The number of British people who are sceptical about climate change is rising, a poll for BBC News suggests.
The Populus poll of 1,001 adults found 25% did not think global warming was happening, an increase of 10% since a similar poll was conducted in November.
The percentage of respondents who said climate change was a reality had fallen from 83% in November to 75% this month.
And only 26% of those asked believed climate change was happening and "now established as largely man-made".
The findings are based on interviews carried out on 3-4 February.
In November 2009, a similar poll by Populus - commissioned by the Times newspaper - showed that 41% agreed that climate change was happening and it was largely the result of human activities.
"It is very unusual indeed to see such a dramatic shift in opinion in such a short period," Populus managing director Michael Simmonds told BBC News.