Carbon dioxide in the atmosphere is a natural phenomenon caused by volcanoes and is not responsible for climate change, a scientist has claimed.
Professor Ian Plimer, a geologist from Adelaide University, argues that a recent rise in temperature around the world is caused by solar cycles and other "extra terrestrial" forces.
He said carbon dioxide in the atmosphere, widely blamed for global warming, is a natural phenomenon caused by volcanoes erupting.
"We cannot stop carbon emissions because most of them come from volcanoes," he said. "It is a normal element cycled around in the earth and my science, which is looking back in time, is saying we have had a planet that has been a green, warm wet planet 80 per cent of the time. We have had huge climate change in the past and to think the very slight variations we measure today are the result of our life - we really have to put ice blocks in our drinks."
Most mainstream scientists agree that the recent warming period was caused by an increase in carbon dioxide since the industrial revolution.
However Prof Plimer said the world has experienced three periods of cooling since 1850 and furthermore carbon dioxide was increasing during many of those cooler periods.
"If we had only had warming, then there would be a connect between co2 and temperature, there is not," he added.
Prof Plimer has come under attack as a "denialist poster boy" whose theories are in danger of stopping the world from tackling the grave dangers of climate change.
But he said the scientists "frightening people witless by following the party line" are motivated by politics and research funding.
"They are taking advantage of the current situation. That is understandable. In previous times people got wonderful research grants in a war against cancer and they achieved a lot of money for that. Now we have a war on climate change and we have a huge number of people out there who have their career staked on it and are beneficiaries of this process."
Vicky Pope, Head of Climate Change Advice at the Met Office, said it is widely accepted that carbon dioxide in the atmosphere has doubled in the last 200 years and as a result the globe is warming.
She said there are "natural variations" in temperature caused by the weather as well as natural phenomenon like El Nino and human effects like pollution, but overall the climate has been getting hotter and has reached its warmest period in recent years.
"The basic physics is that if carbon dioxide increases then the temperature goes up," she said.
A number of "climate change sceptics" will be giving talks in the run up to a key UN Summit in Copenhagen in December when the world is expected to agree an international deal to stop global warming.