The long-held assumption that ice-trapped iron in the Antarctic’s glaciers would slow the impact of global warming as the ice melts, has been overturned – challenging how climate change predictions are forecasted and modeled. 

The theory that iron in glaciers would feed blooms of microscopic algae, and sequester carbon dioxide into the atmosphere as they grow had been widely accepted.

However, new research published from Rutgers University-New Brunswick’s marine scientists have challenged this longstanding assumption.

A team of researchers collected data and meltwater during an expedition to the Dotson Ice Shelf, in the Amundsen Sea in West Antarctica. Until now, scientific understanding of iron sources in these waters had come from computer models and simulation. 

The Amundsen Sea accounts for most of the sea level rise driven by Antarctic melting.

On expedition, they collected glacial meltwater at its source. Postdoctoral scholar and lead author of the study Venkatesh Chinni, then analysed the water’s iron content to understand its chemical “fingerprint” and origins. 

In sharp contrast to existing scientific understanding, they found that meltwater itself actually carries very little iron.

“Roughly 90% of the dissolved iron coming out of the ice shelf cavity comes from deep waters and sediments outside the cavity, not from meltwater,” Chinni said.

They also discovered a chemical mechanism beneath the glacier which causes iron to be released from the bedrock underneath the glacier – this, they believe, may be contributing more iron than melting ice shelves do.

Robert Sherrell, a professor in the Department of Marine and Coastal Sciences at Rutgers, and the study’s principal instigator: “Our claim in this paper is that the meltwater itself carries very little iron, and that most of the iron that it does carry comes from the grinding up and dissolving of bedrock into the liquid layer between the bedrock and the ice sheet, not from the ice that is driving sea level rise.”

Sherrell added that many scientists may find this conclusion surprising.

Researchers have said the findings do not just raise questions about the sources of iron within melt water in Antarctica, they also significantly alter how climate change predictions are forecasted and modelled.

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