As if the melting of the Greenland Ice Sheet wasn’t already a big enough problem, new research has found that the troubled mass of ice is also pumping out water that’s surprisingly rich in the toxic metal mercury. A few uncertainties surround the finding, but it does highlight how the unfolding climate crisis could impact the rest of the natural world and human life in a bunch of previously unforeseen ways. 

The discovery first emerged when scientists sampled waters from three different rivers and two fjords next to the ice sheet, expecting to gather insights into the water’s nutrients. Unexpectedly, they discovered that the waters were teeming with high concentrations of mercury. Off the back of this initial find, the researchers led an international team of scientists to measure mercury concentrations in meltwaters from three glacial catchments on the southwestern side of the Greenland Ice Sheet during the summer melting season. 

Reporting the findings in the journal Nature Geoscience this week, they discovered that this region’s meltwaters contain some of the highest recorded levels of mercury in natural waters. This region was also found to release up to about 42 tons of dissolved mercury each year, around 10 percent of the global water systems’ export into the oceans. 

“There are surprisingly high levels of mercury in the glacier meltwaters we sampled in southwest Greenland,” Jon Hawkings, a postdoctoral researcher at Florida State University and the German Research Centre for Geosciences, said in a statement. “And that’s leading us to look now at a whole host of other questions such as how that mercury could potentially get into the food chain.”

“We didn’t expect there would be anywhere near that amount of mercury in the glacial water there,” adds Rob Spencer, study author and Associate Professor of Earth, Ocean, and Atmospheric Science at Florida State University.

The source of the mercury is unknown, but the researchers say it’s unlikely to be the result of human industrial activity. Instead, suspect that the leaking mercury actually stems from the natural geochemical properties of the Earth, an idea which may raise some worrying prospects.

“All the efforts to manage mercury thus far have come from the idea that the increasing concentrations we have been seeing across the Earth system come primarily from direct anthropogenic activity, like industry, but mercury coming from climatically sensitive environments like glaciers could be a source that is much more difficult to manage,” adds Hawkins.

It also remains to be seen what effect this seeping mercury might have on the wider ecosystem or even human health. Mercury is a toxic element that bioaccumulates in aquatic food webs in the form of the neurotoxin methylmercury. Moreover, the waters around Greenland are a major source of cold-water shrimp, halibut, and cod that are exported worldwide, raising concerns that the thawing ice from Greenland and beyond could potentially be raising the exposure of mercury to humans and ecosystems.

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