Arctic coastlines threatened by melting permafrost
SVALBARD: As the planet warms, the perpetually frozen soil known as permafrost that covers Alaska, Siberia and other parts of the Northern Hemisphere is slowly melting away.
Scientists are monitoring this with a growing sense of alarm because permafrost contains roughly 1.7 trillion tons of organic carbon dioxide from decayed plant debris trapped in the soil. Recent studies have found that carbon and methane released from permafrost could equal 40 percent of annual greenhouse gas emissions.
But melting permafrost also poses a much more immediate risk, one that is often overlooked by climatologists grappling with the potential emissions problem.
Approximately 34 percent of the world’s coastlines are covered in permafrost, which absorbs the impact of ocean waves and protects against coastal erosion. Sea ice helps too, by blocking waves from reaching the shore.
That buffer zone is disappearing, however, and without it coastal erosion could accelerate and threaten critical infrastructure – including oil and gas pipelines – in the Arctic and elsewhere, according to Aleksey Marchenko, a scientist studying the issue at the University Center in Svalbard.
“The main mechanism for coastal erosion [in the Arctic] is the melting of permafrost and increased storm activity,” said Marchenko, an expert in ice mechanics from Moscow.
Last year, Marchenko set up a custom-built sensor off the coast of Longyearbyen on Svalbard – an archipelago midway between Norway and the North Pole – to model the rate of coastal erosion in the region.
After waiting 12 months, Marchenko and his team of researchers recently fished the sensor out of the sea and took it back to the university lab for analysis.
Marchenko is still sifting through data. But he said he now believes the melting of permafrost plays a much larger role in hastening coastal erosion on Svalbard than initially believed.
More information needs to be gathered. It’s unclear, for instance, why permafrost melts faster in some places than others, and the rate of erosion on Svalbard remains unknown, according to a 2013 study by the Institute for Polar and Marine Research in Potsdam, Germany.
“The melting is inconsistent,” Marchenko said. “In one place it might be melting quickly, in another less quickly.”
Still, the findings could inform future development projects in Longyearbyen, where planners have proposed a new harbor near the town’s airport.
If the once-sturdy shoreline is susceptible to erosion, the design of the harbor and other planned waterfront infrastructure might have to be strengthened, Marchenko said, in order to account for the changing landscape.
And the implications for the oil and gas industry could be even more costly in regions where pipelines connected to offshore wells are buried in shoreline permafrost. Erosion activity fueled by permafrost melt could disturb the pipelines and even cause underground leaks, Marchenko said.
“Permafrost is very important for the structure of coastal zones,” said Marchenko. If permafrost coasts continue eroding, “it could create some catastrophic events.”