The past 10 years have been the warmest decade on record and this year has been one of the five hottest, scientists revealed today as negotiators attempt to make progress on a new international deal to combat climate change.
While 1998 remains the hottest single year since records began, the past decade has been the warmest period in the 160-year record of global surface temperatures, the Met Office announced.
And 2009 is another of the warmest years, according to the UN's weather experts the World Meteorological Organisation (WMO) which published provisional findings that this year was 0.44C above the long term average of 14C.
It is expected to become the fifth warmest year since instrumental records began in 1850, the Met Office said, and will be warmer than 2008 because of the emergence of El Nino weather patterns in the Pacific Ocean which contribute to warmer temperatures.
The data from the WMO shows that for large parts of southern Asia and central Africa, it will have been the warmest year on record,
But north America experienced conditions that were cooler than normal - although Canadian cities Vancouver and Victoria saw new record temperatures set and Alaska had the second-warmest July on record.
Extreme climatic events including devastating floods, severe droughts, snowstorms and heat waves were recorded in many parts of the world.
The climate change experts said the results for the decade as a whole highlighted that the world continues to see a trend of global temperature rises, most of which is due to increasing emissions of greenhouse gases.
The global temperature analysis is based on three data sets: one held by the Met Office and the University of East Anglia's Climatic Research Unit, one maintained by Nasa's Goddard Institute and one by the National Oceanic and Atmospheric Administration (NOAA).
Dr Peter Stott, climate scientist at the Met Office, said: "If you average the temperatures up over the whole decade it shows very clearly that this most recent decade is the warmest in the instrumental record."
He said the data showed, even once uncertainties were taken into account, that the 2000s were significantly warmer than the 1990s, which were warmer in turn than the decade before.
The data shows the argument that global warming has stopped is "flawed", researchers said.
Professor Andy Pitman, joint director of the Climate Change Research Centre at the University of New South Wales in Australia, said that low solar activity and the presence of a sustained La Nina weather pattern which contributes cooler temperatures should have meant that 2009 was a cool year.
"The fact it ranked in the top five since 1850 is actually frightening," he said.
Professor Tim Flannery, Professor of Environmental and Life Sciences at Macquarie University, in Sydney, and Chairman of the Copenhagen Climate Council said: "A central plank of the climate sceptics' creed has been that the Earth has been cooling since 1998.
"They have misled many, and damaged public policy as a result. Here is the definitive proof that they are wrong.
"Unfortunately the warming trend continues, and will continue as long as greenhouse gas concentrations continue to grow."
Responding to the figures released at the UN talks in Copenhagen today, Greenpeace climate campaigner Joss Garman said: "This is an unmistakable climate signal that shows how humans are warming the Earth.
"The core of the sceptics' case was that we've been experiencing global cooling, but that claim was never justified by the science."
He added: "This won't stop some people pushing the conspiracy theory that climate change isn't happening, but here in Copenhagen the new data is being discussed by governments and is sure to focus minds."