Arctic sea ice is melting at a much faster rate than previously expected. A new study warns that within just two and a half years, the Arctic Ocean could experience its first nearly ice-free summer—a dramatic milestone in the unfolding climate crisis.
For as long as humans have known the Arctic Ocean, it has remained ice-covered—even at the height of summer. But due to accelerating climate change, the first nearly ice-free Arctic summer is now expected much sooner than previously thought. At some point, there will no longer be enough ice in the Arctic Ocean to serve as a significant cooling factor, and a new study warns that this tipping point could arrive as early as 2027 under the most extreme scenario. The study estimates that the highest probability for this event falls within 7 to 20 years, though some models suggest a much later date. Taking all projections into account, the median estimate suggests that the first ice-free summer day will occur within the next 24 years.
The first Arctic summer with nearly ice-free conditions in the Arctic Ocean may arrive much sooner than previously thought. Satellite image of the Arctic Ocean and its ice cover in summer 2024. Yellow line shows the median ice extent from 1981 to 2010 | NOAA, NSIDC
When The Ice Runs Out
An “ice-free day” is defined as a day when the total sea ice area in the Arctic Ocean drops below 1 million square kilometers - a threshold below which, according to current estimates, the ice is no longer considered sufficient to provide significant cooling to the Arctic region. For comparison, even during the hottest period last year, Arctic sea ice still covered approximately 3.4 million square kilometers. A 2023 study, along with similar earlier research studies, projected that the disappearance of Arctic ice would be a much more gradual process, with no ice-free day expected before the end of the 21st century. The new study, however, presents a far more alarming forecast.
The researchers, based in the U.S. and Sweden, used advanced climate models from the CMIP6 climate research project, the latest phase of the Coupled Model Intercomparison Project. This initiative features next-generation climate simulations designed to improve the predictive accuracy of climate models used to forecast climate change. The tools it provides assists governments and international bodies in assessing the potential impacts of climate change and global warming and in designing appropriate environmental policies. CMIP6 simulations require immense computational power, as they incorporate large volumes of observational data and climate projections.
Unlike previous studies that relied on monthly projections, this new research analyzed daily weather data to produce the most accurate possible prediction for the first ice-free Arctic day. The scientists used 11 models that showed strong alignment with historical climate data and generated 366 separate projections to explore a wide range of climate scenarios. The CMIP6 framework was used to estimate, as precisely as possible, the effects of natural climate variability, greenhouse gas emissions, and the complex interactions between ocean and atmospheric warming.
The researchers generated 366 different projections to explore a wide range of climate scenarios. The graph shows the percentage of models predicting a sea ice-free day within a given number of years. Colors represent different carbon emission scenarios: low emissions (blue), high emissions (yellow) | From Heuzé, C., et al., Nat Commun 2024
A Nightmare Scenario
Simulations suggest that an ice-free Arctic day could be triggered by a sequence of extreme weather events in the Arctic. The chain reaction would begin with an unusually warm autumn, which would weaken the ice layer. This would be followed by an abnormally mild winter and spring, preventing ice from regenerating, and culminating in a particularly hot summer with storms that would melt the remaining ice.
In fact, we are already witnessing signs of these warming trends: In March 2022, temperatures in the Arctic Circle were 10°C above the multi-year average for that time of year, which could provide an ominous glimpse of what lies ahead.
The bright, reflective surface of Arctic sea ice acts as a natural mirror, reflecting solar radiation back into space and helping to regulate global temperatures. But as the ice-covered area shrinks, larger portions of the dark ocean surface become exposed, absorbing more heat instead of reflecting it. This leads to increased warming and a faster melting process. The result is a positive feedback loop, in which each stage of warming amplifies the next. These changes may disrupt wind patterns, alter ocean currents, and increase the frequency of extreme weather events around the globe—especially in the Northern Hemisphere.
A single ice-free day may not immediately trigger a global climate shift, but it would still mark a dramatic turning point. According to climate researcher Alexandra Jahn from the University of Colorado Boulder, one of the study’s authors, such an event would signal that we have fundamentally altered one of the Arctic’s key features: the permanent, year-round snow and ice cover.
The researchers emphasize that drastic reductions in greenhouse gas emissions could delay the timeline and reduce the duration of ice-free conditions in the Arctic Ocean. “Any reduction in emissions would help preserve sea ice,” says Jahn.
But will humanity act before it’s too late? The year 2024 has already marked a troubling milestone: for the first time, the global average temperature has exceeded 1.5°C above pre-industrial levels (1850–1900). This threshold was defined as a red line in the Paris Agreement, intended to mobilize global cooperation to prevent the most severe ecological and human impacts of climate change. Now, it appears we have already crossed it.
If immediate action is not taken, we may find ourselves on an irreversible path, where the Arctic ice that has served as Earth's natural cooling system for thousands of years will become nothing more than a distant memory.