Warming Peatlands Emit Carbon Faster than Previously Known
Stephen Sebestyen: If you're driving on the Chippewa National Forest in north-central Minnesota, all of a sudden you'll just come to a place where you see a divergence in the road—you start to see some buildings—you'll look the opposite direction, and off in the distance, you start to see a black spruce peatland. And oddly enough, beyond that, you just start to see these structures rising out of the peatland. And, what they are are aluminum frames with greenhouse glass, essentially. Some people have compared it to the science fiction scene of an alien landing spot on planet Earth. In reality, what this turns out to be is, the world's largest climate change experiment. And, everything in this experiment is pretty much an engineering feat. Building structures on unstable saturated ground, it is truly a marvel of engineering—much of which was figured out by the amazing engineering staff down at Oak Ridge National Lab.
Randy Kolka: The really unique and novel aspect about SPRUCE [Spruce and Peatland Responses Under Changing Environments] is the below ground warming. And so, some engineers at Oak Ridge figured that if you put a pipe in the ground and you add electricity to it, you can heat the ground as far and as deep as you really want. And no one's ever figured that out before.
Stephen Sebestyen: And that's what's not been simulated in the past, is the combination of heating that is going to affect both the above ground ecosystem and the below ground ecosystems. That's the unique aspect of it.
Randy Kolka: Some of the more interesting results coming out is that we're actually flipping these ecosystems from sinks to sources, and not just small sources, huge sources, sources that we are able to measure the elevation change in the actual peatland itself.
Randy Kolka: My name is Randy Kolka. I'm a research soil scientist in Grand Rapids, Minnesota.
Stephen Sebestyen: Hi, I'm Steve Sebestyen. I'm a research hydrologist based in Grand Rapids, Minnesota.
Randy Kolka: The planning for SPRUCE started in 2009, we were really started up and running in the summer of 2014, but that and the paper is through, I think, 2019, but we plan to run the experiment another five or six years. So, there'll be updates on what we found in the paper.
Peatlands occupy just 3 percent of the planet but store about 30 percent of the soil carbon in terrestrial landscapes. A team of scientists is exploring whether climate change could transform peatlands from a carbon sink to a carbon source and, if so, how quickly.
New research findings show that experimental warming causes peatlands to shift from net carbon accumulation to carbon sources faster than anticipated, suggesting that increased rates of global warming will have a significant impact on naturally stored carbon with important feedbacks to the atmosphere. Increased rates of carbon dioxide and methane losses from peatlands could enhance the rate of global warming as those are the two main greenhouse gases causing global warming. In one of the most significant studies emerging from the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment to date, a team that includes Northern Research Station scientists calculated carbon loss rates under four warming scenarios. They found that loss rates are 4.5 to 18 times faster than the rate of historical accumulation at the Marcell Experimental Forest in northern Minnesota. The study provides the first documentation of a clear pattern of carbon loss in a warmer future. An initiative of the Department of Energy, SPRUCE includes 10 open-topped enclosures measuring 40 feet wide and 32 feet tall built on a 20-acre bog on the Marcell Experimental Forest. Climatic and hydrologic data have been collected at monitoring stations on the Marcell since 1960. This provides a unique set of baseline data for scientists as they manipulate conditions in the chambers to simulate a variety of hypothetical climate change scenarios and record a range of effects.
- Paul Hanson, Oak Ridge National Laboratory, U.S. Department of Energy