A growing body of peer-reviewed research points to an enormous reservoir of methane locked beneath Arctic permafrost and shallow ocean sediments, one that scientists say could accelerate global warming far beyond current projections if even a small portion escapes. The warning centers on the East Siberian Arctic Shelf, where field observations have documented widespread methane venting from the seafloor into waters already saturated with the gas. With recent data showing parts of the Arctic tundra flipping from a net absorber of carbon to a net emitter, the question is no longer whether this methane will reach the atmosphere but how fast and how much.
Thousands of Observations Reveal a Leaking Seafloor
The scale of the problem first came into sharp focus through a study led by Natalia Shakhova and colleagues in Science, which compiled thousands of field measurements showing widespread methane supersaturation in East Siberian Arctic Shelf waters. The data revealed that methane was not confined to isolated seeps but was escaping across broad stretches of the shallow continental shelf, where degrading subsea permafrost no longer forms a reliable cap. The researchers warned that remobilization of only a small fraction of the methane stored in these shallow deposits could trigger abrupt warming, a finding that remains one of the most cited risk assessments in Arctic climate science and a touchstone for debates over so‑called “methane time bomb” scenarios.
Subsequent isotopic analysis has sharpened the picture of where this gas originates and how it moves through the water column. A study in the Proceedings of the National Academy of Sciences measured high dissolved methane in Laptev Sea waters and used multiple isotope systems, including radiocarbon dating, to determine that much of the methane escaping from active seep zones is old and likely thermogenic, generated deep underground over geological timescales rather than produced recently by microbes near the surface. The same research found evidence of microbial oxidation consuming some methane in waters farther from seeps, a natural brake that limits how much gas reaches the air. Yet the oxidation capacity of cold Arctic waters is finite, and scientists remain uncertain whether it can keep pace with accelerating releases as sea ice retreats, bottom waters warm, and permafrost continues to degrade.
How Large Is the Carbon Pool at Stake
Quantifying the total carbon locked in circumpolar permafrost is essential for understanding the upper bound of risk, both on land and beneath the ocean. A 2014 study in Biogeosciences produced detailed maps and profiles of permafrost soil organic carbon stocks, with uncertainty ranges and depth stratification for the top three meters of soil, plus deeper deposits in Yedoma regions and Arctic river deltas. These estimates place the total carbon pool in the range of roughly 1,300 to 1,700 gigatons when deeper formations are included, a store that dwarfs the carbon currently held in the entire atmosphere. Much of this carbon is still frozen, but as thaw progresses, microbes can convert part of it into carbon dioxide and methane, adding new greenhouse gases on top of human emissions.
The sheer volume helps explain why even fractional releases carry outsized consequences. An analysis summarized by Yale Environment 360 noted that should the full subsea permafrost layer thaw, an amount of methane potentially equal to many times the current atmospheric burden could be mobilized, though this represents a worst‑case scenario rather than a near‑term forecast. Methane is roughly 80 times more potent than carbon dioxide as a greenhouse gas over a 20‑year window, so even modest additions to the atmosphere carry disproportionate warming power. This is why researchers treat Arctic methane as a high‑consequence risk: the probability of an abrupt, catastrophic release may be debated, but the impacts of sustained, incremental emissions are large enough to influence global temperature trajectories and complicate efforts to meet international climate targets.
Tundra Flips from Carbon Sink to Source
Field monitoring is already showing that the Arctic carbon balance is shifting in ways that validate long‑standing model concerns. According to the latest Arctic assessment from NOAA, the tundra has effectively transitioned from a carbon sink to a carbon source when wildfire emissions are included, and the region remains a consistent methane emitter year‑round. That transition matters because it means the Arctic is no longer simply storing carbon; it is actively adding greenhouse gases to the atmosphere, creating a feedback loop in which warming begets more thaw, more fire, and more emissions. Independent work reported by The Guardian has similarly found that a substantial portion of the Arctic’s historical carbon sink is now a net source, reinforcing the NOAA findings with separate datasets and methods.
