Climate change has exposed a new source of methane in the Arctic: groundwater springs. As global warming drives glaciers to retreat, methane-rich groundwater springs are punching through the surface in the Arctic, the study published in the journal Nature Geoscience stated.
Methane, a greenhouse gas, is 84 times more potent than carbon dioxide on a 20-year timescale.
In Svalbard, a Norwegian archipelago in the Arctic, groundwater springs could be emitting more than 2,000 tonnes of methane annually. This figure, the paper explained, equals 10 per cent of the methane emissions from Norway’s annual oil and gas energy industry.
“Since it [Svalbard] is warming faster than the rest of the Arctic, we can get a preview of the potential methane release that could happen at a larger scale across this region,” Gabrielle Kleber, lead author and a researcher from Department of Earth Sciences, University of Cambridge, said in a statement.
These springs are not part of the global methane budget. The global methane budget estimates the amount of methane released through sources and captured through sinks.
Using satellite images, researchers from Europe and Canada spotted groundwater springs exposed by 78 retreating glaciers in Svalbard. Next, they analysed the water chemistry of more than a hundred springs spotted across Svalbard.
The water in all but one site had high levels of dissolved methane, which escapes into the atmosphere. Further, these springs emit this greenhouse gas year-round, the researchers noted.
“If global warming continues unchecked, methane released from glacial groundwater springs will probably become more extensive,” Kleber warned.
The rocks are most likely regulating the springs’ emissions. For example, areas where groundwater emerged from shale rocks were found to be methane hotspots.
High methane concentrations near shale rocks suggested a geologic or thermogenic (heat) source of gas, which moves upwards through fractures in the rocks and gathers under the glacier. A lot more methane gas could be trapped under glaciers, waiting to escape, the researchers explained.
“That means we urgently need to establish the risk of a sudden increase in methane leakage because glaciers will only continue to retreat while we struggle to curb climate change,” Andrew Hodson, study co-author from the University Centre in Svalbard, noted.
Going forward, the team suggests that an improved understanding of possible pan-Arctic methane release from groundwater springs is necessary.
This, they wrote, will help assess the importance of such emissions and their potential global climate impact.
“This is particularly relevant in regions where glaciers are capping large reservoirs of geologic methane, such as parts of Arctic Canada and the Russian Arctic, where further melting of the cryosphere could lead to considerable seeps of this potent greenhouse gas,” the paper said.