Related News
Reprieve on global warming
A STUDY of Greenland's ice sheet has revealed that a vast store of planet-warming methane appears to be more stable than thought, easing fears of a rapid rise in temperatures, a scientist said yesterday.
Methane is about 25 times more powerful at trapping heat in the atmosphere than carbon dioxide and vast amounts of the compound are trapped in permafrost in the far northern hemisphere or in seabed deposits called clathrates.
Scientists have feared climate change could trigger a huge release of methane from the clathrate reservoir, sending global warming spiraling out of control.
An estimated 5,000 billion tons of carbon are locked up in these deposits, said Vasilii Petrenko of the Institute of Arctic and Alpine Research at the University of Colorado. "That's about equal to all of the oil, coal and gas reserves that we think we have," he said.
Petrenko and an international team of scientists spent six years studying air samples from vast blocks of Greenland ice to see if a rapid rise in temperatures about 12,000 years ago was triggered by methane from clathrates or another source.
The results showed the methane was most likely to have come from wetlands rather than the clathrates, deposits which resemble ice and are held in place on the ocean bed by high pressures and relatively low temperatures.
Petrenko said temperatures in Greenland 12,000 years ago had increased about 10 degrees Celsius in 20 years.
But it took 150 years for methane levels in the atmosphere to increase by 50 percent.
The rapid warming was driving the release of methane, he said, with the most likely sources being tropical wetlands and the vast northern wetlands created after the large-scale retreat of ice sheets about 18,000 years ago.
Methane is about 25 times more powerful at trapping heat in the atmosphere than carbon dioxide and vast amounts of the compound are trapped in permafrost in the far northern hemisphere or in seabed deposits called clathrates.
Scientists have feared climate change could trigger a huge release of methane from the clathrate reservoir, sending global warming spiraling out of control.
An estimated 5,000 billion tons of carbon are locked up in these deposits, said Vasilii Petrenko of the Institute of Arctic and Alpine Research at the University of Colorado. "That's about equal to all of the oil, coal and gas reserves that we think we have," he said.
Petrenko and an international team of scientists spent six years studying air samples from vast blocks of Greenland ice to see if a rapid rise in temperatures about 12,000 years ago was triggered by methane from clathrates or another source.
The results showed the methane was most likely to have come from wetlands rather than the clathrates, deposits which resemble ice and are held in place on the ocean bed by high pressures and relatively low temperatures.
Petrenko said temperatures in Greenland 12,000 years ago had increased about 10 degrees Celsius in 20 years.
But it took 150 years for methane levels in the atmosphere to increase by 50 percent.
The rapid warming was driving the release of methane, he said, with the most likely sources being tropical wetlands and the vast northern wetlands created after the large-scale retreat of ice sheets about 18,000 years ago.
- About Us
- |
- Terms of Use
- |
-
RSS
- |
- Privacy Policy
- |
- Contact Us
- |
- Shanghai Call Center: 962288
- |
- Tip-off hotline: 52920043
- 娌狪CP璇侊細娌狪CP澶05050403鍙-1
- |
- 浜掕仈缃戞柊闂讳俊鎭湇鍔¤鍙瘉锛31120180004
- |
- 缃戠粶瑙嗗惉璁稿彲璇侊細0909346
- |
- 骞挎挱鐢佃鑺傜洰鍒朵綔璁稿彲璇侊細娌瓧绗354鍙
- |
- 澧炲肩數淇′笟鍔$粡钀ヨ鍙瘉锛氭勃B2-20120012
Copyright 漏 1999- Shanghai Daily. All rights reserved.Preferably viewed with Internet Explorer 8 or newer browsers.