Global warming is caused by radiation from the sun, according to a leading scientist speaking out at an alternative "sceptics' conference" in Copenhagen.
As the world gathered in the Danish capital for the UN Climate Change Conference, more than 50 scientists, businessmen and lobby groups met to discuss the arguments against man made global warming.
Although the meeting was considerably smaller than the official gathering of 15,000 people meeting down the road, the organizers claimed it could change the course of negotiations.
Professor Henrik Svensmark, a physicist at the Danish National Space Center in Copenhagen, said the recent warming period was caused by solar activity.
He said the last time the world experienced such high temperatures, during the medieval warming period, the Sun and the Earth were in a similar cycle.