* Best estimate of temperature 0.57 degrees above average
* 2010 is currently warmest year on record
By Nina Chestney
LONDON, Dec 20 (Reuters) - Global temperatures are forecast to be 0.57 degrees above the long-term average next year, making 2013 one of the warmest years on record, Britain's Met Office said on Thursday.
"It is very likely that 2013 will be one of the warmest 10 years in the record which goes back to 1850, and it is likely to be warmer than 2012," the Met Office said in its annual forecast for the coming year.
Next year was expected to be between 0.43 and 0.71 degrees Celsius warmer than the long-term global average of 14 degrees (1961-1990), with a best estimate of around 0.57, it said.
Its forecast is based on its own research as well as data from the University of East Anglia, the NASA Goddard Institute of Space Studies and the U.S. National Oceanic and Atmospheric Administration.
Rising temperatures could be due to the natural variability of the climate and global warming from increasing greenhouse gas emissions, Dave Britton, Met Office forecaster, told Reuters.
A warmer global average temperature does not necessarily mean every region of the world will get hotter, as regional climate variability produces different effects in different parts of the world, he added.
Eleven of the 12 hottest years on record have occurred since 2001, according to data from the World Meteorological Organisation.
Last year is ranked the warmest on record, having been 0.54 degrees above the long-term average, while 2012 is ranked the ninth warmest, with a rise of 0.45 degree Celsius.
Many scientists blame increasing temperatures on man-made greenhouse gas emissions from burning fossil fuels and say they can lead to rising sea levels and extreme weather events.
Global carbon dioxide emissions hit a record high in 2011, led by China, the International Energy Agency said in May.
This year has already seen several examples of extreme weather events, such as superstorm Sandy which hit the east coast of the United States in October. Parts of the United States also experienced their worst drought in more than half a century this summer.
Britain had been suffering a drought before a record wet spring and early summer.
Last week, a leaked draft report from the Intergovernmental Panel on Climate Change showed global average temperatures could be more than 2 degrees above average by 2100 and may reach 4.8 degrees.
Low-lying island states and other countries vulnerable to rising sea levels, floods and hurricanes have been putting pressure on developed countries to curb greenhouse gas emissions and keep the rise in temperatures to within a limit of 2 degrees this century.
A U.N. conference aimed at curbing emissions ended this month with little progress.