Details presented to the United Nations climate change conference in Copenhagen show the current decade is the warmest on record.
The World Meteorological Organisation says 2009 is set to be the fifth warmest year since records began in 1850.
The agency says there's no doubt that the world is in a warming trend.
Secretary-general Michel Jarraud said climate extremes, including devastating floods, severe droughts, snowstorms, heatwaves and cold snaps, were registered in many parts of the world.
Above-normal temperatures were recorded in all continents except North America.
The WMO uses three temperature sets - one from the UK Met Office and the University of East Anglia's Climatic Research Unit - and two from the US, maintained by the National Oceanic & Atmospheric Administration and the space agency NASA.
The two-week conference is in its second day.
