Weather warning

The past decade has been the hottest on record, according to a report released on the sidelines of climate talks taking place this week in Durban, South Africa.

The World Meteorological Organization (WMO), the UN's weather agency, blamed rising levels of carbon dioxide in the atmosphere for a trend which has seen 13 of the 15 warmest years on record occur since 1997.

"Concentrations of greenhouse gasses in the atmosphere have reached new highs," said WMO Secretary General Michel Jarraud in a statement.

"Our science is solid and it proves unequivocally that the world is warming and this warming is due to human activities."

Recent data

The WMO said 2011 would likely end as the 10th warmest year since record-keeping began in 1850.

2011 was influenced by an especially strong La Nina event, a phenomenon driven by cooler than average sea temperatures in the Pacific and frequently tied to extreme conditions in Asia, Africa and South America.

A La Nina – the opposite of an El Nino event – tends to have a cooling effect on average global temperatures. The WMO said 2011 was the hottest year in which a La Nina occurred.

This year's La Nina was linked to flooding in Thailand as well as drought in eastern Africa and the southern United States.

Elsewhere, the WMO said Arctic sea ice shrunk to its lowest volume on record this year– some 4,200 cubic kilometers.

By surface area, the region's sea ice dropped about 35 percent below the 1979-2000 average to arrive at its second-lowest point. The record-low was set in 2007.

Russia experienced some of the greatest temperature variation this year, with thermometers reaching up to four degrees Celsius above average in certain areas, the WMO said.

Delegates warned

The report's publication – on the second day of two weeks of talks aimed at finding a compromise to tackle climate change – was timed to motivate policymakers to action.

"A sense of urgency is required in taking in this information," Jerry Lengoasa, WMO Deputy Secretary General, told reporters on the sidelines of the talks.

In a statement, Secretary General Jarraud said the goal to limit climate change to below two degrees of warming this century was in jeopardy due to current levels of carbon emissions.

"They are very rapidly approaching levels consistent with a 2-2.4 degree Centigrade rise in average global temperatures which scientists believe could trigger far reaching and irreversible changes in our Earth, biosphere and oceans," he said.

In a separate report earlier this month, the WMO said concentrations of the main greenhouse gasses blamed for climate change were growing more rapidly than during the 1990s.

The organization said carbon dioxide rose by 2.3 parts per million (ppm) in the space of a year to reach 389 ppm in 2010. That compares to an annual average rise of 1.5 ppm during the 1990s.

Scientists say the concentration of carbon dioxide in the atmosphere needs to be stabilized at 450 ppm to have a good chance of limiting warming to below two degrees.

Author: Nathan Witkop (Reuters, dpa, AFP)
Editor: Cyrus Farivar