Disappearing Antarctic ice: The biggest climate alarm

Sea ice in Antarctica it usually shrinks to its smallest size towards the end of February, during the continental summer, and then gradually recovers over the winter. However, this year has deviated from the norm. Sea ice has not recovered to expected levels and is currently at the lowest levels for this time of year since records began 45 years ago. The ice is about 1.6 million square kilometers (0.6 million square miles) below the previous winter record set in 2022, according to the National Snow and Ice Data Center (NSIDC).

There was sea ice in Antarctica in mid-July 2.6 million square kilometers (1 million square miles) below the average from 1981 to 2010. That's an area nearly as large as Argentina or the combined areas of Texas, California, New Mexico, Arizona, Nevada, Utah, and Colorado. This drastic decrease in sea ice has been described by some scientists as a once-in-a-million-year event, signaling a significant shift in our planet's climate system.

Antarctica is a distant, complex continent. Unlike the Arctic, where sea ice is on a consistently downward trajectory due to the accelerating climate crisis, Antarctic sea ice has fluctuated from record highs to record lows in recent decades. This variability has made it difficult for scientists to understand how it responds to global warming. However, they have been since 2016 saw a sharp drop. Although natural climate variability affects sea ice, many scientists believe that climate change may be an important factor in the ice's disappearance.

Several factors are contributing to the loss of sea ice, including the strength of westerly winds around Antarctica, which have been linked to an increase in planet-warming pollution. "Warmer ocean temperatures north of the Antarctic Ocean boundary mixing into water that is normally somewhat isolated from the rest of the world's oceans is also part of this idea of how to explain it," Scambos said.

Sea ice loss plays a critical role in the health of our planet. Although it doesn't directly affect sea level rise since it already floats in the ocean, its disappearance leaves coastal ice sheets and glaciers exposed to waves and warm ocean waters, making them more vulnerable to melting and breaking off. This could have significant impacts on wildlife, including krill, whales, penguins and seals, which rely on sea ice for feeding and resting.

In addition, sea ice in Antarctica helps regulate the temperature of the planet. Sea ice reflects incoming solar energy back into space. As it melts, it exposes the darker ocean waters below, which absorb the sun's energy, further accelerating global warming.

Parts of Antarctica have been seeing alarming changes for some time. The Antarctic Peninsula, a chain of icebergs emerging from the western side of the continent, is one of the fastest-warming places in the southern hemisphere. Last year, scientists warned that the vast Thwaites Glacier in West Antarctica - also known as the "doomsday glacier" - was on the verge of collapse. If Thwaites were to fail completely, global sea level rise could increase by about 10 feet—that's about 3 meters. Which would be disastrous for coastal communities around the world.

Record low sea ice level this winter is a stark warning signal. As one scientist put it, "something important in a large part of the planet is suddenly behaving differently from what we've seen in the last 45 years." This dramatic change in Antarctic sea ice is a clarion call to action for humanity to tackle the growing climate crisis.