This observed shift sits in tension with the most recent consensus assessment from the Intergovernmental Panel on Climate Change. In its latest physical science report, the IPCC Working Group I assessed projected carbon dioxide release from permafrost per degree of warming and concluded it is “very unlikely” that terrestrial and subsea permafrost combined will become a net source of greenhouse gas emissions large enough to dominate the global budget this century. At the same time, the report acknowledged low confidence in the magnitude of those projections because models still do not fully capture abrupt thaw processes, thermokarst lake formation, deep subsidence, and subsea destabilization. The gap between what models predict and what field stations now measure is one of the most consequential uncertainties in climate science, influencing both mitigation planning and assessments of how much warming is already locked in.
Global Methane Budget Puts Arctic Seeps in Context
To understand how Arctic emissions fit into the bigger picture, scientists turn to the Global Methane Budget, which synthesizes atmospheric measurements, inventories, and model outputs into a unified account of sources and sinks. The most recent update from the Global Carbon Project, published in Earth System Science Data, provides a detailed breakdown of methane emissions between 2000 and 2020 from natural systems such as wetlands, freshwater bodies, and geological seeps, alongside emissions from agriculture, fossil fuels, and waste. Geological sources, which include the kind of thermogenic seeps observed on the East Siberian Arctic Shelf, are estimated to be much smaller than emissions from human activities, but they are also less well constrained and harder to manage. Because atmospheric methane concentrations are rising faster than many models anticipated, researchers are scrutinizing these natural high‑latitude sources to determine how much of the recent growth they can explain.
Within this global budget, Arctic permafrost and shelf emissions currently appear as a modest fraction of total methane, but their trajectory is what alarms scientists. As warming accelerates, wetlands expand, seasonal thaw deepens, and coastal erosion exposes ancient carbon, creating new pathways for methane to escape. The Global Methane Budget emphasizes that uncertainties around high‑latitude sources remain large, meaning today’s relatively small contribution could grow substantially in coming decades. This is why monitoring networks are being expanded across Siberia, Alaska, and the Canadian Arctic, combining satellite data, aircraft campaigns, and in situ measurements to track changes in real time and feed more realistic behavior into climate models.
What Rising Arctic Methane Means for Climate Policy
The emerging picture from seafloor surveys, tundra flux towers, and atmospheric measurements points toward a steadily weakening Arctic carbon buffer at the same time human emissions remain high. Observations synthesized in NOAA’s recent Arctic climate update show rapid warming, shrinking sea ice, and intensifying wildfire seasons, all of which interact with permafrost to hasten greenhouse gas releases. Rather than a single tipping point, scientists increasingly describe a series of overlapping thresholds: once crossed, they make it progressively harder to stabilize temperatures because natural feedbacks begin to amplify human‑driven warming. In this context, every additional decade of elevated fossil fuel use not only raises temperatures directly but also increases the likelihood that Arctic carbon stores will shift irreversibly from long‑term sinks to long‑term sources.
For policymakers, the implications are twofold. First, aggressive cuts to methane and carbon dioxide emissions remain the most effective lever for limiting how much Arctic permafrost thaws in the first place, reducing the size of the feedback that future generations will have to manage. Second, planning for climate impacts must account for the possibility that natural emissions will erode part of the carbon budget assumed in mitigation pathways, particularly those that rely on tight temperature limits such as 1.5°C. The science emerging from the East Siberian Arctic Shelf, the circumpolar permafrost belt, and the global methane budget does not guarantee an imminent “methane catastrophe,” but it does underscore that the window for avoiding self‑reinforcing Arctic warming is narrowing, and that decisions taken in the next few years will strongly influence how much of this vast frozen carbon pool ultimately stays in the ground.
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*This article was researched with the help of AI, with human editors creating the final content.
