A research team has calculated that the Arctic could soon be ice-free during the month of September for the first time since records began, and it could happen as soon as this year.
Sometime between 2035 and 2067, the Arctic could be consistently free of ice in September, according to the study published in the scientific journal Nature Reviews Earth & Environment.
The researchers, led by Alexandra Jahn from the University of Colorado in Boulder in the United States, explain that individual events with high ice loss, such as unusual warmth over several weeks, could lead to an ice-free September this year or soon after.
Records show that September is the month with the least amount of pack ice. In the 1980s, 5.5 million square kilometres of the Arctic Ocean was typically still covered by ice in September.
Since satellite measurements of the pack ice began in 1978, the area has shrunk by an average of 78,000 square kilometres per year, although various feedback systems ensure that the ice area has increased again slightly in some recent years, despite ongoing climate change.
"Overall, atmospheric variability accounts for around 75% of the internal variability of Arctic sea ice," wrote the authors of the study. The amount of ice is therefore strongly dependent on the respective weather conditions and, to a lesser extent, on incoming warm water from the neighbouring oceans.
Jahn and colleagues used selected models from the Climate Model Intercomparison Project 6 (CMIP6) to simulate the change in ice cover under different scenarios of the future development of greenhouse gas emissions.
"If ice-free conditions return to the entire Arctic in the next few decades," the team wrote in the article, "it will probably be the first time in at least 80,000 years, if not over 115,000 years."