Melting glaciers are adding more than water to our oceans

Most concerns about melting glaciers focus on how they contribute to rising sea levels, but scientists are now looking at another problem – what happens to all the organic carbon that was trapped under the ice and is released as it melts?

“This is the first attempt to figure out how much organic carbon is in glaciers and how much will be released when they melt,” says Florida State University assistant professor Robert Spencer of a new study he has been part of.

“It could change the whole food web. We do not know how different ecological systems will react to a new influx of carbon.”

Glaciers and ice sheets contain about 70% of the Earth’s freshwater but they also store organic carbon derived from both primary production on the glaciers and deposition of materials such as soot or other fossil fuel combustion byproducts.

Spencer, along with colleagues from Alaska and Switzerland, studied measurements from ice sheets in mountain glaciers globally, the Greenland ice sheet and the Antarctic ice sheet to measure the total amount of organic carbon stored in the global ice reservoir.

They found that, as glaciers melt, the amount of organic carbon exported will increase 50% over the next 35 years – the equivalent to half the organic carbon in the Mississippi River being added each year to the ocean.

“This research makes it clear that glaciers represent a substantial reservoir of organic carbon,” said Eran Hood, the lead author on the paper published in Nature Geoscience, and a scientist with the University of Alaska Southeast.

“As a result, the loss of glacier mass worldwide, along with the corresponding release of carbon, will affect high-latitude marine ecosystems, particularly those surrounding the major ice sheets that now receive fairly limited land-to-ocean fluxes of organic carbon.”

Spencer says that the study is a wake-up call, emphasising that there is a host of issues besides water levels.

“The thing people have to think about is what this means for the Earth,” Spencer said. “We know we’re losing glaciers, but what does that mean for marine life, fisheries, things downstream that we care about?”

Please login to favourite this article.