Ancient Antarctic ice melt offers future climate change insight – Oceanographic Magazine
Researchers from British Antarctic Survey and Cambridge University have been able to draw new conclusions about how Antarctica was affected by increased temperatures during the last interglacial, some 100,000 years ago and its impact on sea level rises.Researchers from British Antarctic Survey and Cambridge University have been able to draw new conclusions about how Antarctica was affected by increased temperatures during the last interglacial, some 100,000 years ago and its impact on sea level rises.New and vital evidence confirming that a dramatic Antarctic ice sheet melt took place some 126,000 years ago will now be critical for predicting how future global warming will impact the region’s vast ice sheets and global sea level rises, a team of scientists behind the discovery have said.By looking at data taken from ice core records, researchers from the British Antarctic Survey and the University of Cambridge have been able to draw new conclusions about how Antarctica was affected by increased temperatures during the last interglacial, some 100,000 years ago. Presenting their findings in the scientific journal Nature this week, these scientists have shown how, during a period of warming, large parts of the West Antarctic Ice Sheet were lost, contributing to significant sea level rises several metres above present. While the melt was dramatic, the same data has shown, however, that the nearby Ronne Ice Shelf – which current climate models project could be lost under future warming scenarios – actually survived.It’s widely recognised that greenhouse gas emissions are warming the Earth at an unprecedented speed and scale. While human-induced global warming has no direct comparable period in the planet’s history, episodic warm periods can offer clues to the future.Led by Eric Wolff from Cambridge University, a team of ice core scientists wanted to find out what happened to the West Antarctic Ice Sheet during the last interglacial, when polar regions were around 3°C warmer than present and sea levels were significantly higher. This is a period in Earth’s history scientists believe is comparable to conditions we might see within decades.“Solving the puzzle of how quickly and how much of the Antarctic ice sheet melted during the last interglacial has been a major goal for paleoclimate researchers for decades,” said Louise Sime, a climate scientist at British Antarctic Survey and a contributing author of the new paper.“By drilling and analysing their new West Antarctic SkyTrain ice core, it seems that Eric Wolff and his team have finally got their hands on key evidence that a large loss of ice really did occur 126,000 years ago.”This is a first for scientists who, for years, have been searching for conclusive data showing such major changes to Antarctica in climate records.“This information from the last time Antarctica was warmer than present day is crucial for predicting how and when the West Antarctic ice sheet will change under future warming,” said Sime.Devil rays’ filter-feeding inspires microplastic pollution innovationHistoric win for the ocean: Rosebank oil plans quashedAustralia’s need to ‘take endangered shark off the menu’Sperm whale, orca, and narwhal now protected from UK ivory tradePod vast: Mega cluster of 1,500 dolphins spotted off Monterey BayThe West Antarctic Ice Sheet holds enough fresh water to raise sea levels by around three to four metres. Scientists recognise that this ice sheet is particularly vulnerable to warming because its bowl shape allows seawater to flow under its rim and slowly melt its base. The Ronne Ice Shelf, however, stretches out from the ice sheet into the Atlantic Ocean, forming a floating platform that acts like a buttress that holds back and protects glaciers inland.In 2019, Wolff and the team collected a 651m long ice core from a coastal dome next to the Ronne Ice Shelf known as the Skytrain Ice Rise. Situated just close enough to the West Antarctic Ice Sheet to witness its shrinkage while remaining intact, data collected from the site can now offer scientists a long-term view on the stability of this vast ice sheet, and its contribution to sea level rise.By analysing the composition of water isotopes in the ice core, researchers found that the West Antarctic Ice Sheet was partially lost during the last interglacial, shrinking to perhaps half its modern-day mass. They also measured sea salt contents of the core to gauge the amount of sea spray and, therefore, the site’s proximity to the coast.The data showed that the Ronne Ice Shelf covered a similar extent to today. Although the ice sheet shrunk significantly, this isn’t the ‘catastrophic ice sheet collapse’ that some reconstructions have previously suggested could have happened at this time. Despite this, it’s still acknowledged that sea level rise was significantly higher at this time.The researchers now say that these findings will help improve forecasts of what could happen to ice sheets as our climate warms. One of the largest uncertainties in long-term sea level projections, including those made by the IPCC, is the fate and stability of the West Antarctic Ice Sheet.Nick Golledge, co-author from the Victoria University of Wellington, said: “Data like those from Skytrain Ice Rise are invaluable for modellers trying to understand how the West Antarctic Ice Sheet might behave under future warming. “They offer a window into what actually happened in the past, allowing the sensitivity of our models to be accurately calibrated. Without this kind of information, our projections for the future will never be as accurate as we’d like them to be.” Click here for more from the Oceanographic Newsroom.”*” indicates required fieldsThe worlds biggest ocean news.
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