Study points to methane from Arctic lakes

A research study published in March in Geobiology has shed new light on the sources of methane emitted from thermokarst lakes on Alaska’s North Slope. A thermokarst lake forms in a surface depression where meltwater from previously frozen ground accumulates. Under scenarios of increasing global temperatures, microbes in lake sediments generate methane gas, the research found.

Methane is a potent greenhouse gas that can make a significant contribution to global warming.

Over a period of four years the researchers collected sediment cores from two lakes near Barrow, at the northwestern extremity of the North Slope - a large amount of organic matter in the thaw layer between the lake water and the underlying permafrost serves as a significant carbon source for methane generation, the researchers found.

Using simulated climate scenarios in a laboratory in Reno, Nevada, the researchers investigated the potential for the increased biological generation of methane from sediment samples and assessed the impacts of sediment geochemistry and the temperature on methane production.

“In scenarios of warming climate our measurements indicate that biological methane production may play a larger role in total methane emissions in the future, which could have a significant impact on our climate,” said Alison Murray, a principal investigator in the study.

This methane comes in addition to thermally generated methane released from methane deposits deep underground.

The study marks an important step in recognizing that different methane sources in close proximity may respond differently in the changing Arctic ecosystems, Murray said.

- Alan Bailey