behaviour.
The frontbench spokesman said investment in renewable energy, regulations such as the recent Australian ban on non-efficient light bulbs and voluntary measures were all required.
She agreed that it is "better to work with market forces" where possible.
But she added that carbon trading should not be discounted.
"The EU carbon trading scheme hadn't been a fundamental success as they issued more permits than there were emissions," she accepted.
However she said despite this flaw it had still "helped bring down emissions".
While the scheme could be improved, she said policy-makers should "not throw the baby out with the bathwater".
On green taxes, Goldsworthy said the "key thing is to tackle aviation".
She said the government's recent doubling of air passenger duty had been a "token gesture" that "is not going to affect behaviour".
Taxes should be steeper, she argued, and levied on whole flights rather than individual passengers so as to incentivise efficient travel through full planes.
She also warned supporters of environmental taxes that they must ensure poor people do not pay more and have the option to choose green forms of travel and energy.
