The United Nations' weather agencysays 2010 was one of the warmest yearson record,
providing further evidence thatthe planet is slowly but surely heating

(无法处理)up.
     The World Meteorological Organization says globalaverage temperatures last year
were just over half a degreeCelsius higher than the 1961~1990 period, slightly abovethe
temperature of 2005, and a little higher again over thatof 1998, which were previously
two of the top threewarmest years on record.
     Michel Jarraud, an official in the World MeteorologicalOrganization, said, "We can
indeed report that 2010 is nowgoing to rank as the warmest year on record at the same
level as 2005 and 1998. "
     The ten warmest years after records began in 1854 haveall occurred since 1998. Rising
global temperatures over the last century arecausing climate experts to worry.
     The Geneva-based global weather agency says that lastyear's extreme weather-notably
the heat wave in Russiaand monsoon(季风,雨季)flooding in Pakistan--hascontinued into
the new year.
      Michel Jarraud also said, "What we can say is that withglobal warming some of these
events will become morefrequent or more intense. "
     The UN agency contributes the extreme weatherpatterns to El Nino and La Nina,
which constantlydominated the world climate in 2010, bringing warm effectsand cooling
effects respectively.
     Apart from extreme weather conditions, the WM() alsonoticed further melting of Arctic
sea-ice.ln December 2010,ice cover around the region registered its lowest level, 1. 35million
square kilometers below the 1979-2000 Decemberaverage.

     A nearly ice-free Arctic Ocean inthe summer may happen three timessooner than scientists
have assessed.New research says the Arctic might lose

most of its ice cover in summer in as few as 30 years insteadof by the end of the century.
     The amount of the Arctic Ocean covered by ice at theend of summer by then could be
only about 1 million squarekilometers. That's compared to today's ice extent c范围)of4. 6
million square kilometers. So much more open watercould be an advantage for shipping
and for extracting(开采)minerals and oil from the seabed, but it raises the questionof
ecosystem change.
     While the Intergovernmental Panel on Climate Change in 2007 assessed what might
happen in the Arctic in the future based on results from more than a dozen globalclimate
models, two researchers said that the dram4tic dropsin the extent of ice at the end of
summer in 2007 and 2008called for a different approach.     
     Out of the 23 models now available, the newpredictions are based on the six most
suited for assessing sea ice, according to Muyin Wang, a climate scientist in a university
of Washington, and James Overland, an oceanographer. Wang and Overland sought
models that best matched what has actually happened in recent years,because, "if a
model can't do today's conditions well, howcan you trust its future predictions?" Wang
says. "
     In recent years the combination of unusual warmtemperatures from natural causes
and the global warmingsignal have worked together to provide an earlier summersea-ice
loss than was predicted when scientists consideredthe effects from human-caused

carbon dioxide alone," saysOverland.
     Scientists don't expect the Arctic to be totally ice free,figuring that ice still will be
found along northern Canadaand Greenland where powerful winds sweeping across
theArctic Ocean force ice layers to slide on top of each other,making for a very thick
ice cover.