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The year 2011 caps a decade that ties the record as the hottest ever measured, the WMO said in a provisional report on climate trends and extreme weather events, unveiled at UN climate talks in Durban.
“Our science is solid and it proves unequivocally that the world is warming and that this warming is due to human activities,” WMO SecretaryGeneral Michel Jarraud said in a statement, adding that policy makers should take note of the findings.

“Concentrations of greenhouse gases in the atmosphere have reached new highs and are very rapidly approaching levels consistent with a 2 to 2.4 Celsius rise in average global temperatures.”
Scientists believe that any rise above the 2.0 threshold could trigger farreaching and irreversible changes over land and in the seas.

The 20022011 period equals 20012010 as the warmest decade since 1850, the report said.
2011 ranks as the 10th warmest year since 1850, when accurate measurements began.

This was true despite a cooling La Nina event  one of the strongest in 60 years  that developed in the tropical Pacific in the second half of 2010 and continued until May 2011.
The report noted that the cyclical climate phenomenon, which strikes every three to seven years, helped drive extreme weather events including drought in east Africa, islands in the equatorial Pacific and the southern United States.

While La Nina, and its meteorological cousin El Nino, are not caused by climate change, rising ocean temperatures caused by global warming may affect their intensity and frequency, scientists say.
Average surface temperatures over land were above longterm averages in most regions.

“There is no single country that has reported 20012010 mean temperatures that are colder than their national longterm average from 19611990,” WMO Deputy Secretary General R.D.J. Lengoasa told journalists in Durban, citing a forthcoming review of weather trends over the last ten years.

For 95 percent of 80 countries that had submitted relevant data, 20012010 was the warmest decade on record, he added.
Forty percent had seen national heat records broken in 20012010, as compared to 15 percent in the 19912000 period, and 10 percent in the 19811990 period. — Sapa.