Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Wetlands likely source of methane from ancient warming event

27.04.2009
Analysis of Greenland ice led by Scripps researchers could allay fears about methane 'burp' accelerating current global warming trend

An expansion of wetlands and not a large-scale melting of frozen methane deposits is the likely cause of a spike in atmospheric methane gas that took place some 11,600 years ago, according to an international research team led by Scripps Institution of Oceanography at UC San Diego.

The finding is expected to come as a relief to scientists and climate watchers concerned that huge accelerations of global warming might have been touched off by methane melts in the past and could happen again now as the planet warms. By measuring the amount of carbon-14 isotopes in methane from air bubbles trapped in glacial ice, the researchers determined that the surge that took place nearly 12,000 years ago was more chemically consistent with an expansion of wetlands. Wetland regions, which produce large amounts of methane from bacterial breakdown of organic matter, are known to have spread during warming trends throughout history.

"This is good news for global warming because it suggests that methane clathrates do not respond to warming by releasing large amounts of methane into the atmosphere," said Vasilii Petrenko, a postdoctoral fellow at University of Colorado, Boulder, who led the analysis while a graduate student at Scripps.

The results appear in April 24 editions of the journal Science.

Scientists had long been concerned about the potential for present-day climate change to cause a thawing of Arctic permafrost and a warming of ocean waters great enough to trigger a huge release of methane that would send planetary warming into overdrive. Vast amounts of methane are sequestered in solid form, known as methane clathrate, in seafloor deposits and in permafrost. Cold temperatures and the intense pressure of the deep ocean stabilize the methane clathrate masses and keep methane from entering the atmosphere.

Scientists have estimated that a melting of only 10 percent of the world's clathrate deposits would create a greenhouse effect equal to a tenfold increase in the amount of carbon dioxide in the atmosphere. For comparison, the warming trend observed in the last century has taken place with only a 30 percent increase of atmospheric carbon dioxide.

The research team, overseen by Scripps geoscientist and study co-author Jeff Severinghaus, collected what may be the largest ice samples ever for a climate change study. The researchers cut away 15 tons of ice from a site called Pakitsoq at the western margin of the Greenland ice sheet to collect the ancient air trapped within. Methane exists in low concentrations in this air and only a trillionth of any given amount contains the carbon-14 isotope that the researchers needed to perform the analysis. Levels of carbon-14, which has a half-life of 5,730 years, were too high in the methane to have come from clathrates, the researchers concluded.

"This study is important because it confirms that wetlands and moisture availability change dramatically along with abrupt climate change," said Severinghaus. "This highlights in a general way the fact that the largest impacts of future climate change may be on water resources and drought, rather than temperature per se."

The burst of methane took place immediately after an abrupt transition between climatic periods known as the Younger Dryas and Preboreal. During this event, temperatures in Greenland rose 10° C (18° F) in 20 years. Methane levels over 150 years rose about 50 percent, from 500 parts per billion in air to 750 parts per billion.

In addition to Petrenko and Severinghaus, researchers from the Australian Nuclear Science and Technology Organisation (ANSTO), Oregon State University, the National Institute of Water and Atmospheric Research in New Zealand, the Technical University of Denmark and the Commonwealth Scientific and Industrial Research Organisation in Australia contributed to the report.

The work was supported by grants from the National Science Foundation, the Packard Foundation, the American Chemical Society, the ANSTO Cosmogenic Climate Archives of the Southern Hemisphere project and the New Zealand Foundation of Science and Technology.

Scripps Institution of Oceanography:

Scripps Institution of Oceanography, at UC San Diego, is one of the oldest, largest and most important centers for global science research and education in the world. The National Research Council has ranked Scripps first in faculty quality among oceanography programs nationwide. Now in its second century of discovery, the scientific scope of the institution has grown to include biological, physical, chemical, geological, geophysical and atmospheric studies of the earth as a system. Hundreds of research programs covering a wide range of scientific areas are under way today in 65 countries. The institution has a staff of about 1,300, and annual expenditures of approximately $155 million from federal, state and private sources. Scripps operates one of the largest U.S. academic fleets with four oceanographic research ships and one research platform for worldwide exploration.

Robert Monroe | EurekAlert!
Further information:
http://www.ucsd.edu
http://scrippsnews.ucsd.edu
http://scripps.ucsd.edu

More articles from Earth Sciences:

nachricht NASA looks to solar eclipse to help understand Earth's energy system
21.07.2017 | NASA/Goddard Space Flight Center

nachricht Scientists shed light on carbon's descent into the deep Earth
19.07.2017 | European Synchrotron Radiation Facility

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>