Thermokarst lakes are among the most dynamic features of the permafrost region. They form when ice-rich permafrost thaws and the ground subsides, creating depressions in which meltwater collects. Over years, decades and even millennia, these depressions grow into lakes. Paradoxically, the lakes then accelerate the very process that creates them: because liquid water conducts heat more effectively than frozen soil, a thermokarst lake drives further thawing beneath and around its basin. As the once-frozen organic carbon locked in the permafrost becomes accessible, microbes convert it into greenhouse gases such as carbon dioxide and methane, which can escape into the atmosphere. This feedback loop makes thermokarst lakes a key concern for scientists studying how Arctic carbon stores will respond to a warming climate, and it explains why the region’s lakes are not merely scenery but active players in the global climate system.

Dr Ingmar Nitze, a permafrost researcher at AWI in Potsdam, emphasises how much is at stake for the people who live in this landscape. ‘They are of great importance for local communities, as they are often the only source of drinking water,’ he says. The situation is complicated by the nature of the frozen ground itself: permafrost that in places extends several hundred metres below the surface acts as an impermeable barrier, preventing groundwater from being readily available. At the same time, surface waters can be heavily contaminated by pollutants, bacteria and industrial waste, meaning that communities frequently depend on a limited number of freshwater lakes. When one of those lakes suddenly drains away, the consequences for the local water supply can be immediate and severe.

The Lost Lakes platform addresses this problem by combining map views, time-series charts and satellite forecasts to display water levels across the Arctic in near real time. Users can examine spatial patterns, long-term trends and current satellite imagery for lakes in their own region or anywhere else in the permafrost zone. ‘Local people, who spend a lot of time in this landscape, are usually the first to notice its constant ongoing change,’ Nitze explains. ‘With Lost Lakes, they now also have access to real-time scientific data that support these personal observations, help them monitor the wider environment and may also enable them to plan necessary courses of action more effectively.’ The interactive dashboard is deliberately designed to be usable not just by researchers but by residents, hunters, herders and local authorities who need practical, up-to-date information about the waters they rely on.

The data assembled so far reveal a striking picture of recent change. Since 2016, just under 10,000 Arctic lakes have lost a sizeable proportion of their area or have disappeared entirely. The losses are not evenly distributed through the year. Most lakes drain suddenly shortly after snowmelt and up to the height of summer, between June and early August. Warm temperatures and snowy winters destabilise the permafrost, and the excess meltwater can carve lateral breaches along lake shores through which the entire water body escapes. A lake that may have existed for centuries can thus empty in a single event. The platform’s records show that an exceptionally large number of lakes disappeared in the summers of 2018, 2020 and 2022, years that followed extremely warm and snowy winters which preconditioned the ground for deeper summer thawing and subsequent lateral drainage.

Significant regional differences also emerge from the data, reflecting the strong dependence of lake dynamics on climate, subsoil and the condition of the permafrost itself. Western Alaska’s Seward Peninsula stands out as one of the most severely affected areas, where many of the largest lakes have vanished over roughly the past two decades. In the winter of 2017/2018 alone, 192 lakes on the peninsula drained completely or partially, almost twice as many as in the previous record years of 2005 and 2006. ‘North-western Alaska is heavily impacted by changing climate patterns, with new record highs for temperatures and precipitation recorded in recent years,’ Nitze notes. ‘This year, too, we have already observed a few notable lakes that are in the process of disappearing.’ The pattern suggests that as air temperatures and snowfall continue to climb, drainage events may become more frequent across ever larger parts of the Arctic.

Distinguishing a genuine, permanent lake drainage from a temporary dip in water level is one of the central technical challenges the AWI team had to solve. A lake can appear smaller in a satellite image for many benign reasons, including seasonal evaporation, ice cover or unusual viewing conditions. To make reliable statements from orbit, the researchers developed a numerical index calculated from satellite data that allows them to classify their observations. It is considered highly likely that a lake is losing water if it appears significantly smaller than expected in the imagery, or if its extent falls below the absolute minimum recorded since 2017. Beyond simple water surface area, the team analyses multispectral satellite images in ways that reveal surface water, snow and ice cover, exposed ground and vegetation, providing a much richer picture of what is happening around each lake.

