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The Arctic is projected to go ice-free for the first time by August or September of 2030 under all emission scenarios, according to a new study.
Further, the Arctic Ocean could see frequent occurrences of ice-free conditions by mid-century (by 2035–2067), the paper published in journal Nature Reviews Earth & Environment stated.
“Our study also focuses on the frequency of ice-free conditions, rather than just when the first-time ice-free conditions are reached,” Alexandra Jahn, from the University of Colorado Boulder, told Down To Earth.
This, she added, is important as Arctic sea ice will not cease to exist after going ice-free for the first time. “So it is important to also know how frequently ice-free conditions will reoccur in the future,” she noted.
Arctic sea ice cover – which includes the sea ice area, extent, and thickness — has declined since the beginning of satellite observations in 1978. They could see ice-free conditions occur in the next few decades, probably the first for at least 80,000 years.
“The transition to an ice-free Arctic signifies a regime shift from a perennial sea ice cover to a seasonal sea ice cover, or from a white summer Arctic to a blue Arctic,” the researchers wrote in their review.
Jahn and her colleagues outlined predictions of the ice-free Arctic, including for September and other months. To quantify ice-free projections, the team analysed monthly sea ice using climate models.
After reviewing papers for the definition of ice-free conditions, they found that they have varied over time.
Previously, it was referred to as the nearly complete disappearance of all sea ice. But now, scientists have agreed to designate the Arctic ice-free when the ocean has less than 1 million square kilometres of ice.
In recent years, the Arctic Ocean had around 3.3 million square kilometres of sea ice at its minimum in September. Arctic sea ice reaches its minimum extent in September every year.
The paper highlighted that under all future emission scenarios, the first ice-free day in the Arctic could occur over 10 years earlier than previous projections.
The frequency at which ice-free conditions occur could vary depending on future warming levels. For instance, if ice-free conditions occur for warming of 1.5 degrees Celsius, they are unlikely to reoccur for several decades.
But if warming exceeds 2°C or 3°C, September ice-free conditions would likely re-occur every two or three years or almost every year, respectively.
And if temperatures stay within the 1.5 °C mark or only exceed this limit for a short time, there is a less than 10 per cent chance that the Arctic will not become ice-free.
The paper also said the Arctic is resilient and can bounce back to normalcy if the atmosphere cools down.
Model projections show a decline in the probability of the Arctic facing ice-free conditions when temperatures go down by 2050 by removing carbon dioxide from the atmosphere.
“This recovery follows the same relationship as the melt, so we get the same amount of sea ice back for a given cooling as we lose for a given warming,” Jahn explained.
The team next plans to look at predictions of daily ice-free conditions, which has not been done so far.