First ice-free day in the Arctic may arrive in 2027

According to a recent study, the first summer on record when nearly all of the Arctic’s sea ice melts – an alarming milestone for the planet – could occur as soon as 2027.

For the first time, an international team of researchers, including climatologist Alexandra Jahn from the University of Colorado Boulder and Céline Heuzé from the University of Gothenburg in Sweden, has used computer models to forecast when the Arctic Ocean might experience its first ice-free day. 

Implications of an ice-free Arctic 

An ice-free Arctic could have significant impacts on ecosystems and Earth’s climate by altering weather patterns.

“The first ice-free day in the Arctic won’t change things dramatically,” said Jahn, associate professor in the Department of Atmospheric and Oceanic Sciences and fellow at CU Boulder’s Institute of Arctic and Alpine Research. 

“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.”

A rapidly warming Arctic

As global temperatures rise due to increasing greenhouse gas emissions, sea ice in the Arctic has been disappearing at an unprecedented rate of more than 12% each decade.

In September, the National Snow and Ice Data Center reported that this year’s Arctic sea ice minimum – the day with the least amount of frozen seawater – was among the lowest recorded since 1978.

At 1.65 million square miles (4.28 million square kilometers), this year’s minimum was above the all-time low observed in September 2012. 

However, it still represents a significant decline compared to the average coverage of 6.85 million square kilometers between 1979 and 1992.

Scientists consider the Arctic to be ice-free when the ocean has less than one million square kilometers of ice.

Focusing on the first ice-free day

Previous projections of Arctic sea ice have centered on predicting when the ocean will remain ice-free for an entire month. Jahn’s earlier research suggested that the first ice-free month is almost certain and could occur by the 2030s.

As this critical point approaches, Jahn became interested in pinpointing when the first summer day might occur that melts virtually all Arctic sea ice.

“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,” Heuzé said.

Extreme weather and early melt

Jahn and Heuzé estimated the timing of the first ice-free Arctic day using data from over 300 computer simulations. 

They found that most models predict the first ice-free day could happen within nine to 20 years after 2023, regardless of human efforts to reduce greenhouse gas emissions. The earliest ice-free day could occur within three years.

While this is an extreme scenario, it remains a possibility based on the models. In total, nine simulations indicated that an ice-free day could happen in three to six years.

The researchers discovered that a sequence of extreme weather events could melt two million square kilometers or more of sea ice rapidly. An unusually warm fall could weaken the sea ice, followed by a warm Arctic winter and spring that prevent new ice from forming. 

If the Arctic experiences such extreme warming for three or more consecutive years, the first ice-free day could occur in late summer.

Such warm periods have already occurred. For example, in March 2022, areas of the Arctic were 50°F warmer than average, and regions near the North Pole were nearly melting. According to Heuzé, climate change will only increase the frequency and intensity of these weather events.

Hope through emission reductions

Sea ice protects the Arctic by reflecting incoming sunlight back into space. With less reflective ice, darker ocean waters absorb more heat from the Sun, further increasing temperatures in the Arctic and globally. 

Additionally, warming in the Arctic could alter wind and ocean current patterns, leading to more extreme weather events worldwide.

But there is also positive news: a significant reduction in emissions could delay the timeline for an ice-free Arctic and decrease the duration the ocean remains ice-free, according to the study.

“Any reductions in emissions would help preserve sea ice,” Jahn concluded.

The findings were published on December 3 in the journal Nature Communications. Jahn will also present the results on December 9 at the American Geophysical Union annual meeting in Washington D.C.

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