Study: Carbon From Melting Glaciers May Affect Food Chain

Feb 9, 2015

This East Greenland ice sheet is melting, releasing copious amounts of organic carbon as it thaws.
Credit Christine Zenino/flickr

Warmer temperatures are causing glaciers to melt in places like Antarctica and Greenland. What’s in those glaciers may have a significant effect on ecosystems downstream. Those massive chunks of ice harbor a lot of organic carbon – like soot and byproducts from fossil fuel combustion.

All water, from tap water to the oceans, is full of organic carbon in varying forms and concentrations.

Dr. Robert Spencer, assistant professor of oceanography at Florida State University, is studying the potential impact of so much organic carbon being released when glaciers melt. He sat down with us to explain his research and talk about the work ahead.

Aside from sea level rise, why should we care so much about glaciers and ice sheets?

Where we work in the Gulf of Alaska, there are systems that are changing incredibly rapidly. If you think about it from a global perspective, by 2040 or 2050, we’re looking at an approximate 50 percent decline of mountain glaciers on the Tibetan Plateau. And we want to know fundamentally as scientists – what does that mean for downstream receiving environments?

That brings us to organic carbon, which you’ve referred to as the relics of life.

These can be things from fossil fuel byproducts. So, when we combust fossil fuels, that goes into the atmosphere and when that falls in precipitation as snow, it gets into these glacial environments. We could (also) be looking at contemporary carbon dioxide. What we’re really interested in is what then happens to that carbon that’s coming from these either modern or very ancient life forms and where it’s going into the environment upon thaw.

You talk about how in the next 35 years, there will be 50 percent more organic carbon entering the oceans from glaciers. Why do you think that’s the case?

This study that we conducted is basically the first time myself and colleagues have put forward a global estimate of how much organic carbon is both stored within glaciers and then how much will be released from those environments and how that’s changing.

In my opinion, one of the most interesting findings from this study is that by 2050, we’re going to see this increase in organic carbon export, and that’s predominantly driven by mountain glaciers and the decline of mountain glaciers, which we hear a lot about in the media. So this study really shows what that means not just for the water question, but what it also means for things like organic carbon that go along with water as the ice thaws into rivers and streams.

We can now begin to look at what that means for microbes in those streams and things that feed on microbes. That might be zooplankton, but then birds and fish feed on those. So, we’re talking about understanding the base of the food web and how that’s changing, with clear ramifications for what that means for things like fisheries, which obviously we care about from an economic standpoint.