A study published in Nature Climate Change has revealed what reportedly caused the drastic change in Antarctic sea ice, which expanded for decades each winter before rapidly declining starting in 2015. According to the study, the change is likely one of the largest witnessed in Earth's climate system. Researchers focused on a cold water layer under the sea ice that prevents warmer deep water from rising and melting the ice from below.
Until 2015, this protection allowed the sea ice to grow, but beneath the surface, it reportedly weakened as deep water warmed due to climate change. In 2015, strong winds reportedly enabled the warm water below to break through the cold layer, making it easier for warm water to reach the surface and contribute to the sea ice decline. The study, led by Theo Spira, compiled data from various sources, including elephant seals equipped with sensors that measure water temperature, salinity, and depth.
These seals reportedly play a huge role in providing data from the Southern Ocean, covering hard-to-reach areas. The discovery is important for understanding the Antarctic sea ice's role in the climate, as it reflects solar radiation and blocks heat exchange between the ocean and atmosphere. The Southern Ocean is reportedly extremely important for the global climate due to its role in climate change, affecting heat uptake and carbon dioxide storage.
The study shows processes that have been poorly represented in climate models, and Spira hopes the research will contribute to better models in the future. It remains unclear whether the sea ice extent around Antarctica will stabilize, continue to decrease, or possibly recover.