Antarctica sea ice opening explained by atmospheric rivers

Researchers have identified a likely cause for a massive opening in the Antarctic sea ice that occurred in August 2024. An area of open water, known as a polynya, formed in Breid Bay, East Antarctica, covering approximately 89,000 square kilometers—an area comparable to the size of Portugal.

An Indian research team led by Jeebanjyoti Swain from Bharathidasan University analyzed satellite data from 1979 to 2024 alongside maritime and meteorological measurements. The study, published in Geophysical Research Letters, attributes the phenomenon to a rare interaction between the atmosphere and the ocean.

During July and August 2024, the region was struck by six atmospheric rivers—narrow corridors of air that transport significant heat and moisture toward the poles. These rivers triggered heatwaves that raised air temperatures by approximately 19 degrees Celsius above the seasonal average. This warmth, combined with thick cloud cover and snowfall that acted as an insulating blanket, prevented new ice from forming. Additionally, strong winds drew warmer water from deeper ocean layers to the surface, creating a marine heatwave.