‘With Lost Lakes, we can automatically and in near real time determine, for every lake in the Arctic permafrost region, whether sudden or gradual, persistent water losses are merely temporary anomalies or whether they are actually ushering in the permanent disappearance of a lake,’ Nitze explains. This capability turns what was once a laborious, region-by-region mapping exercise into a continuous, pan-Arctic monitoring system. For climate scientists, the resulting records offer a window into how rapidly permafrost landscapes are reorganising in response to warming. For communities on the ground, the same records function as an early warning system, flagging lakes at risk before the water is gone.

Lost Lakes did not appear in isolation. It forms part of the Permafrost Discovery Gateway, a freely accessible online platform that provides information on permafrost conditions across the Arctic, offering large spatial datasets and tools that local communities, researchers and the general public can use conveniently. Since 2023, an international group of experts including the AWI has been developing an artificial intelligence system for the gateway intended to make investigating Arctic permafrost thaw even faster and more effective. That effort, funded by Google.org to the tune of five million US dollars, embeds Lost Lakes within a broader infrastructure for Arctic observation and analysis.

Looking ahead, the AWI is also leading the Rapid Permafrost Thaw Carbon Trajectories project, known as PeTCaT, which continues and extends the analyses begun with Lost Lakes. PeTCaT aims to fill gaps in scientific understanding of rapid thaw processes and to build a novel dataset as a foundation for projections, highlighting potential future developments and the impact of greenhouse gases released from thawing permafrost. To achieve this, AWI is collaborating with researchers from Germany, the United States, Canada, the Netherlands and Sweden, with the project supported by a ten million US dollar fund from the non-profit organisation Schmidt Sciences. Together, these initiatives signal a shift in Arctic science: from periodic snapshots of a slowly changing landscape to a continuous, community-accessible watch over one of the planet’s most rapidly transforming environments, where lakes that sustained generations can vanish between one summer and the next.

Subject of Research: A satellite-based monitoring platform for detecting drainage and area changes of thermokarst lakes in Arctic permafrost regions

Article Title: Disappearing lakes: new data platform on permafrost lakes in the Arctic

Article References: Disappearing lakes: new data platform on permafrost lakes in the Arctic. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: permafrost, thermokarst lakes, Arctic, lake drainage, satellite monitoring, Alfred Wegener Institute, climate change, drinking water, Permafrost Discovery Gateway, PeTCaT, greenhouse gases, Alaska

PFAS are a large family of synthetic chemicals prized for their resistance to heat, water, oil and chemical degradation. Those same properties have made them extraordinarily persistent in the environment. Used in products ranging from stain-resistant fabrics and nonstick materials to firefighting foams, food packaging and industrial coatings, many PFAS can travel long distances through air and water before accumulating in soils, sediments, plants, animals and people. Because the carbon–fluorine bond is among the strongest in organic chemistry, these compounds are often described as “forever chemicals,” a term that captures their durability but also the growing concern over their movement through ecosystems.

Permafrost is ground that remains frozen for at least two consecutive years, although vast areas of the Arctic have stayed frozen for centuries or even millennia. It is not a chemically inert block of ice. Permafrost contains mineral particles, organic matter, ancient water, microbial communities and pollutants deposited from the atmosphere or transported from distant regions. As temperatures rise, the active layer—the upper portion of soil that freezes and thaws seasonally—deepens. Thaw can also create thermokarst landscapes, slumping riverbanks, expanding ponds and new drainage pathways. Each of these changes can expose previously frozen material to liquid water and increase the possibility that contaminants will be carried into streams, lakes and wetlands.

