GENEVA (Reuters) - Ice volume around the Arctic region hit the lowest level ever recorded this year as climate extremes brought death and devastation to many parts of the world, the U.N. weather agency WMO said on Tuesday.
Although the world's average temperature in 2008 was, at 14.3 degrees Celsius (57.7 degrees Fahrenheit), by a fraction of a degree the coolest so far this century, the direction toward a warmer climate remained steady, it reported.
"What is happening in the Arctic is one of the key indicators of global warming," Michel Jarraud, Secretary General of the World Meteorological Organization (WMO), said. "The overall trend is still upwards."
A report presented by Jarraud at a news conference showed Arctic ice cover dropping to its second lowest extent during this year's melt season since satellite measuring began in 1979.
However, the Geneva-based agency said, "because ice was thinner in 2008, overall ice volume was less than in any other year." It added: "The season strongly reinforced the 30-year downward trend in the extent of Arctic Sea ice."
The dramatic collapse of a quarter of ancient ice shelves on Canada's Ellesmere Island in the north of the Arctic Ocean added to earlier meltdowns, reducing cover in the region from 9,000 square km (3,500 sq miles) a century ago to just 1,000 sq kms.
The WMO said the slight slowdown in warming this year, an increase of 0.31C over the 14C of the base period 1961-90, against an average 0.43C for 2001-2007, was due to a moderate-to-strong La Nina in the Pacific in late 2007.
"This decade is almost 0.2 degrees (Celsius) warmer compared to the previous decade. We have to look at it in that way, comparing decades not years," Peter Stott, a climate scientist at Britain's Hadley Center, which provided data for the WMO report, told Reuters in London.
La Nina is a periodic weather pattern that develops when Pacific sea water cools. It alternates irregularly with the related El Nino -- when the Pacific warms up -- and both affect the climate all round the world.
The WMO report was based on statistics and analyses compiled by weather services among its 188 member countries and specialist research institutions, including government-backed bodies in the United States and Britain.
"Climate extremes, including devastating floods, severe and persistent droughts, snow storms, heat waves and cold waves were recorded in many parts of the world," the agency said. In many of these, hundreds or even thousands of people died.
Among the disasters was Cyclone Nargis, which killed some 78,000 in Myanmar's southern delta region in early May. In the western Atlantic and Caribbean there were 16 major tropical storms, eight of which developed into hurricanes.
In an average year, there are 11 storms of which six become hurricanes and two become major hurricanes. In 2008, five major hurricanes developed, and for the first time on record six tropical storms in a row made landfall in the United States.
The WMO says the 10 hottest years since global records were first kept in 1850 have all been since 1997, with the warmest at 14.79 C in 2005. Countries have been struggling for years to reach agreement on how to halt the trend.
This month a two-week meeting of leaders in Poznan, Poland, called to prepare a treaty for late 2009 seemed to falter amid rows between rich and poor nations and what some climate campaigners say was lack of will to get things done.
-- Additional reporting by Gerard Wynn and Michael Szabo in London
Editing by Stephanie Nebehay and Michael Roddy