15 January 2013 Last updated at 16:56 ET
By Matt McGrath Environment correspondent, BBC News
Despite a record hot year in the US, the rest of the world did not follow
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US scientists say that 2012 was among the 10 warmest years the world has experienced since 1880.
Nasa researchers said it was the ninth warmest year while experts from another American agency said it was the 10th.
Both teams said that temperatures would have been higher if it had not been for the La Nina weather pattern that brought cooling to some regions.
They were equally certain carbon dioxide had been the principal driver of the rise over the past 50 years.
The National Oceanic and Atmospheric Administration (Noaa) said that their analysis of temperature data from a global network of weather stations indicated that the average temperature for 2012 was 0.57C above the 20th Century average.
The agency stated that all 12 years of the 21st Century rank among the 14 warmest in the 133-year period of record keeping.
“This past year, unlike the US they were not a record globally but they certainly were warm,” said Thomas Karl, director of Noaa’s National Climatic Data Centre. (more).