The ongoing decline of Arctic sea ice cover is anticipated to persist in the coming years. The prospect of an ice-free Arctic Ocean serves as a stark illustration of the effects of anthropogenic climate change, showcasing a clear shift from a predominantly white Arctic Ocean to one that is largely blue during the summer months. This transition not only reflects changes in the environment but also underscores the broader implications of climate change on global weather patterns and ecosystems.
The first summer on record that melts practically all of the Arctic’s sea ice, an ominous milestone for the planet, could occur as early as 2027. For the first time, an international research team, including CU Boulder climatologist Alexandra Jahn and Céline Heuzé from the University of Gothenburg in Sweden, used computer models to predict when the first ice-free day could occur in the northernmost ocean.
An ice-free Arctic could significantly impact the ecosystem and Earth’s climate by changing 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.”
As climate change accelerates due to rising greenhouse gas emissions, the Arctic sea ice is vanishing at an alarming rate of over 12% per decade—a trend we cannot ignore.
In September, the National Snow and Ice Data Center revealed that this year’s Arctic sea ice minimum—the day with the least amount of ice—ranked among the lowest recorded since 1978. This year’s minimum, at 1.65 million square miles (4.28 million square kilometers), surpassed the all-time low set in September 2012.
However, it starkly contrasts the historical average of 6.85 million square kilometers recorded from 1979 to 1992. Scientists assert that when Arctic sea ice coverage drops below 1 million square kilometers, the region can be considered ice-free.
Earlier studies on Arctic sea ice have primarily aimed to predict when the ocean will remain ice-free for an entire month. Research by Jahn indicated that this milestone may happen as soon as the 2030s—a disturbing forecast. With this tipping point looming on the horizon, Jahn is now questioning when we will witness the first summer day with nearly all Arctic sea ice melted—a scenario that threatens not just the Arctic but the global climate.
“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.
Jahn and Heuzé predicted the first ice-free Arctic day using data from over 300 computer models. They discovered that the majority of simulations indicated that the initial ice-free day could occur between nine and 20 years after 2023, regardless of human efforts to curb greenhouse gas emissions.
The earliest potential ice-free day in the Arctic Ocean might happen as soon as three years from now, with nine simulations pointing to a timeframe of three to six years. The research reveals a critical tipping point: a chain of extreme weather events could rapidly melt two million square kilometers or more of sea ice. This process begins with an unusually warm fall that weakens the ice, followed by a warm Arctic winter and spring that stifles ice formation.
Continuous extreme warming for three years or more could lead to the first ice-free day in late summer, a scenario all too possible given recent climate patterns. For instance, in March 2022, parts of the Arctic experienced temperatures 50°F above average, with regions near the North Pole almost melting.
Heuzé stated that with climate change, these extreme weather occurrences are likely to become more frequent and intense. Sea ice acts as a shield for the Arctic against warming by reflecting incoming solar radiation back into space. With a decline in reflective ice cover, darker ocean surfaces will absorb more solar heat, further elevating temperatures in both the Arctic and globally.
Furthermore, warming in the Arctic could alter wind and ocean current patterns, leading to an increase in extreme weather events globally. On a positive note, the study suggests that implementing drastic cuts in emissions could postpone the timeline for an ice-free Arctic and significantly reduce the duration of time the ocean remains ice-free.
“Any reductions in emissions would help preserve sea ice,” Jahn said.
Journal reference:
- Céline Heuzé & Alexandra Jahn. The first ice-free day in the Arctic Ocean could occur before 2030. Nature Communications, 2024; DOI: 10.1038/s41467-024-54508-3