A glacial river during the Arctic winter forms proglacial icing. Image credit: Gabrielle Kleber
Arctic glaciers, rapidly shrinking due to climate change, are revealing active groundwater springs, which are seen to emit substantial amounts of methane—a strong greenhouse gas. As reported in the journal Nature Geoscience, these emissions are projected to rise as global warming causes further glacier recession. These methane sources, hitherto unaccounted for in methane budget calculations, present an additional and expanding threat.
Research published on July 6th in Nature Geoscience, suggests that as the Arctic continues to heat up, the receding glaciers are laying bare groundwater springs that could be an underappreciated methane source. The study, carried out by teams from the University of Cambridge and the University Centre in Svalbard, Norway, identified significant quantities of methane gas escaping from groundwater springs exposed by melting glaciers.
The researchers predict that methane emissions from these springs will likely increase as more springs are revealed with the retreat of Arctic glaciers, potentially intensifying global warming. This, along with other methane releases from melting Arctic ice and permafrost, presents a mounting challenge.
“Until now, our estimates of the global methane budget have overlooked these springs, which represent a substantial and possibly growing source of methane emissions,” stated Gabrielle Kleber, the lead author of the study and a researcher from Cambridge’s Department of Earth Sciences.
Scientists worry that additional methane released from the thawing Arctic could accelerate anthropogenic global warming. The springs examined in this study were previously unidentified as a potential methane source.
For nearly three years, Kleber monitored the water chemistry of over a hundred springs in Svalbard, where temperatures are rising twice as fast as the Arctic average. Drawing a parallel to the “canary in the coal mine” adage, Kleber describes Svalbard as an early warning of potential large-scale methane release across the region due to its accelerated warming.
Professor Andrew Hodson, a co-author of the study from the University Centre in Svalbard, describes living in Svalbard as being on the front lines of Arctic climate change. The sight of methane venting in the immediate vicinity of a retreating glacier is a stark reminder of this reality.
Prior research has mainly focused on methane emissions from thawing permafrost. “This new finding shows that there are additional pathways for methane release that could have an even greater impact on the global methane budget,” added study co-author Professor Alexandra Turchyn, also from the Cambridge’s Department of Earth Sciences.
Hodson further noted that prior to this study, the source and pathways of this methane were unclear due to a focus on regions in the Arctic where glaciers do not exist.
The springs that deliver methane are connected to an underground plumbing system beneath most glaciers, which taps into large groundwater reservoirs within the underlying sediments and surrounding bedrock. Once the glaciers melt and retreat, these groundwater networks surface as springs.
The team discovered that the methane emissions from glacial groundwater springs across Svalbard could surpass 2,000 tonnes in a year — roughly equivalent to 10% of the methane emissions from Norway’s annual oil and gas energy sector.
Kleber trained herself to identify these springs from satellite imagery, focusing on areas exposed by the retreat of 78 glaciers across Svalbard. She sought blue ice patches—indicative of groundwater leakage—and physically visited these sites to take groundwater samples.
Chemical profiling of the spring water revealed that nearly all the sites were laden with dissolved methane. As a result, a significant amount of methane can escape into the atmosphere when the spring water surfaces.
The team also found that methane emission hotspots were closely linked to the type of rock from which the groundwater emerges. Certain rocks like shale and coal contain natural gases, including methane, produced by organic matter decomposition.
“We’re beginning to understand the complex and cascading impacts triggered by glacier melt in Svalbard,” said Kleber, “and it’s likely that we will discover more consequences like this.”
“The amount of methane leaking from the springs we measured is likely just a fraction of the total volume of trapped gas below these glaciers, waiting to escape,” warned Hodson, “We urgently need to assess the risk of a sudden increase in methane leakage, as glaciers will only continue to retreat as we struggle to manage climate change.”
Citation: “Groundwater springs formed during glacial retreat are a large source of methane in the high Arctic” by Gabrielle E. Kleber, Andrew J. Hodson, Leonard Magerl, Erik Schytt Mannerfelt, Harold J. Bradbury, Yizhu Zhu, Mark Trimmer and Alexandra V. Turchyn, 6 July 2023, Nature Geoscience.
DOI: 10.1038/s41561-023-01210-6
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Frequently Asked Questions (FAQs) about Arctic methane emissions
What is the main finding of the study regarding Arctic glaciers and methane emissions?
The main finding of the study is that melting Arctic glaciers are uncovering groundwater springs that release significant amounts of methane, a potent greenhouse gas. This methane source was previously unrecognized in methane budget estimations and is expected to increase as glaciers continue to retreat.
How are shrinking Arctic glaciers contributing to methane emissions?
Shrinking Arctic glaciers are exposing groundwater springs that contain methane. As these springs are revealed due to glacier melting, the methane trapped in the groundwater is released into the atmosphere, contributing to methane emissions. With further glacier recession, more springs are expected to be exposed, intensifying methane emissions.
Why are scientists concerned about methane emissions from Arctic thaw?
Scientists are concerned about methane emissions from Arctic thaw because methane is a potent greenhouse gas. Additional methane released by the Arctic thaw can accelerate global warming and contribute to climate change. The newly discovered methane emissions from groundwater springs add to the existing concern of methane releases from melting ice and permafrost in the Arctic.
What are the implications of the study’s findings for the global methane budget?
The study’s findings suggest that the methane emissions from groundwater springs in Arctic glaciers were not previously accounted for in global methane budget estimations. These emissions, which are expected to increase as glaciers retreat, represent a significant and potentially growing source of methane. Understanding and including these emissions in future methane budget calculations is crucial for accurately assessing and addressing climate change impacts.
More about Arctic methane emissions
- Nature Geoscience: Groundwater springs formed during glacial retreat are a large source of methane in the high Arctic
- University of Cambridge: Arctic’s melting glaciers reveal hidden methane time bomb
- University Centre in Svalbard: Melting glaciers reveal a potent, previously overlooked methane source
- ScienceDaily: Melting Arctic glaciers could unleash unaccounted methane into atmosphere
