Antarctica's sea ice failed to recover to anything close to a typical winter high in 2026, deepening concern among scientists tracking conditions at both poles.
Here's what to know
Carbon Brief reported that provisional data from the U.S. National Snow and Ice Data Center shows the continent's sea ice reached its annual winter peak on Sept. 14 at 6.79 million square miles (17.59 million square kilometers), making it the third-smallest winter maximum in the 48-year satellite record.
NSIDC cautioned that the number is not yet final because Antarctic sea ice often swings markedly around the time of its seasonal high.
Describing the 2026 maximum as "well below average for the season," Dr. Lettie Roach, a polar climate scientist at Germany's Alfred Wegener Institute, said it is troubling that "after several decades of stable or increasing winter Antarctic sea ice conditions, it is concerning to see these low values persisting".
The monthly winter readings remained unusually depressed, according to Dr. Clare Eayrs, a postdoctoral researcher at the Korea Polar Research Institute: July posted the fifth-lowest extent on record and August the fourth-lowest. She said Antarctic sea ice stayed unusually low through the heart of winter, adding that "all five of the lowest July extents have occurred since 2022 and all four of the lowest August extents since 2023".
On Sept. 12, Arctic sea ice fell to its 2026 summer low of 1.78 million square miles (4.60 million square kilometers), tying with 2025, 2010, and 2008 for the 10th-smallest extent in the satellite era.
TCD Picks » Quince Spotlight
💡These best-sellers from Quince deliver affordable, sustainable luxury for all
More background
The Antarctic trend stands out in part because sea ice around the southern continent has historically been more variable — and harder to interpret — than sea ice in the Arctic. That makes repeated weak winter seasons especially notable, even as researchers continue trying to determine how much of the decline is tied to natural variability versus longer-term warming.
Eayrs said the regional ice pattern also shifted dramatically over the growth season. In April, the Bellingshausen Sea was "almost entirely ice-free," while the nearby Amundsen Sea held more ice than usual. By late August, she said that pattern had largely reversed, with deficits emerging in the Amundsen Sea and across large parts of East Antarctica.
Sea ice helps reflect sunlight back into space, buffers coastlines and ice shelves from ocean waves, and supports marine ecosystems that depend on cold, stable conditions. Changes at the poles can also influence weather patterns, ocean circulation, and the pace of climate disruption.
The NSIDC noted that every one of the 20 lowest Arctic summer minimums in the satellite record has occurred since 2007.
What's being done?
Scientists are continuing to monitor sea ice closely using satellites, seasonal observations, and climate models to determine whether Antarctica is entering a more sustained low-ice period.
Carbon Brief reported that an ice-thickness reanalysis called PIOMAS — short for the Pan-Arctic Ice Ocean Modeling and Assimilation System — stopped updating after the National Oceanic and Atmospheric Administration ended a global air-pressure dataset used to produce it. The PIOMAS website said it will take "considerable effort and time" to identify replacement data.
Roach said: "Compared with the Arctic, it's less clear how recent changes in Antarctic sea ice are attributable to human-caused warming vs natural variability. We need more years of observations to better understand whether this is truly a structural shift."
Where can I learn more?
These stories dig deeper into the polar changes scientists are tracking in Antarctica and the Arctic.
• In the Southern Ocean, waters were substantially modified as Antarctic sea-ice losses mounted.
• Across both poles, the cooling power of sea ice weakened as reflective cover shrank.
• Smoke from the Amazon sped up Antarctic ice melt by darkening snow over the continent.
Get TCD's free newsletters for easy tips, smart advice, and a chance to earn $5,000 toward home upgrades. To see more stories like this one, change your Google preferences here.
