According to researchers from NASA and the National Snow and Ice Data Center (NSIDC), 2023 marked the sixth-lowest year for Arctic sea ice since satellite measurements began, likely hitting its annual minimum extent on September 19.
Meanwhile, Antarctic sea ice reached a record-breaking minimum, hitting its lowest maximum extent on September 10, a time when the ice cover is usually expanding rapidly during the coldest and darkest months.
Understanding the seasonal and yearly changes in sea ice is essential since this ice plays a pivotal role in shaping Earth’s polar ecosystems and influencing the global climate.
Scientists from NASA and NSIDC employ satellites to gauge sea ice during its melting and freezing cycles, focusing on sea ice extent, which represents the total ocean area with at least 15 percent ice cover.
From March to September 2023, Arctic ice cover diminished from a peak area of 14.62 million square kilometers to 4.23 million square kilometers.
This is approximately 1.99 million square kilometers below the average minimum from 1981–2010, representing a loss enough to cover the entire continental United States.
At the same time, Antarctic sea ice reached a record low winter maximum extent of 16.96 million square kilometers, about 1.03 million square kilometers below the former record-low set in 1986.
“It’s a record-smashing sea ice low in the Antarctic,” said Walt Meier, a sea ice scientist at NSIDC. “Sea ice growth appears low around nearly the whole continent as opposed to any one region.”
This year, the Northwest Passage in the Arctic also saw notably low ice levels, indicating more open areas and a higher presence of loose, lower concentration ice.
The sea ice modifications are a result of warming temperatures over the decades. “It is more open there than it used to be. There also seems to be a lot more loose, lower concentration ice – even toward the North Pole – and areas that used to be pretty compact, solid sheets of ice through the summer. That’s been happening more frequently in recent years,” Meier reported.
According to Nathan Kurtz, the director of NASA’s Cryospheric Sciences Laboratory, the growing thinness of the ice is due to the Arctic warming about four times faster than the rest of the planet.
“Thickness at the end of the growth season largely determines the survivability of sea ice. New research is using satellites like NASA’s ICESat-2 (Ice, Cloud, and land Elevation Satellite-2) to monitor how thick the ice is year-round,” he explained.
As Kurtz stresses, connecting current measurements to historical records is essential for understanding the driving forces behind these changes.
“At NASA we’re interested in taking cutting-edge measurements, but we’re also trying to connect them to the historical record to better understand what’s driving some of these changes that we’re seeing,” he said.
The scientists are delving deeper to decipher the causes behind the scant growth of Antarctic sea ice. Various factors such as El Nino, alterations in wind patterns, and rising ocean temperatures are currently being investigated.
Recent research indicates that ocean heat is likely a significant factor in delaying ice growth and enhancing melting during the warm season.
This year’s record-low extent is part of a continuing downward trend in Antarctic sea ice that began after 2014, reversing a slight increase of about one percent per decade before 2014.
The diminishing sea ice at both poles enhances warming through the “ice-albedo feedback” cycle, which leads to more solar energy absorption by the ocean, warming the ocean waters and further impeding sea ice growth.
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