Large Stores of Iron from Melting Ice Sheets May Buffer Global Warming Impacts

While ice sheets may be melting faster than ever before, it might not all be bad news. Scientists have found that summer meltwaters from ice sheets are rich in iron, which will have a major impact on phytoplankton growth and will, in turn, impact climate change models.

Bioavailable iron can boost phytoplankton growth since these tiny organisms need iron in order to thrive and reproduce. Phytoplankton, in turn, captures carbon and can therefore buffer the effects of global warming. These organisms also feed into the bottom of the oceanic food chain and provide a food source for marine animals.

In order to see exactly how much iron was being released by ice sheets, the researchers collected meltwater discharged from the Leverett Glacier in Greenland over the summer of 2012. The water was tested for iron content. In the end, the scientists found that the melting ice sheet contained significant quantities of bioavailable iron.

"The Greenland and Antarctic Ice Sheets cover around 10 percent of global land surface," said Jon Hawkings, one of the researchers, in a news release. "Iron exported in icebergs from these ice sheets have been recognized as a source of iron to the oceans for some time. Our finding that there is also significant iron discharged in runoff from large ice sheet chatchments is new. This means that relatively high iron concentrations are released from the ice sheet all summer providing a continuous source of iron to the coastal ocean."

In fact, the researchers estimate that the flux of bioavailable iron associated with glacial runoff is between 400,000 and 2,500,000 tons per year in Greenland and between 60,000 and 100,000 tons per year in Antarctica.

Currently, scientists aren't sure how much additional iron will be released into the oceans via increased ice sheet melting. However, it could have a significant impact on coastal ecosystems and the oceans. It could help spark phytoplankton blooms which could, in turn, could impact the rate of global warming.

The findings are published in the journal Nature Communications.