时代杂志专文：全球变暖如何让暴风雪来得更猛烈？

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时代杂志专文：How Global Warming Makes Blizzards Worse由 zhang3you » 周四 2月 11, 2010 3:43 am
D.C. Snowstorm: How Global Warming Makes Blizzards Worse
By BRYAN WALSH Bryan Walsh
Wed Feb 10, 2009，7:30 am ET

As the blizzard-bound residents of the mid-Atlantic region get ready to dig themselves out of the third major storm of the season, they may stop to wonder two things: Why haven't we bothered to invest in a snow blower and, also, what happened to climate change? After all, it stands to reason that if the world is getting warmer - and the past decade was the hottest on record - major snowstorms should become a thing of the past, like Palm Pilots and majority rule in the Senate. Certainly that's what the Virginia state Republican Party thinks: the GOP aired an ad last weekend attacking two Democratic Congressmen for supporting the 2009 carbon-cap-and-trade bill, and using the recent storms to cast doubt on global warming. (See pictures of a massive blizzard hitting Washington, D.C.)

Brace yourselves now - this may be a case of politicians twisting the facts. There is some evidence that climate change could in fact make such massive snowstorms more common, even as the world continues to warm. As the meteorologist Jeff Masters points out in his excellent blog at Weather Underground, the two major storms that hit Philadelphia, Baltimore and Washington, D.C., this winter - in December and during the first weekend of February - are already among the 10 heaviest snowfalls those cities have ever recorded. The chance of that happening in the same winter is incredibly unlikely.

But there have been hints that it was coming. The 2009 U.S. Climate Impacts Report found that large-scale cold-weather storm systems have gradually tracked to the north in the U.S. over the past 50 years. While the frequency of storms in the middle latitudes has decreased as the climate has warmed, the intensity of those storms has increased. That's in part because of global warming - hotter air can hold more moisture, so when a storm gathers it can unleash massive amounts of snow. Colder air, by contrast, is drier; if we were in a truly vicious cold snap, like the one that occurred over much of the East Coast during parts of January, we would be unlikely to see heavy snowfall. (See pictures of the effects of global warming.)

Climate models also suggest that while global warming may not make hurricanes more common, it could well intensify the storms that do occur and make them more destructive.

But as far as winter storms go, shouldn't climate change make it too warm for snow to fall? Eventually that is likely to happen - but probably not for a while. In the meantime, warmer air could be supercharged with moisture and, as long as the temperature remains below 32°F, it will result in blizzards rather than drenching winter rainstorms. And while the mid-Atlantic has borne the brunt of the snowfall so far this winter, areas near lakes may get hit even worse. As global temperatures have risen, the winter ice cover over the Great Lakes has shrunk, which has led to even more moisture in the atmosphere and more snow in the already hard-hit Great Lakes region, according to a 2003 study in the Journal of Climate. (Read "Climate Accord Suggests a Global Will, if Not a Way.")

Ultimately, however, it's a mistake to use any one storm - or even a season's worth of storms - to disprove climate change (or to prove it; some environmentalists have wrongly tied the lack of snow in Vancouver, the site of the Winter Olympic Games, which begin this month, to global warming). Weather is what will happen next weekend; climate is what will happen over the next decades and centuries. And while our ability to predict the former has become reasonably reliable, scientists are still a long way from being able to make accurate projections about the future of the global climate. Of course, that doesn't help you much when you're trying to locate your car under a foot of powder.

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关键词：全球变暖 暴风雪 environment Underground Large-Scale Global 气候变化 Climate 全球变暖 Warming

World warming unhindered by cold spells: scientists
By David Fogarty, Climate Change Correspondent, Asia David Fogarty, Climate Change Correspondent, Asia 2/25/2010

SINGAPORE (Reuters) – The pace of global warming continues unabated, scientists said on Thursday, despite images of Europe crippled by a deep freeze and parts of the United States blasted by blizzards.

The bitter cold, with more intense winter weather forecast for March in parts of the United States, have led some to question if global warming has stalled.
Understanding the overall trend is crucial for estimating consumption of energy supplies, such as demand for winter heating oil in the U.S. northeast, and impacts on agricultural production.

"It's not warming the same everywhere but it is really quite challenging to find places that haven't warmed in the past 50 years," veteran Australian climate scientist Neville Nicholls told an online climate science media briefing.

"January, according to satellite (data), was the hottest January we've ever seen," said Nicholls of Monash University's School of Geography and Environmental Science in Melbourne.
"Last November was the hottest November we've ever seen, November-January as a whole is the hottest November-January the world has seen," he said of the satellite data record since 1979.


The World Meteorological Organization (WMO) said in December that 2000-2009 was the hottest decade since records began in 1850, and that 2009 would likely be the fifth warmest year on record. WMO data show that eight out of the 10 hottest years on record have all been since 2000.

Britain's official forecaster, the UK Met Office, said severe winter freezes like the one this year, one of the coldest winters in the country for nearly 30 years, could become increasingly rare because of the overall warming trend.

MORE EXTREMES

Scientists say global warming is not uniform in all areas and that climate models predict there will likely be greater extremes of cold and heat, floods and droughts.
"Global warming is a trend superimposed upon natural variability, variability that still exists despite global warming," said Kevin Walsh, associate professor of meteorology at the University of Melbourne.

"It would be much more surprising if the global average temperature just kept on going up, year after year, without some years of slightly cooler temperatures," he said in a written reply to questions for the briefing.

The scientists also defended the U.N. climate panel after it came under attack for including an error about the estimated thaw of Himalayan glaciers in a major 2007 report.
The Intergovernmental Panel on Climate Change (IPCC) produces reports based on the work of thousands of scientists that are the main guides for policymakers on tackling global warming. The discovery of the error has been seized upon by climate skeptics.

The 2007 report wrongly said Himalayan glaciers could all melt by 2035, an apparent typographical error that stemmed from using "grey literature" outside peer-reviewed scientific journals.
Nicholls said grey literature could play a key role in the climate debate and that not all valuable data or reports were published formally in journals. Such examples included reports on extreme weather events by government meteorological agencies.

"The IPCC does not exclude the use of that sort of grey literature because it would be stupid to talk about extremes, for instance, and not include that sort of grey literature," he said.
The scientists said more stringent checks were needed for the next IPCC reports but that the inclusion of one or two wrong predictions didn't undermine the whole peer-reviewed IPCC process because scientific study was always evolving. (Editing by Paul Tait)