Methane Bubbles from Arctic Lakes Measured from Space as Atmospheric Levels Reach Peak

Bubbles of methane coming from lakes in the Arctic are being measured from space so scientists can better understand their role in emissions of the potent greenhouse gas.

A report from NASA Earth Observatory has looked at the work of Melanie Engram, from the University of Alaska, after she and her team harnessed satellite technology to estimate emissions from a portion of the millions of lakes in this region of the world.

This comes as two studies show atmospheric methane levels have reached record levels, with emissions increasing by almost 10 percent over the last 20 years—largely due to increases in the gas and agriculture industries. Findings show methane concentrations reached 1,875 parts per billion by the end of 2019. This is over 2.5 times higher than they were before the Industrial Revolution.

Methane only lasts in the atmosphere for around a decade, compared with carbon dioxide, which stays for between 300 and 1,000 years. However, it's warming potential is almost 90 times higher than CO2 over a 20 year period.

Writing in The Conversation, the authors of the atmospheric concentration studies said the rate atmospheric methane is increasing is consistent with the Intergovernmental Panel on Climate Change models where global warming increases by between three to four degrees Celsius by 2020. They said that between 2008 and 2016, 60 percent of methane emissions were man-made.

Understanding the sources of methane is important for understanding how the world is warming and creating more accurate climate change models.

In the Arctic, tiny organisms that live in lakes break down organic matter and release methane. While an individual lake may not amount to much methane, over the estimated 3.6 million lakes in the Arctic, it adds up.

Engram and her team used satellites to measure the methane coming from the lakes and entering the atmosphere from over 5,000 of the 134,000 lakes in Alaska. They then took these satellite observations and compared them with ground-based measurements at various lakes.

Their findings, published in Nature Climate Change, show smaller lakes had the biggest fluxes in methane release, but larger lakes were responsible for emitting more gas. It is thought the smaller lakes produced larger bursts of methane because they tend to sit on permafrost. This is permanently frozen ground that is rich in organic material. When the ground thaws, this material starts breaking down and releases large amounts of methane in the process.

methane bubbles
Stock image showing methane bubbles frozen in a lake in Canada. Researchers have studied methane emissions from Arctic lakes using a satellite-based system. iStock

There is a large concern about the role permafrost will play in the future as it could result in a positive feedback loop—as permafrost thaws and releases methane, global temperatures will increase further, leading to greater permafrost thaw and even more warming.

The team say their remote sensing technique for methane release from lakes provides a way to improve our understanding of methane release from the Arctic. This, they say, could help explain discrepancies between estimates of methane release and atmospheric measurements.

Engram told NASA Earth Observatory they hope to extend their analysis across other Arctic regions: "There is plenty available for Alaska, Canada, and Greenland. The biggest challenges will be Russia, the largest region of the Arctic, but where...coverage is very sparse."