Study reveals lakes a major source of prehistoric methaneOctober 26, 2007
A team of scientists led by a researcher at the University of Alaska Fairbanks has identified a new likely source of a spike in atmospheric methane coming out of the North during the end of the last ice age.
Methane bubbling from arctic lakes could have been responsible for up to 87 percent of that methane spike, said UAF researcher Katey Walter, lead author of a report printed in the Oct. 26 issue of Science magazine. The findings could help scientists understand how current warming might affect atmospheric levels of methane, a gas that is thought to contribute to climate change.
"It tells us that this isn't just something that is ongoing now. It would have been a positive feedback to climate warming then, as it is today," said Walter. "We estimate that as much as 10 times the amount of methane that is currently in the atmosphere will come out of these lakes as permafrost thaws in the future. The timing of this emission is uncertain, but likely we are talking about a time frame of hundreds to thousands of years, if climate warming continues as projected."
Ice cores from Greenland and Antarctica have shown that during the early Holocene Period--about 14,000 to 11,500 years ago--the levels of methane in the atmosphere rose significantly, Walter said. "They found that an unidentified northern source (of methane) appeared during that time."
Previous hypotheses suggested that the increase came from gas hydrates or wetlands. This study's findings indicate that methane bubbling from thermokarst lakes, which are formed when permafrost thaws rapidly, is likely a third and major source.
Walter's research focused on areas of Siberia and Alaska that, during the last ice age, were dry grasslands atop ice-rich permafrost. As the climate warmed, Walter said, that permafrost thawed, forming thermokarst lakes.
"Lakes really flared up on this icy permafrost landscape, emitting huge amounts of methane," she said.
As the permafrost around and under the lakes thaws, the organic material in it--dead plants and animals--can enter the lake bottom and become food for the bacteria that produce methane.
"All that carbon that had been locked up in the ground for thousands of years is converted to potent greenhouse gases: methane and carbon dioxide," Walter said. Walter's paper hypothesizes that methane from the lakes contributed 33 to 87 percent of the early Holocene methane increase.
To arrive at the hypothesis, Walter and her colleagues traveled to Siberia and northern Alaska to examine lakes that currently release methane. In addition, they gathered samples of permafrost and thawed them in the laboratory to study how much methane permafrost soil can produce immediately after thawing.
"We found that it produced a lot very quickly," she said.
Finally, she and other researchers studied when existing lakes and lakes in the past formed and found that their formation coincided with the early Holocene Period northern methane spike.
"We came up with a new hypothesis," she said. "Thermokarst lake formation is a source of atmospheric methane today, but it was even more important during early Holocene warming. This suggests that large releases from lakes may occur again in the future with global warming."
Co-authors on the paper include Mary Edwards of the University of Southampton and the UAF College of Natural Science and Mathematics; Guido Grosse, an International Polar Year postdoctoral fellow with the UAF Geophysical Institute; Sergey Zimov of the Russian Academy of Sciences; and Terry Chapin of the UAF Institute of Arctic Biology. Funding was provided by the National Science Foundation, the Environmental Protection Agency and the National Aeronautics and Space Administration.
University of Alaska Fairbanks
Related Methane Current Events and Methane News Articles
Hydrothermal vents, methane seeps play enormous role in marine life, global climate
The hydrothermal vents and methane seeps on the ocean floor that were once thought to be geologic and biological oddities are now emerging as a major force in ocean ecosystems, marine life and global climate.
Arctic Ocean methane does not reach the atmosphere
250 methane flares release the climate gas methane from the seabed and into the Arctic Ocean.
Scientists discover methane-producing microbes in California rocks
Deep in vents on the ocean floor, methane-producing microbes feed off chemical reactions between water and rock. Now evidence of this process has been found on land in a freshwater spring in California.
Barium leaches directly from fracked rocks, Dartmouth team finds
Dartmouth College researchers are shedding light on the early chemical reactions in the organic sediments that would ultimately become the Marcellus Shale, a major source of natural gas and petroleum.
Chemists settle longstanding debate on how methane is made biologically
Like the poet, microbes that make methane are taking chemists on a road less traveled: Of two competing ideas for how microbes make the main component of natural gas, the winning chemical reaction involves a molecule less favored by previous research, something called a methyl radical.
Paris climate agreement cannot be met without emissions reduction target for agriculture
Scientists have calculated, for the first time, the extent to which agricultural emissions must be reduced to meet the new climate agreement's plan to limit warming to 2¬°C in 2100.
Retreat of the ice followed by millennia of methane release
Scientists have calculated that the present day ice sheets keep vast amounts of climate gas methane in check.
Finnish research shows inaccuracies in emission measurements of important greenhouse gas, N2O
Nitrous oxide, carbon dioxide and methane are the most important greenhouse gases. Nitrous oxide also participates in the destruction of stratospheric ozone.
Researchers integrate diamond/boron nitride crystalline layers for high-power devices
Materials researchers at North Carolina State University have developed a new technique to deposit diamond on the surface of cubic boron nitride (c-BN), integrating the two materials into a single crystalline structure.
Methane production reduced in ruminants
Researchers at the Spanish National Research Council (CSIC) have taken part in a study of the effect of one molecule, 3-nitrooxypropanol, in inhibiting methane production in ruminants.
More Methane Current Events and Methane News Articles