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What we know about marine heatwaves in the Arctic
19. June 2026
A new study by the AWI shows that marine heatwaves have been taking a greater toll on the Arctic Ocean in recent decades and that there is an urgent need for further research
In recent years, marine heatwaves have been taking an ever-greater toll on the world’s oceans and their ecosystems. Amplified by increasing global warming, these events are occurring more frequently and lasting longer. The Arctic is not spared from this trend either, as it is warming faster than any other region on our planet. However, due to local processes and conditions, marine heatwaves in the Arctic differ fundamentally from those in non-polar oceans. A recent study, led by the Alfred Wegener Institute, in the journal Communications Earth & Environment, summarizes how these events have developed over recent decades, what science knows about the driving forces behind them, and where there are still knowledge gaps to be filled.
Marine heatwaves are individual extreme events in which sea temperatures are unusually high for at least five days. They occur when strong solar radiation or warm air heats the water or when ocean currents carry unusually warm water in. “Recent studies show that the number of marine heatwaves has also increased significantly in the Arctic over the past few decades,” says Dr Marylou Athanase of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). In a new publication, the climate researcher has summarized the current state of scientific knowledge, which highlights just how little these heat events are researched. Whilst research into marine heatwaves has seen a surge worldwide in recent years, studies in the Arctic remain scarce and there is no comprehensive assessment of their characteristics, drivers and impacts, or how these factors interact. “Yet in the Arctic, even a temporary rise in temperature of a fraction of a degree can have cascading impacts on the heat-sensitive polar ecosystem, and possible implications for the global climate system,” says Marylou Athanase.
The available data show that the duration, intensity and frequency of marine heatwaves in the Arctic have increased significantly since the 1980s. During such extreme events, sea surface temperatures can be up to 4 degrees Celsius above the seasonal average. “The marginal seas of the Arctic are consistently emerging as hotspots,” explains Marylou Athanase. “Here, surface heatwaves are becoming up to 0.6 degrees hotter per decade and occur about twice as frequently as the global average. Estimates across all Arctic sectors range from 1 to 3 events per year.” Deeper below the surface, between 50 and 500 meters, heatwaves are similar or even more intense. On the seabed, however, they show hardly any increase in frequency or intensity; in some regions, there is even a decrease. Above all, the duration of marine heatwaves in the Arctic is increasing faster than anywhere else in the world, ranging from around 10 to 40 days depending on the region. The longest event on records occurred in the Barents Sea in 2016: for over 480 days, temperatures at the surface and on the seabed were a good 1 degree Celsius above average.
What drives marine heatwaves in the Arctic
In the Arctic, there are climate processes that have no equivalent at lower latitudes: the presence of sea ice, altering heat fluxes between the atmosphere and the ocean, and the injection of ocean heat stored deep below the Arctic surface represent a previously overlooked class of influencing factors. “Two interlinked mechanisms in particular are driving the increase in marine heatwaves: the general warming of the ocean and the decline in sea ice,” says Marylou Athanase. “Heat input from the atmosphere to the ocean in the Arctic depends largely on sea ice. When it melts in summer, the sea surface can absorb more solar radiation, which in turn intensifies warming via the ice-albedo feedback.” For example, during the marine heatwaves of 2007 and 2020, the Arctic Ocean absorbed almost twice as much solar energy as is usual in summer due to the extremely low sea ice cover.
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Athanase, M., Gou, R., Köhn, E.E. et al. Polar processes set Arctic marine heatwaves apart. Commun Earth Environ 7, 485 (2026). https://doi.org/10.1038/s43247-026-03735-1A new study by the AWI shows that marine heatwaves have been taking a greater toll on the Arctic Ocean in recent decades and that there is an urgent need for further research
In recent years, marine heatwaves have been taking an ever-greater toll on the world’s oceans and their ecosystems. Amplified by increasing global warming, these events are occurring more frequently and lasting longer. The Arctic is not spared from this trend either, as it is warming faster than any other region on our planet. However, due to local processes and conditions, marine heatwaves in the Arctic differ fundamentally from those in non-polar oceans. A recent study, led by the Alfred Wegener Institute, in the journal Communications Earth & Environment, summarizes how these events have developed over recent decades, what science knows about the driving forces behind them, and where there are still knowledge gaps to be filled.
Marine heatwaves are individual extreme events in which sea temperatures are unusually high for at least five days. They occur when strong solar radiation or warm air heats the water or when ocean currents carry unusually warm water in. “Recent studies show that the number of marine heatwaves has also increased significantly in the Arctic over the past few decades,” says Dr Marylou Athanase of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). In a new publication, the climate researcher has summarized the current state of scientific knowledge, which highlights just how little these heat events are researched. Whilst research into marine heatwaves has seen a surge worldwide in recent years, studies in the Arctic remain scarce and there is no comprehensive assessment of their characteristics, drivers and impacts, or how these factors interact. “Yet in the Arctic, even a temporary rise in temperature of a fraction of a degree can have cascading impacts on the heat-sensitive polar ecosystem, and possible implications for the global climate system,” says Marylou Athanase.
The available data show that the duration, intensity and frequency of marine heatwaves in the Arctic have increased significantly since the 1980s. During such extreme events, sea surface temperatures can be up to 4 degrees Celsius above the seasonal average. “The marginal seas of the Arctic are consistently emerging as hotspots,” explains Marylou Athanase. “Here, surface heatwaves are becoming up to 0.6 degrees hotter per decade and occur about twice as frequently as the global average. Estimates across all Arctic sectors range from 1 to 3 events per year.” Deeper below the surface, between 50 and 500 meters, heatwaves are similar or even more intense. On the seabed, however, they show hardly any increase in frequency or intensity; in some regions, there is even a decrease. Above all, the duration of marine heatwaves in the Arctic is increasing faster than anywhere else in the world, ranging from around 10 to 40 days depending on the region. The longest event on records occurred in the Barents Sea in 2016: for over 480 days, temperatures at the surface and on the seabed were a good 1 degree Celsius above average.
What drives marine heatwaves in the Arctic
In the Arctic, there are climate processes that have no equivalent at lower latitudes: the presence of sea ice, altering heat fluxes between the atmosphere and the ocean, and the injection of ocean heat stored deep below the Arctic surface represent a previously overlooked class of influencing factors. “Two interlinked mechanisms in particular are driving the increase in marine heatwaves: the general warming of the ocean and the decline in sea ice,” says Marylou Athanase. “Heat input from the atmosphere to the ocean in the Arctic depends largely on sea ice. When it melts in summer, the sea surface can absorb more solar radiation, which in turn intensifies warming via the ice-albedo feedback.” For example, during the marine heatwaves of 2007 and 2020, the Arctic Ocean absorbed almost twice as much solar energy as is usual in summer due to the extremely low sea ice cover.
…