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Updated: Thu, 04 Jul 2013 02:33:35 GMT | By CBC News, cbc.ca

Last decade warmest on record, says UN report



Last decade warmest on record, says UN report

The first decade of the 21st century was the world's warmest in 160 years and was marked by a number of extreme climate events, a United Nations agency has found.

A new report by the World Meteorological Organization says that in the period between 2001 and 2010, global warming accelerated since the 1970s and broke more countries' temperature records than ever before.

The report, released on Wednesday, says the period was the "warmest decade on record since modern meteorological records began around the year 1850."

Average land and ocean surface temperatures from 2001 to 2010 rose above the previous decade and were almost a half-degree above the 1961-90 global average.

Canada's average temperature rose by 1.3 degrees during that period, making it the country's warmest decade, according to the agency.

While the warming trend in Canada has been most evident in northern regions, many climate scientists say they're not surprised to hear the UN agency is linking the global warming trend to a worldwide increase in extreme weather.

"We'll definitely see climate impacts, and we are already seeing climate impacts now and as an ongoing issue, unfortunately," said Deborah Harford of the Adaptation to Climate Change think-tank at Simon Fraser University.

"All across Canada, people are experiencing everything from major rainstorms to major flooding and drought."

Unprecedented era

The World Meteorological Organization report says the decade ending in 2010 was an unprecedented era of climate extremes, as shown by heat waves in Europe and Russia, droughts in the Amazon Basin, Australia and East Africa, and huge storms such as Cyclone Nargis in Asia and Hurricane Katrina in the United States.

Data from 139 nations show that droughts such as those in Australia, East Africa and the Amazon Basin affected the most people worldwide.

However, 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.

"Climate change has reshaped the behaviour of climate extremes," said Omar Baddour, the World Meteorological Organization's co-ordinator.

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 per decade. But going back to 1880, the average increase was .062 degrees per decade.

The pace also picked up in recent decades. Average temperatures were 0.21 degrees warmer this past decade than from 1991 to 2000, which were in turn 0.14 degrees warmer than from 1981 to 1990.

The agency was quick to note that while natural climate variability may account for some of the extreme weather, human factors cannot be ignored.

"Many of these events and trends can be explained by the natural variability of the climate system. Rising atmospheric concentrations of greenhouse gases, however, are also affecting the climate," the report's summary states in part.

"Detecting the respective roles being played by climate variability and human-induced climate change is one of the key challenges facing researchers today."

No lull in global warming, says official

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, World Meteorological Organization secretary general Michel Jarraud said 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 said 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 per cent since then; methane rose 158 per cent; and nitrous oxide was up 20 per cent.

Regardless of what is causing the warming trend, environmental groups say the report paints a clearer picture of a warming world.

"It really pushes back on some of the skeptics who say, 'Well, you can't count one hot year as climate change.' What we're seeing is an overall trend, and the study really highlights that quite clearly," said Gillian McEachern, campaigns director with Environmental Defence in Ottawa.

Food supply threatened, Canadian report warns

A report from Simon Fraser's Adaptation to Climate Change team, also released on Wednesday, warns that climate change is threatening water supplies and could lead to shortages of local or regional products such as British Columbia wild salmon and western Canadian beef and grain.

Changing weather patterns could alter the conditions that favour the production of ice wine, maple sugar and, further afield, fruits and vegetables that are imported from California, the report added.

"Climate change is already here, and adapting to this new reality is critical in the years ahead, particularly as agriculture and the global food supply are impacted by the fact that water is becoming increasingly scarce at home and abroad," Harford said in a release.

"Here in British Columbia and Canada, there's no question that our food supply is going to change, and change quickly in the coming years."

The World Meteorological Organization says its report doesn't provide immediate solutions, as more study and data are required.

"A decade is the minimum possible time frame for detecting temperature changes," the report states in part.

"Assessing trends in extreme weather and climate events requires an even longer time frame because, by definition, these events do not occur frequently."

With files from The Associated Press

External Links

World Meteorological Organization
Simon Fraser University: Adaptation to Climate Change team

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