The number of British people who are skeptical about climate change is rising, a poll for BBC News has suggested.
According to BBC News, the findings are based on interviews carried out on 3 - 4 February.
The Populus poll of 1,001 adults found that 25 percent did not think global warming was happening, a rise of 8 percent since a similar poll was conducted in November.
The percentage of respondents who said climate change was a reality had fallen from 83 percent in November to 75 percent this month.
Only 26 percent of those asked believed climate change was happening and "now established as largely man-made".
Of the 75 percent of respondents who agreed that climate change was happening, one-in-three people felt that the potential consequences of living in a warming world had been exaggerated, up from one-in-five people in November.
The number of people who felt the risks of climate change had been understated dropped from 38 percent in November to 25 percent in the latest poll.
In November 2009, a similar poll by Populus showed that 41 percent 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.
"The British public are sceptical about man's contribution to climate change - and becoming more so," he added.
"More people are now doubters than firm believers," he said.
According to Professor Bob Watson, the Department for Environment, Food and Rural Affairs' chief scientific adviser, the findings are "very disappointing".
"The fact that there has been a very significant drop in the number of people that believe that we humans are changing the Earth's climate is serious," he told BBC News.
"Action is urgently needed," Professor Watson warned.
"We need the public to understand that climate change is serious so they will change their habits and help us move towards a low carbon economy," he said.