PLANET EARTH
Deep beneath the permafrost that blankets a group of islands in the Arctic Ocean lurks a growing and migrating sea of methane. The thick permafrost, or ground that remains frozen for at least two years, forms a tight seal that has so far prevented millions of cubic metres of methane from wafting out, but there’s no guarantee that the potent greenhouse gas won’t eventually escape. “At present, the leakage from below permafrost is very low, but factors such as glacial retreat and permafrost thawing may ‘lift the lid’ on this in the future,” said Thomas Birchall, a geologist at the University Center in Svalbard in Norway.
The base of permafrost is undulating, which creates pockets between the permafrost and the underlying geology where gas from biological and non-biological sources can accumulate and become trapped. Should this permafrost seal disintegrate, it could set off a chain reaction in which the methane’s strong warming effect would thaw more permafrost and release even more gas. This vicious feedback loop would further accelerate warming, melting and methane emissions.
Permafrost is widespread on Svalbard, a Norwegian archipelago located deep inside the Arctic Circle and just 500 miles from the North Pole. Missions that involve drilling into the frozen soil in search of fossil fuels often hit pockets of natural gas by accident, but the extent of these reserves was unknown. Birchall and his colleagues used historical data from commercial and scientific boreholes to map the permafrost throughout Svalbard and pinpoint these stores of natural gas. The researchers found deposits rich in methane are much more common than thought on the islands. Given that the archipelago has a s
