GENEVA — Global warming accelerated since the 1970s and broke more countries' temperature records than ever before in the first decade of the new millennium, U.N. climate experts said Wednesday.
A new analysis from the World Meteorological Organization says average land and ocean surface temperatures from 2001 to 2010 rose above the previous decade, and were almost a half-degree Celsius above the 1961-1990 global average.
The decade ending in 2010 was an unprecedented era of climate extremes, the agency said, evidenced by heat waves in Europe and Russia, droughts in the Amazon Basin, Australia and East Africa, and huge storms like Tropical Cyclone Nargis and Hurricane Katrina.
Data from 139 nations show that droughts like those in Australia, East Africa and the Amazon Basin affected the most people worldwide. But it was the hugely destructive and deadly floods such as those in Pakistan, Australia, Africa, India and Eastern Europe that were the most frequent extreme weather events.
Experts say a decade is about the minimum length of time to study when it comes to spotting climate change.
From 1971 to 2010, global temperatures rose by an average rate of 0.17 degrees Celsius per decade. But going back to 1880, the average increase was .062 percent degrees Celsius per decade.
The pace also picked up in recent decades. Average temperatures were 0.21 degrees Celsius warmer this past decade than from 1991 to 2000, which were in turn 0.14 degrees Celsius warmer than from 1981 to 1990.
Natural cycles between atmosphere and oceans make some years cooler than others, but during the past decade there was no major event associated with El Nino, the phenomenon characterized by unusually warm temperatures in the equatorial Pacific Ocean. Much of the decade was affected by the cooling La Nina, which comes from unusually cool temperatures there, or neutral conditions.
Given those circumstances, WMO Secretary-General Michel Jarraud says the data doesn't support the notion among some in the scientific community of a slowdown, or lull, in the pace of planetary warming in recent years.
"The last decade was the warmest, by a significant margin," he said. "If anything we should not talk about the plateau, we should talk about the acceleration."
Jarraud says the data show warming accelerated between 1971 and 2010, with the past two decades increasing at rates never seen before amid rising concentrations of industrial gases that trap heat in the atmosphere like a greenhouse.
By the end of 2010, the report shows, atmospheric concentrations of some of the chief warming gases from fossil fuel burning and other human actions were far higher than at the start of the industrial era in 1750. Carbon dioxide concentrations measured in the air around the world rose 39 percent since then; methane rose 158 percent; and nitrous oxide was up 20 percent.