Welcome to a Warmer Future
By: Austin Yantes
Edited by: Katherine Hill
Walking through the grounds of the SPRUCE experiment feels a bit like exploring a foreign planet. Unusually small tamarack and black spruce trees pepper the landscape, their growth stunted by the harsh conditions of the peat bog. Among them, ten 26-foot-high translucent, cylindrical chambers tower over a metal boardwalk. Above one of the chamber doors, an ominous sign reads “Welcome to a warmer future”.
Spruce and Peatland Responses Under Changing Environments (SPRUCE), located in north-central Minnesota, is a large-scale climate change experiment. To mimic potential future climate conditions, the temperature in the chambers are raised to +0°C, +2.25°C, +4.5°C, +6.75°C, and +9°C above the outside temperature, under both ambient (+0 parts per million) and elevated (+500 parts per million) carbon dioxide. Scientists have set up a diverse collection of monitoring equipment to gather information on the water, soil, air, and plants inside each of the chambers. From the data, they hope to gain an understanding of how northern peatland ecosystems will respond to climate change [1].
The main driver of climate change is greenhouse gases in the atmosphere, such as carbon dioxide (CO2), which trap radiation from the sun and cause the planet to warm [2]. Humans produce CO2 by burning fossil fuels (coal, gasoline, natural gas etc.) for daily activities such as transportation, heating, and agriculture. So what does this have to do with a giant, space-age looking experiment in the middle of a bog? Believe it or not, northern peatlands play a major role in climate change.
Peat is basically a mixture of decomposing plants, and plants contain a lot of carbon. Since the boggy environment is saturated with water and devoid of oxygen, the organic material in the plants can’t fully break down. As a result, the material builds up over millennia, and the carbon that was once held in the plants becomes trapped within the peatland. By storing CO2, peatlands prevent the gas from contributing to global warming. And although peatlands cover only a tiny fraction (3%) of the Earth’s surface, they hold the equivalent of half the carbon in the entire atmosphere [3]. In fact, peatlands store up to 500 billion metric tons of carbon — more than any other ecosystem [4,3].
While peatlands store CO2, they simultaneously release a different gas — methane (CH4). Like CO2, methane is a greenhouse gas which means that it also contributes to global warming. Historically, the cooling effect of trapping and storing CO2 has far outweighed the warming effect of emitting methane [3]. However, as the climate continues to change at an unprecedented pace, this may no longer be the case.
Using the large chambers at the SPRUCE facility, scientists from Boston University have revealed new information on how peat bog ecosystems respond as we turn up the heat. Specifically, they looked at how warming deep below the ground — a phenomenon with the catchy name “Deep Peat Heat”– affects methane and CO2 fluxes at the surface. To heat the peat, they installed a total of 67 low-wattage heating elements, placed vertically in concentric rings within each of the chambers. They found that emissions of both methane and CO2 increased with the Deep Peat Heat treatments, and the warmer the treatment, the stronger the response. As the peat got warmer, more and more of the carbon being released was in the form of methane, which is the stronger, more potent greenhouse gas [5].
Here’s where it gets scary — this sharp increase in methane emissions may be enough to destroy the long-standing balance between CO2 storage and methane production. As peatlands begin releasing the CO2 they’ve been holding on to, and emit progressively more methane, they may have a net warming effect on the planet. This creates a vicious cycle — as the climate continues to warm, peatlands will release more CO2 and methane, and as peatlands release more CO2 and methane, global warming will accelerate.
Before making broad conclusions, it is important to remember that the Deep Peat Heat treatments were only applied over a period of 13 months. Nevertheless, the data collected from SPRUCE is consistent with the widely accepted view that these northern regions are likely to amplify ongoing global warming [5].
Tucked away in a nondescript stretch of Minnesotan forest, SPRUCE scientists continue to work diligently to understand what a warmer climate means for peatland ecosystems. They use the towering experimental chambers as a crystal ball — giving us a never-before-seen glimpse into the future of life on Earth.
References
1. Oak Ridge National Laboratory. SPRUCE: Experimental Design. Retrieved February 05, 2018, from https://mnspruce.ornl.gov/design
2. NASA. (2017, August 10). Climate change causes: A blanket around the Earth. Retrieved February 05, 2018, from https://climate.nasa.gov/causes/
3. Dise, N. B. (2009). Peatland Response to Global Change. Science, 326(5954), 810–811. doi:10.1126/science.1174268
4. Yu, Z., Loisel, J., Brosseau, D. P., Beilman, D. W., & Hunt, S. J. (2010). Global peatland dynamics since the Last Glacial Maximum. Geophysical Research Letters, 37. https://doi.org/10.1029/2010GL043584
5. Gill, A. L., Giasson, M. A., Yu, R., & Finzi, A. C. (2017). Deep peat warming increases surface methane and carbon dioxide emissions in a black spruce dominated ombrotrophic bog. Global change biology.
