New research led by polar scientists at Northumbria University has uncovered a surprising source of long-term climate hope hidden within East Antarctica’s changing landscape. As the continent’s ice sheets thin under a warming climate, newly exposed mountain peaks may dramatically increase the supply of essential nutrients to the surrounding Southern Ocean – potentially strengthening its natural ability to absorb carbon dioxide from the atmosphere over long periods of time.

The study, published in Nature Communications, brings together expertise in oceanography, ice-sheet modelling and geochemistry.

By analysing sediment samples from the Sør Rondane Mountains, the team discovered that rocks weathered above the ice surface contain iron concentrations up to ten times higher than previously recorded from Antarctica. This bioavailable iron – transported to the ocean by glaciers and icebergs – fuels phytoplankton growth, a key biological process that absorbs CO₂ through photosynthesis.

The scientists found that sediments from nunataks – mountain peaks protruding through the ice – contained more than three times the amount of extractable iron compared to material already being carried toward the coast by glaciers. Several visibly rust-stained samples showed especially high iron levels, pointing to weathering on exposed surfaces as a powerful driver of nutrient enrichment.

“Our results show that exposed bedrock in Antarctica acts like an iron factory,” said Dr Kate Winter, Associate Professor in the School of Geography and Natural Sciences at Northumbria University and lead author of the paper. “Even though air temperatures rarely rise above freezing, sunlight can heat dark rock surfaces to over 20°C in summer, creating the conditions needed for weathering and the formation of bioavailable iron compounds.”

Winter, supported by a Baillet Latour Antarctica Fellowship has conducted several field campaigns at Princess Elisabeth Antarctica, gathering data that help link terrestrial processes to ocean ecosystems.

Satellite observations show that coastal waters near glacier outlets in the study region regularly experience phytoplankton blooms, confirming the biological significance of this natural iron supply. These blooms reinforce the Southern Ocean’s role as one of the planet’s major carbon sinks.

“The exciting thing is that we can take some hope from these findings because we know that carbon dioxide is a really important factor in climate change,” Winter added. “From our research we now know that sediments from the Antarctic continent could help to draw down atmospheric carbon dioxide into the ocean. Although our study area covers just one glacier system, the big question is what happens when we scale up these many small contributions across the whole of Antarctica.”

The research team has cautioned, however, that this process operates on very long timescales. In fact, ice-flow models show that iron-rich sediments generated in the mountains today may take between 10,000 and 100,000 years to reach the coast.

“While the sediments we examine in the mountains today will take a long time to reach the ocean, we know from seafloor surveys that iron-rich sediments have been delivered to the coast for millennia,” said Dr Sian Henley of the University of Edinburgh. “The processes we record today give us a glimpse into the changes we might expect in the future as glaciers thin and more mountain surfaces are exposed.”

As temperatures continue to rise, the study suggests several factors will amplify iron delivery to the Southern Ocean, including the emergence of more mountain peaks from thinning ice sheets, the additional supply of sediment to glaciers from increased rock slope failures, the generation of more bioavailable iron by weathering, and the dispersal of iron-rich material across wide ocean regions by icebergs.

The research offers new insight into how Antarctica’s extreme environment connects with marine ecosystems and global carbon cycles and hints at how this system may shift as climate change continues to reshape the continent.

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