The first summer with nearly no Arctic sea ice could occur as early as 2027, according to an international team of researchers. This milestone was predicted using advanced computer models by scientists including CU Boulder climatologist Alexandra Jahn and Céline Heuzé from the University of Gothenburg, Sweden.
Arctic sea ice is melting as a result of climate change. Image Credit: Céline Heuzé/University of Gothenburg
For this study, the researchers used advanced computer models to estimate when the Arctic might experience its first ice-free day. This dramatic change could disrupt ecosystems and alter global weather patterns.
The first ice-free day in the Arctic won’t change things dramatically. But it will show that we've fundamentally altered one of the defining characteristics of the natural environment in the Arctic Ocean, which is that it is covered by sea ice and snow year-round, through greenhouse gas emissions.
Alexandra Jahn, Associate Professor, Department of Atmospheric and Oceanic Sciences Institute of Arctic and Alpine Research, University of Colorado Boulder
A Blue Arctic
As global temperatures rise due to increasing greenhouse gas emissions, Arctic sea ice has been disappearing at an unprecedented rate of over 12 % per decade.
In September, the National Snow and Ice Data Center revealed that this year’s Arctic sea ice minimum—the day with the least frozen seawater—was among the lowest recorded since 1978. Measuring 1.65 million square miles (4.28 million square kilometers), it exceeded the record low observed in September 2012 but remains a stark contrast to the 1979–1992 average of 6.85 million square kilometers.
The Arctic is considered "ice-free" when its sea ice coverage falls below 1 million square kilometers. While past research has focused on when the region might experience an entire month without sea ice, projections suggest this could occur by the 2030s.
As the tipping point approaches, the research team has been interested in finding out when the first summer day that melts virtually all of the Arctic sea ice will occur.
Because the first ice-free day is likely to happen earlier than the first ice-free month, we want to be prepared. It’s also important to know what events could lead to the melting of all sea ice in the Arctic Ocean.
Céline Heuzé, University of Gothenburg
Non-Zero Possibility
Jahn and Heuzé used data from over 300 computer simulations to estimate when the first ice-free day in the Arctic might occur. Their findings indicate that, regardless of changes in human greenhouse gas emissions, the first ice-free day could happen within nine to 20 years after 2023. In an extreme scenario, the earliest occurrence of this milestone could be within just three years.
Although such a scenario is less likely, the models show it remains a possibility. Out of the simulations, nine suggested that an ice-free day could happen within three to six years.
The researchers noted that a sequence of extreme weather events could lead to the rapid loss of over two million square kilometers of sea ice. For example, an unusually warm fall could weaken the ice, followed by a mild Arctic winter and spring that inhibit ice formation. If such conditions persist for three or more consecutive years, the first ice-free day could occur during late summer.
These types of warm years have already been observed. In March 2022, parts of the Arctic experienced temperatures 50 °F above average, with areas near the North Pole nearing the melting point. Heuzé explained that with ongoing climate change, such extreme weather events are expected to become more frequent and intense.
Sea ice serves a critical role in regulating Arctic temperatures by reflecting sunlight back into space. As ice diminishes, darker ocean waters absorb more solar heat, accelerating warming in the Arctic and across the globe. This feedback loop could also disrupt wind patterns and ocean currents, leading to more severe weather events worldwide.
There is, however, a glimmer of hope. The study emphasizes that significant reductions in greenhouse gas emissions could push back the timeline for an ice-free Arctic and limit the duration of ice-free conditions.
Any reductions in emissions would help preserve sea ice.
Alexandra Jahn, Associate Professor, Department of Atmospheric and Oceanic Sciences Institute of Arctic and Alpine Research, University of Colorado Boulder