The Weekend Australian
By: Robert Lee Hotz Source: The Wall Street Journal
The exceptionally unusual becomes the new normal, writes Robert Lee Hotz
Three independent research groups have concluded that last year was a comparatively cool one on planet Earth -- a feverish chill on our warming world.
The year's average global temperature was the 9th or 10th warmest since reliable record-keeping began in 1850, and the coldest since the turn of the 21st century, according to separate surveys by the UN's World Meteorological Organisation, NASA's Goddard Institute of Space Studies, and the US National Climatic Data Centre.
Each used slightly different methods to rank 2008 based on world-wide land and sea-surface temperatures through to November. For the time being, no one knows whether this temperature drop heralds a lasting retreat from global warming or a temporary dip.
Temperatures in October were the warmest for that month in more than a century, government weather records show. Overall, the year ran slightly less than one degree Fahrenheit warmer than the 20th century mean.
In matters of climate, the unusual is becoming routine, as higher temperatures make weather patterns more unstable.
"As a result of climate change,'' says Peter Stott, head of climate monitoring at Britain's Hadley Centre, which helped prepare the UN figures, "what would have once been an exceptionally unusual year has now become quite normal.''
Despite the ups and downs of annual temperature swings, the planet has grown steadily warmer in recent decades, affecting everything from New England winters and the Siberian spring to western droughts and tropical cloud cover.
That's according to eight new government and university climate studies presented last month during a meeting in San Francisco of the American Geophysical Union, an international scientific society of 50,000 researchers who study Earth and its environment.
Almost all of the warming in North America has taken place since 1970, says a team of government and academic experts at the US Climate Change Science Program.
Looking beyond the variations of any single year, these studies chronicle growing evidence of climate changes and suggest the effects of rising temperatures are accelerating.
"I do believe we are entering a new state,'' says Arctic researcher Julienne Stroeve at the National Snow and Ice Data Centre in Boulder, Colorado.
"Ice loss is happening faster than the climate models are showing.''
Since 2003, more than two trillion tons of land ice in Greenland, Antarctica and Alaska have melted, adding enough water to oceans to raise global sea level by one-fifth of an inch (5mm), NASA geophysicists reported at the conference. Alaska's low-lying ice fields are disappearing at up to three times the rate of a decade ago, based on aerial surveys by University of Alaska researchers. Since 2000, Greenland alone has lost 355.4 square miles (920.5sq km) of ice, Ohio State University researchers reported. Using data from two NASA satellites, they determined that Greenland's 32 largest glaciers lost three times as much ice last year as the year before.
"I wouldn't run for the hills,'' says glacier analyst Eric Rignot at NASA's Jet Propulsion Laboratory, "but it might be time to start walking.''
In another sign of polar thaw, researchers have detected new seeps of methane bubbling up from formerly frozen sea-floor lodes along the Siberian coast. Methane, like carbon dioxide, is a potent greenhouse gas that helps trap heat in the atmosphere and could accelerate any warming trend.
"We have enough data to worry,'' says Igor Semiletov at the University of Alaska Fairbanks, who reported the methane leaks. Warming temperatures are also influencing more temperate latitudes, several recent studies show. By analysing five years' worth of infra-red measurements from NASA's Aqua satellite, JPL researchers found that high-altitude tropical storm and rain clouds are increasing. At the present rate of warming, the scientists reported last month, tropical storms can be expected to increase by 6 per cent every 10 years.
Solar heat is the energy that drives the world's weather, and rising levels of greenhouse gases such as carbon dioxide and methane are allowing more of that energy to build up in the atmosphere every year, experts say.
Overall, the world's atmosphere warmed by 0.72 degrees Fahrenheit during the past 30 years, according to a comprehensive analysis of monthly satellite temperature readings by John Christy, head of the Earth System Science Centre at the University of Alabama in Huntsville, which was released last month.
But on the hot plate of planet Earth, that warming is not evenly distributed. Changing sea ice, ocean currents and winds mute or accelerate regional temperature changes by redistributing the heat in the atmosphere.
A quarter of the globe warmed at least one full degree Fahrenheit since the satellite readings started in 1978.
The warming was most pronounced in northern latitudes. A few isolated areas in Antarctica actually cooled by at least half of one degree Fahrenheit. So many subtle changes in so many different places, building up decade after decade, add up to something more than the weather's natural variation.
To a seasoned eye, day-to-day weather patterns seem chaotic.
Among the Inuit of the eastern Canadian Arctic, University of Colorado researchers reported last month, many elders are no longer willing to trust their forecasting skills, which have been honed by a life in the field, to guide local hunting parties and travellers.
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Column: The Wall Street Journal
Section: WORLD