Melting glaciers dump massive amounts of carbon into the world's oceans, a new study finds.
The organic carbon could be a temporary boon for tiny creatures at the bottom of the aquatic food chain that gobble the compound as food, but if this manna disappears because the glaciers have vanished, the overfed ocean ecosystems may collapse, the study authors warned.
"It could change the whole food web. We do not know how different ecological systems will react to a new influx of carbon," study co-author Robert Spencer, an assistant professor of oceanography at Florida State University, said in a statement.
Organic carbon is derived from plants or animals. The compound typically ends up in glaciers from microbes living in the ice, or from soot and other oil and gas byproducts. [Image Gallery: Greenland's Melting Glaciers]
Eran Hood, lead study author, and his colleagues estimated how much organic carbon is trapped in the world's glaciers and ice sheets, and how much will be released into the sea if melting continues its rapid pace. The supply of organic carbon in the world's waterways will increase by 50 percent in the next 35 years, according to the study, which was published Monday (Jan. 19) in the journal Nature Geoscience. That's about half the amount of organic carbon spilled into the sea each year by the Mississippi River, the researchers said.
"This research makes it clear that glaciers represent a substantial reservoir of organic carbon," said Hood, a scientist at 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," he said. These high-latitude ecosystems are now receiving fairly limited inputs of organic carbon from land, Hood said in the statement.
Glaciers are shrinking nearly everywhere on Earth because of global warming, research studies have found. In West Antarctica, melt rates have tripled in the last decade, according to a study published in December 2014 in the journal Geophysical Research Letters. Ice loss in Greenland is five times faster now than in the early 1990s, scientists reported in November 2012 in the journal Science.
The researchers said they are planning follow-up studies to determine whether the predicted glacial carbon will be a menace or a mere nuisance to ocean ecosystems.
"We know we're losing glaciers, but what does that mean for marine life, fisheries, things downstream that we care about? There's a whole host of issues besides the water issue," Spencer said.