Scientists map increasing extreme weather events on offshore Antarctic islands

Scientists map increasing extreme weather events on offshore Antarctic islands

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Credit: CC0 public domain

Scientists at the British Antarctic Survey have discovered that the number of warm weather events in the South Orkney Islands has increased significantly in frequency over the past 75 years. Using newly available historical data, scientists have identified the weather factors behind warm events in the region, shedding new light on climate change trends affecting sub-Antarctic islands.

Scientists found that warm trends on these islands are closely linked to an increased occurrence of extreme warm events. These extreme weather events are caused by large-scale anomalous atmospheric circulation patterns. The researchers have published two papers. one in International Journal of Climatology And the other in Quarterly Journal of the Royal Meteorological Society.

Atmospheric rivers—long, narrow plumes of water vapor in the atmosphere—capture a large amount of heat and water vapor from the tropical and subtropical oceans and then transport them. These interacted with the mountainous terrain of the South Orkney Islands, resulting in increased melting of ice and snow in the area.

The isolated and mountainous South Orkney Islands are important for Antarctic ecosystems and biodiversity, and extreme warm air temperatures over these islands can alter the ecosystem. The islands are also surrounded by the waters of the Weddell-Scotia Confluence, which are dynamic and productive waters that influence global ocean movement.

“The warming trends we detected have real implications for the sensitive biodiversity of the South Orkney Islands,” said Hua Lu, lead author of both papers. “Signy Island supports one of the richest and most diverse ecosystems in the Southern Ocean. Despite these islands, they are remote and isolated.” “It shows how the Earth's climate systems connect us all, and as historical climate patterns change, we must be prepared to indirectly impact the natural environment and people around the world.”

Credit: British Antarctic Survey

The results are some of the early outputs of the SURFEIT programme, which aims to improve scientific models of interactions between the atmosphere, water, snow and ice, and our ability to predict extreme climate changes in Antarctica.

These new findings are based on meteorological records from two research stations in the South Orkney Islands: the British Antarctic Survey's Cygne Research Station and Argentina's Orcadas Base.

Continuous meteorological records from 1947 to 1995 at Signy Station were made possible thanks to a digitization project supported by the UK's Diversity in Polar Science Initiative. For the first time, newly available historical Signy records have been used to reveal long-term temperature trends and extreme warm events in the region.

more information:
Hua Lu et al., Temperature variation in the South Orkney Islands and offshore Antarctica, International Journal of Climatology (2023). doi: 10.1002/joc.8302

Hua Lu et al., Extreme warm events in the South Orkney Islands, Southern Ocean: the multiplier effect of atmospheric rivers and FON conditions, Quarterly Journal of the Royal Meteorological Society (2023). doi: 10.1002/qj.4578

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