Satellite data reveals unprecedented low in Antarctic sea ice
This year, polar sea ice has taken a significant hit. Both the Arctic and Antarctic regions have recorded alarmingly low extents of sea ice, as reported by NASA and the National Snow and Ice Data Center (NSIDC). These organizations utilize satellite technology to monitor sea ice in both polar areas.
On September 19, the Arctic sea ice shrank to its yearly minimum, covering an area of 1.63 million square miles (4.23 million square kilometers). This is the sixth smallest extent since satellite monitoring began. Meanwhile, on September 10, Antarctic sea ice expanded to its maximum for the year, covering 6.5 million square miles (16.96 million square kilometers). This is the smallest maximum extent ever recorded by satellites.
Walt Meier, an expert on sea ice at NSIDC, commented on the significant decrease in Antarctic sea ice, noting that the reduction is evident almost all around the continent. He also highlighted the unusual openness of the Northwest Passage in the Arctic and the presence of more fragmented ice near the North Pole, a phenomenon becoming more common in recent times.
Sea ice undergoes a cycle of melting and freezing each year. Its extent can be influenced by various factors, including wind patterns, ocean temperatures linked to human-caused global warming, and climate phenomena like El Niño, which is currently active.
A major concern with reduced sea ice is the "ice-albedo feedback" mechanism. Sea ice, being reflective, bounces back most of the sun's rays into space. In contrast, the darker open ocean absorbs these rays. As a result, the ocean retains more heat, further hampering the growth of sea ice.
While the extent of sea ice is a crucial metric, its thickness is equally important. Nathan Kurtz, who heads NASA’s Cryospheric Sciences Laboratory, emphasized the role of satellites like NASA’s ICESat-2 in monitoring ice thickness throughout the year. He stressed the importance of combining modern measurements with historical data to gain a comprehensive understanding of the changes occurring.
The decline in Antarctic sea ice this year continues a trend that began after a record high in 2014. Before 2014, the ice around the continent was growing at a rate of about 1% per decade. Scientists are striving to understand the reasons behind the limited growth of Antarctic sea ice, considering factors like El Niño, wind patterns, and rising ocean temperatures. Recent studies suggest that oceanic heat plays a significant role in reducing ice growth during colder seasons and increasing melting during warmer seasons.