Alaska Lake Boils With Escaping Methane
ENS
"The violent streams of bubbles made the lake appear as if it were boiling, but the water was pretty cold," she said.
Walter studies methane emissions from arctic lakes, especially the connection between thawing permafrost and climate change.
As permafrost around a lake's edges thaws, the organic material in it - dead plants and animals - can enter the lake bottom, where bacteria convert it to methane, which bubbles into the atmosphere.
Methane is a one of the six greenhouse gases governed by the Kyoto Protocol. Methane is over 20 times more effective in trapping heat in the atmosphere than carbon dioxide. It remains in the atmosphere for between nine and 15 years.
Walter said this summer's fieldwork indicates that methane hotspots can come from various sources, not just thawing permafrost.
Methane is emitted from a variety of human sources such as landfills, natural gas and petroleum systems, agricultural activities, coal mining, stationary and mobile combustion, wastewater treatment, and certain industrial processes. Methane is also a primary constituent of natural gas and can be captured from landfills or other sources and burned to produce energy.
Walter's next goal is to identify and quantify the sources of the methane hotspots around Alaska.
"It is unlikely that this methane plume was related to permafrost thaw," said Walter, adding that the methane boiling out of the lake was more likely related to natural gas seepage.
"Should large quantities of methane be released from methane hydrates, for instance, in association with permafrost thaw," she said, "then we could have large sudden increases in atmospheric methane with potentially large affects on global temperatures."
Walter's project is one of many at the university being conducted as part of the International Polar Year, an international event that is focusing research efforts and public attention on the Earth's polar regions.
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