A ticking time bomb of Arctic greenhouse gases is now visible from space.
For the first time, scientists have used satellites to detect methane escaping into the atmosphere from melting permafrost. Data from a Japanese probe revealed an icy landscape transformed by “rising methane bubbles,” Nature reported.
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The project was presented this week at the American Geophysical Union meeting in Washington, DC.
“It’s really exciting,” Melanie Engram, a remote-sensing scientist at the University of Alaska Fairbanks, told Nature. “We can see roughness in the ice—divots created by methane bubbles.”
Engram and a team of researchers tapped into radar measurements from Japan’s Advanced Land Observing Satellite. In the last decade, Japan has launched a fleet of satellites designed to monitor changes across Earth’s surface and atmosphere.
The satellite measured fluctuations in ground height, which allowed the team to see how methane emissions were warping the icy surfaces of Arctic lakes.
NASA scientists conducted similar research using geospatial data as part of its Arctic Boreal Vulnerability Experiment.
A major source of Arctic methane is the organic material trapped with permafrost. As that permafrost melts, so too does the organic matter, which can be transformed into methane or carbon dioxide by microbes in the soil.
Low-oxygen, swampy areas are hotspots for methane, and scientists have documented streams of the gas seeping out of Arctic lakes formed by melting permafrost.
Engram’s team compared their own data to methane measurements taken on the ground at 48 lakes. Then they extrapolated the results to estimate emissions at 5,000 lakes across Alaska, Nature reported.
Their preliminary findings suggest that previous measurements have overestimated the amount of methane escaping large Arctic lakes. “Partly because scientists have spent more time studying smaller lakes with relatively high emissions,” Nature wrote.
At lakes in Alaska’s Barrow Peninsula, for example, the team’s estimates were 84 percent lower than other previous ones.
The study supports new techniques for detecting methane, but also provides more proof of climate change in the Arctic.
In other parts of this region, melting permafrost has caused the ground to literally bubble and opened the massive Batagaika crater in northeastern Siberia.
What’s more, the effect of methane is circuitous. More of it in the atmosphere could accelerate warming, which could in turn create even more permafrost lakes, and so on.
Methane is considered an extremely potent greenhouse gas, with a short-term warming impact 28 to 36 times more powerful than carbon dioxide. Human activity, such as fossil fuel production and agriculture, are currently responsible for 64 percent of Earth’s methane emissions.
One recent study looked at the consequences of the release of 50 gigatons of methane under the East Siberian Sea and estimated a cost of $60 trillion to the global economy.
