The Arctic Ocean could have its first ice-free day as soon as 2027, marking an “ominous milestone for the planet”, according to an alarming new report pulled together by a team of international researchers warning over the crucial need to reduce greenhouse gas emissions drastically.

As the climate warms from increasing greenhouse gas emissions, sea ice in the Arctic has been melting at an “unprecedented speed” of more than 12% each decade. At such a rate, it is inevitable that the Arctic Ocean will be ice-free within the next 20 years, scientists warn.

The study – led by researchers from the University of Colorado Boulder – warns that regardless of how much we alter our greenhouse gas emissions now, this “ominous milestone for the planet” will almost certainly be reached within nine to 20 years after 2023. In fact, the study’s lead authors, Alexandra Jahn (a climatologist at the University of Colorado Boulder) and Céline Heuzé from the University of Gothenburg in Sweden suggest that the earliest ice-free day in the Arctic Ocean could occur within three years.

To draw the conclusion, scientists have used computer models to predict when the first ice-free day would occur in the northern-most ocean, finding that an ice-free Arctic could significantly impact the ecosystem and Earth’s climate by changing weather patterns.

While Jahn – an associate professor in the Department of Oceanic Sciences and fellow at the University of Colorado Boulder’s Institute of Arctic and Alpine Research – has admitted that the the first ice-free in the Arctic shouldn’t “change things too dramatically” it will present an ominous foreshadowing for an environment naturally covered by sea ice and snow perennially.

“It will show that we have 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.”

The findings of the study first appeared in the journal Nature Communication this week and will be presented by Jahn at the American Geophysical Union annual meeting in Washington DC on December 9.

In September this year, the National Snow and Ice Data Centre reported that the Arctic sea ice minimum – the day with the least amount of frozen seawater in the Arctic – was one of the lowest on record since 1978. At 1.65 million square miles, this year’s minimum was above the all-time low observed in September 2012. However, it still represents a stark decline compared to the average coverage of 6.86 million square kilometres between 1979 and 1992.

The Arctic is officially considered by scientists to be ‘ice-free’ when its ocean has less than one million square kilometres of ice coverage.

Previous projections of Arctic sea ice change have focused on predicting when the ocean will become ice-free for a full month. Jahn’s prior research suggested that the first ice-free month would occur almost inevitably and might happen by the 2030s.

But as the tipping point approaches, Jahn wanted to know when the first summer day that melts virtually all 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,” said Heuzé.

Jahn and Heuzé made their estimates using output from over 300 computer simulations and found that most models placed the first ice-free day within nine and 20 years of 2023. The earliest ice-free day in the Arctic Ocean could occur within three years.

In total, nine simulations suggested that an ice-free day could occur in three to six years.

The researchers found that a series of extreme weather events could melt two million square kilometres of sea ice or more in a short period of time. Such conditions conducive to this event would involve an unusually warm autumn, which would first weaken the sea ice, followed by a warm Arctic winter and spring, preventing sea ice from forming. When the Arctic experiences such extreme warming for three or more years in a row, the first ice-free day could happen in late summer.

Critical to note is that we have already experienced years like these.

In March 2022, areas of the Arctic were 50°F warmer than average, and areas around the North Pole were nearly melting. With climate change, the frequency and intensity of these weather events will only increase, says Heuzé. And, like a domino effect with global consequences; with a warming Arctic, wind and ocean current patterns could be altered significantly, leading to more extreme weather events around the world.

There is, however, a small window of hope, the pair have insisted. The good news is that a drastic cut in global greenhouse gas emissions now could delay the timeline for an ice-free Arctic and thus reduce the time the Arctic Ocean stays free of ice cover.

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

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