The study focuses on perfluoroalkyl substances reaching surface waters, a pathway that is particularly important because rivers, ponds and shallow lakes connect terrestrial environments to food webs and human communities. When PFAS are released from thawing soils, they may dissolve in water, attach to suspended particles or accumulate in sediments before being transported downstream. Their behavior depends on molecular structure, soil chemistry, temperature, water flow and the amount of organic matter present. Some compounds are highly mobile and can move rapidly with water, while others are more strongly retained by soils or sediments. A warming climate can alter all of these controls at once, making contaminant transport less predictable and potentially more widespread.

The projected increase does not necessarily mean that every Arctic water body will experience the same rise in PFAS concentrations. Local conditions can determine whether chemicals are trapped in sediment, diluted by rainfall, concentrated during evaporation or flushed rapidly through a watershed. Seasonal pulses may also become more important than annual averages. Spring snowmelt, intense rainfall and sudden thaw events can produce short-lived surges of water that mobilize contaminants from exposed ground. Such pulses may be difficult to detect with occasional sampling, yet they can deliver chemicals to aquatic organisms at critical moments in their life cycles.

The implications extend beyond chemistry and hydrology. PFAS can persist in organisms and move through aquatic food webs, raising concerns for fish, migratory birds and mammals that depend on northern waters. Some compounds have been associated in toxicological and epidemiological research with immune-system effects, altered lipid metabolism, developmental impacts and other health concerns, although the risks vary widely across individual substances and exposure levels. The study’s projection therefore points to a climate-linked contaminant pathway rather than a single, uniform threat. It suggests that environmental monitoring in cold regions must account for chemicals released from the landscape itself, not only pollutants arriving through current industrial activity or atmospheric transport.

The research also highlights why permafrost thaw is increasingly viewed as a multiplier of environmental change. Warming can destabilize the physical structure of frozen terrain, transform drainage networks and accelerate the breakdown of organic material. At the same time, it can reactivate contaminants that were deposited when historical emissions were higher or when industrial compounds traveled north through the atmosphere. PFAS are especially concerning in this context because their persistence means that a delay between deposition and release does not eliminate the hazard. Instead, frozen ground may function as a temporary reservoir, postponing the movement of chemicals until climate conditions open new routes into surface waters.

For scientists and policymakers, the findings point toward a need for integrated surveillance across the Arctic and other permafrost regions. Chemical measurements should be paired with observations of soil temperature, thaw depth, hydrology, erosion and extreme-weather events. Monitoring programs will need to distinguish between older, long-chain PFAS and newer replacement compounds, because their mobility and environmental behavior can differ. The most informative studies will likely combine field sampling with watershed models capable of representing changing freeze–thaw cycles and sudden landscape disturbances. Without that integration, gradual contamination may be mistaken for isolated events, and brief but important transport pulses may go unnoticed.

The projected rise in PFAS release is a reminder that global warming can unlock more than carbon from frozen ground. It can mobilize a chemical inheritance created by modern society and deliver it into ecosystems that are already under pressure from rising temperatures, shrinking sea ice, altered vegetation and changing wildlife patterns. The study by Yu and colleagues does not present warming as a distant threat confined to climate statistics; it describes a mechanism through which atmospheric change can directly reshape the movement of persistent pollutants. As permafrost continues to thaw, the Arctic may become not only a visible front line of climate change, but also a source of contaminants whose environmental journey is only beginning.

Subject of Research: Perfluoroalkyl substance release from permafrost into surface waters under global warming.

Article Title: Perfluoroalkyl substance release in permafrost surface waters is projected to increase under global warming.

Article References: Yu, H., Wang, X., Wang, C. et al. Perfluoroalkyl substance release in permafrost surface waters is projected to increase under global warming. Commun Earth Environ (2026). https://doi.org/10.1038/s43247-026-03946-6

Image Credits: AI Generated

DOI: 10.1038/s43247-026-03946-6

Keywords: PFAS, perfluoroalkyl substances, forever chemicals, permafrost thaw, global warming, Arctic surface waters, climate change, environmental contamination, pollutant transport