Study reveals how delayed Antarctic melt season reduces albedo feedback

The continent of Antarctica, covered in ice, is not immune to the effects of climate change. In fact, the rise in temperatures in high latitudes is more significant than the global average, resulting in what is known as the polar amplification effect. This phenomenon has caught the attention of a research team led by Prof. Guo Huadong from the International Center of Big Data for Sustainable Development Goals (CBAS) and the Aerospace Information Research Institute (AIR) of the Chinese Academy of Sciences (CAS), along with their collaborators. Their investigation into the ocean-ice-atmosphere interaction mechanism of the region has been published in the National Science Review.

To analyze the impact of climate change on the Antarctic ice sheet, the team developed a novel method. They used machine learning and passive microwave remote sensing data, as well as temperature observation data from automatic weather stations, to detect surface snowmelt on the ice sheet. The research revealed that over the past 40 years, from 1978 to 2020, there has been a delay in the melting season of the Antarctic ice sheet.

The delay is not limited to the onset of the melting season but also extends to its end. Approximately 67% of the snowmelt regions in Antarctica experience delays in the onset of melt, while 65% experience delays in termination. Overall, the accumulated delays during the 40-year period account for 10%–15% of the entire summer melt duration.

The research team identified the mechanisms behind this delay. They found that in late spring and early summer, as the westerly jet moves towards the poles, surface temperatures near the poles drop, resulting in a delay in the start of the Antarctic ice sheet melting. Similarly, at the end of the Antarctic summer, the shrinking sea ice leads to increased heat transfer from the ocean to the atmosphere, causing a delay in the end of the ice sheet surface melting.

Furthermore, the researchers assessed the impact of the delayed melting season on surface net solar radiation. They discovered that the delay in snowmelt regions affects the annual surface net solar radiation, decreasing it by -5±3×10¹⁸ J/year (or -0.26± 0.14 W/m²). This impact is more significant than the changes in surface net solar radiation (-0.19±0.31 W/m² per year) caused by the increase in sea ice.

The study concludes that incorporating the process of surface melting in ice sheet and climate models will lead to improved predictions of regional climate change, ice sheet mass balance, and sea level rise.

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