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Research

Arctic Meltdown Turns Up the Heat

6.23.17

 

Photograph by Bernhard Staehli/iStock


 

Photograph by Bernhard Staehli/iStock

At the Harvard Paulson School of Engineering and Applied Sciences (SEAS), researchers have found that rising temperatures and thawing permafrost in the northern region of the Alaskan tundra are leading to increased emissions of carbon dioxide into the atmosphere—as much as a 70 percent increase in such emissions since 1975. CO2 traps heat, acting like a blanket that keeps the earth warm, an effect particularly noticeable at night and in the winter. “It’s not so much an issue of it’s getting warmer,” said lead researcher Roisin Commane, “but that it’s not getting cold enough in the wintertime.”

The study is the result of a joint effort by SEAS, NASA, and the National Oceanic and the National Atmospheric Administration (NOAA). Between the months of April and November of 2012, 2013, and 2014, researchers deployed specially equipped aircraft (flown by NASA’s Carbon in Arctic Reservoirs Vulnerability Experiment, CARVE) to supplement on-the-ground observations of the changing conditions. The ground observations were made from NOAA towers in Barrow, Alaska, where temperatures have been rising twice as fast as in the rest of the region. The researchers also examined 41 years’ worth of carbon-dioxide emissions data NOAA had on file from Barrow. With regard to this multi-pronged long-term method to document and analyze carbon emissions, Commane explains that “the towers can tell if the carbon dioxide is coming out of the soil and going into vegetation. We needed aircraft because the ground towers only gave us a limited view in terms of radius, and we needed to know what was happening across the state.”

Soils in the Arctic are unique because they hold high concentrations of carbon trapped inside frozen layers. Typically, the upper layers thaw during the summer, which allows microbes to work away at the newly exposed soil and decompose the organic matter. In doing so, the microbes help release the carbon dioxide previously frozen within the soil. This soil contains enough carbon dioxide to double the current concentration of CO2 in the earth’s atmosphere, which is why it is imperative, the researchers say, that only the upper layers thaw and then refreeze in the space of roughly one month. Based on the SEAS team’s observations, that refreezing process is now taking up to three months, and Commane says it is very possible the duration will grow even longer in the coming years.

After pointing out that the tundra soils are acting essentially as an amplifier of climate change, Commane cites other dangers of the thawing permafrost: “Layers that had not thawed for thousands of years are now thawing. In Ireland, we use this kind of soil [peat] as a fuel source, which should give you an idea of some of the dangers of exposing this matter.” She notes that the number of fires in the region have risen between 2015 and 2017, and the rise in temperature contributes to a dry climate that is perfect for wildfires. Because the northern tundra region is fairly remote, the fires often burn without human interference, unless there is a risk of flames spreading to populated areas. Commane anticipates that there will be more tundra fires in the years ahead, which are likely to further pollute the air and release even more carbon dioxide into the region’s atmosphere.

Aside from their clear relevance to climate change, the findings published by Commane and her colleagues also pose serious questions for colder parts of the world beyond Alaska, such as Canada and Siberia. The popular image of Siberia as a “gateway to hell” is caused by a similar thawing in the permafrost soil there, which (unlike the soil in Alaska) has ice wedges in it. The melting therefore causes the ground to collapse, opening ominous-looking craters in the earth. Unfortunately, much about the soil structure there is unknown due to a lack of funding for research in the region, as well as difficulties in taking measurements of carbon and other atmospheric gases. Although Siberia might be a challenging next step for research, Commane and her colleagues are already hard at work on NASA’s Arctic-Boreal Vulnerability Experiment, which will enable them to examine further the atmospheric conditions in northwest Canada and Alaska.   

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