A stunning image captured by Landsat 8 satellite in November 2021 showcases an unusual phenomenon in Antarctica: wispy strands of ice stretching across a narrow channel of water. This rare sight, a result of a combination of high winds and unusual ocean currents, is a potential indicator of the changing climate and its impact on the fragile Antarctic ecosystem.
The ice streaks extended across a 3.7-mile-wide channel between the Ronne Ice Shelf, a massive ice sheet that regularly births colossal icebergs, and a patch of fragmented sea ice. These streaks are composed of nilas, a type of extremely thin ice, less than 4 inches thick, according to the National Snow and Ice Data Center (NSIDC). Typically, nilas forms when loose ice crystals, known as frazil ice, merge into thin sheets on still water. However, in this instance, powerful winds generated unusual whirlpool currents, or vortices, on the ocean surface. These vortices disrupted the formation of sheet ice and forced the nilas ice to congregate at the centers of the currents before being blown across the water, as explained by NASA’s Earth Observatory.
The strong winds also pushed the sea ice away from the Ronne Ice Shelf, providing more space for the nilas to grow and stretch out. In the image, the nilas ice accumulates along the edge of the sea ice, forming a striking pale blue band. This color is unusual for this type of ice, as glaciers and sea ice typically appear blue when they become dense enough to absorb longer wavelengths of light, reflecting only the shorter, blue wavelengths.
Walt Meier, a research scientist at NSIDC, expressed uncertainty regarding the blue color of the sea ice in this instance. He suggested that the ice may have been compressed, making it very compact and allowing it to absorb longer wavelengths than normal.
The occurrence of these icy wisps is likely to become more common in the future due to the effects of climate change. In November 2021, when the image was taken, the Antarctic sea ice extent—the area of ocean around Antarctica covered by sea ice—was significantly below the average for that time of year, according to NASA’s Earth Observatory. Thinner and more fragile sea ice is more susceptible to being moved by the wind, increasing the likelihood of these wispy ice formations appearing in the future. This observation serves as a stark reminder of the vulnerability of Antarctic sea ice to climate change and the potential consequences for the delicate balance of the ecosystem.
