“The decade 2000-2009 is very likely to be the warmest on record, warmer than the 1990s, which were in turn warmer than the 1980s,” WMO Secretary-General Michel Jarraud said at a press conference.
Jarraud also said that the year 2009 would probably rank as the fifth warmest since the beginning of accurate instrumental climate records in 1850.
Meanwhile, Britain released data from hundreds of monitoring stations worldwide showing that the global surface temperature has risen significantly over the past 150 years.
The statistics are being made public as countries from around the world are locked in UN climate change talks in Copenhagen which could lead to a new deal to cut emissions blamed for global warming.
Perhaps the most striking finding is that the rise in global surface temperature has averaged more than 0.15 degrees Celsius per decade since the middle of the 1970s.
Britain’s Met Office released millions of records from over 1,500 of 5,000 stations worldwide which monitor land surface temperatures.
The records, which it has only just received permission to release, date back to 1850 and the Met Office eventually hopes to publish all 5,000.
“Global average temperature has increased over the past century and this warming has been particularly rapid since the 1970s,” said the Met Office climate scientist Peter Stott, commenting on the findings.
The data is a subset of the so-called HadCRUT record which is used by top UN body the Intergovernmental Panel on Climate Change (IPCC).
The Met Office works alongside two centres in the US to calculate monthly global temperature averages — the Goddard Institute for Space Studies, which is part of NASA, and the National Climatic Data Center.
It also collaborates with the Climate Research Unit at Britain’s University of East Anglia (UEA), recently embroiled in a controversy over hacked emails on climate change. Its head Professor Phil Jones stood aside after emails allegedly calling into question the scientific basis for climate change fears were posted online.
Hackers penetrated the centre’s network and posted online thousands of emails from researchers, including Jones. In one private email, Jones referred to a “trick” being employed to massage temperature statistics to “hide the decline”.
The academic said they had been taken out of context.