An apparent cooling trend is exaggerated by a record high temperature in 1998 caused by El Niño, experts say
- Monday September 22 2008 17:40 BST
Climate sceptics such as Nigel Lawson who argue that global warming has stopped have their "heads in the sand", according to the UK's Met Office.
A recent dip in global temperatures is down to natural changes in weather systems, a new analysis shows, and does not alter the long-term warming trend.
The office says average temperatures have continued their rising trend over the last decade, and that humans are to blame.
In a statement published on its website, it says: "Anyone who thinks global warming has stopped has their head in the sand.
"The evidence is clear, the long-term trend in global temperatures is rising, and humans are largely responsible for this rise. Global warming does not mean that each year will be warmer than the last."
The new research confirms that the world has cooled slightly since 2005, but says this is down to a weather phenomena called La Niña, when cold water rises to the surface of the Pacific Ocean. Despite this effect, the office says, 11 of the last 13 years are the warmest ever recorded.
Vicky Pope of the Met Office said the new research was in response to high-profile claims made by Lawson the former chancellor, and others that the recent cooling showed that fears of climate change are overblown, and that temperatures are unlikely to rise as high as predicted.
She said: "I think it has confused people. We got a lot of emails asking whether global warming had stopped and it prompted us to look at the data again and try and understand the situation better."
The apparent cooling trend is exaggerated by a record high temperature in 1998 caused by a separate weather event, El Niño, she said. "You could look at what happened in 1998 and say that global warming accelerated and that's not true either.
"Any statistician will tell you that you can't just draw a straight line between two points, you need to look at the underlying trend."
Despite the recent cooling, average temperatures are still rising at 0.09C per decade, the office says - down from the record 0.33C per decade measured during the 1990s.