Study reveals lakes a major source of prehistoric methaneOctober 26, 2007
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
Where did the missing oil go? New FSU study says some is sitting on the Gulf floor
After 200 million gallons of crude oil spilled into the Gulf of Mexico in April 2010, the government and BP cleanup crews mysteriously had trouble locating all of it.
Cheap asphalt provides 'green' carbon capture
The best material to keep carbon dioxide from natural gas wells from fouling the atmosphere may be a derivative of asphalt, according to Rice University scientists.
Methane is leaking from permafrost offshore Siberia
Yamal Peninsula in Siberia has recently become world famous. Spectacular sinkholes, appeared as out of nowhere in the permafrost of the area, sparking the speculations of significant release of greenhouse gas methane into the atmosphere.
Rice study fuels hope for natural gas cars
Cars that run on natural gas are touted as efficient and environmentally friendly, but getting enough gas onboard to make them practical is a hurdle. A new study led by researchers at Rice University promises to help.
Damming beavers are slowly changing the world
There are consequences of the successful efforts worldwide to save beavers from extinction. Along with the strong increase in their population over the past 100 years, these furry aquatic rodents have built many more ponds, establishing vital aquatic habitat.
Back to the future? Past global warming period echoes today's
The rate at which carbon emissions warmed Earth's climate almost 56 million years ago resembles modern, human-caused global warming much more than previously believed, but involved two pulses of carbon to the atmosphere, researchers have found.
No laughing matter: Nitrous oxide rose at end of last ice age
Nitrous oxide (N2O) is an important greenhouse gas that doesn't receive as much notoriety as carbon dioxide or methane, but a new study confirms that atmospheric levels of N2O rose significantly as the Earth came out of the last ice age and addresses the cause.
New Study Measures Methane Emissions from Natural Gas Production and Offers Insights into Two Large Sources
A team of researchers from the Cockrell School of Engineering at The University of Texas at Austin and environmental testing firm URS reports that a small subset of natural gas wells are responsible for the majority of methane emissions from two major sources - liquid unloadings and pneumatic controller equipment - at natural gas production sites.
New form of ice could help explore exciting avenues for energy production and storage
Clathrates are now known to store enormous quantities of methane and other gases in the permafrost as well as in vast sediment layers hundreds of metres deep at the bottom of the ocean floor.
Abandoned wells can be 'super-emitters' of greenhouse gas
Princeton University researchers have uncovered a previously unknown, and possibly substantial, source of the greenhouse gas methane to the Earth's atmosphere.
More Methane Current Events and Methane News Articles