Climate change has accelerated in the past decade, the UN weather agency releasing data showing that 2001 to 2010 was the warmest decade on record.
The 10-year period was also marked by extreme levels of rain or snowfall, leading to significant flooding on all continents, while droughts affected parts of East Africa and North America.
"The decade 2001-2010 was the warmest since records began in 1850, with global land and sea surface temperatures estimated at 0.46 degrees Celsius above the long term average of 14.0 degrees Celsius (57.2 degrees Fahrenheit)," said the World Meteorological Organisation.
Nine of the 10 years also counted among the 10 warmest on record, it added, noting that "climate change accelerated" during the first decade of the 21st century.
The trend continued in 2011, which was the warmest year on record despite La Nina -- a weather pattern which has a cooling effect.
'The average temperature in 2011 was 0.40 degrees Celsius above the long term average, said the WMO.
"This 2011 annual assessment confirms the findings of the previous WMO annual statements that climate change is happening now and is not some distant future threat," said WMO Secretary-General Michel Jarraud.
"The world is warming because of human activities and this is resulting in far-reaching and potentially irreversible impacts on our Earth, atmosphere and oceans," he added.
The UN weather agency noted that during the decade, "numerous weather and climate extremes affected almost every part of the globe with flooding, droughts, cyclones, heat waves and cold waves."
Historical floods hit Eastern Europe in 2001 and 2005, Africa in 2008, Asia and Australia in 2010.Global precipitation -- including rain or snow -- reached the second highest average since 1901. The highest average was recorded for the decade 1951-1960.
Meanwhile for the North Atlantic basin, the 10 years marked the highest level of tropical cyclone activity, including Hurricane Katrina which struck the United States in 2005 and Cyclone Nargis which hit Myanmar in 2008.
