UNH scientists decipher the impact of thawing permafrost

By Alison Eagan

The Arctic Circle, an area of five million square miles located across the northern reaches of the planet, is defined by a frozen foundation of rock, soil, and water known as permafrost. While the majority of permafrost lies within the Arctic Circle, there are millions of square miles that stretch beyond; in fact, permafrost covers 25 percent of all land mass in the northern hemisphere. Now, various communities who call the Arctic Circle and beyond home are at risk of that permafrost thawing, threatening infrastructure, natural resources, and cultural heritage.

In warmer soil, as organisms die, microbes come together and decompose the organic material. But in permafrost’s state of constant freeze, organisms do not fully decompose. So, the frozen layer serves as a vast carbon sink. It holds the equivalent of one-third of all the carbon already present in the atmosphere and absorbs more carbon each summer when vegetation is at its peak growth.

For years, scientists have concluded that global warming is thawing permafrost across the Arctic. According to a recent article released through the Earth Institute of Columbia University, the Arctic Circle is one of the most climate sensitive areas on the planet, and it is warming at twice the rate as temperatures 2,000 years ago.

Alison Photo
Sophie Burke collects methane samples in northern Sweden. (Photo: Ruth Varner)

 

So, as temperatures continue to climb, the Arctic can be expected to lose almost 1.5 million square miles of permafrost, and the results are alarming. Dead carcasses could release zombie viruses, ancient pathogens, and harmful greenhouse gases into the surrounding environment through watershed or the air that humans breathe.

The big question, according to Dr. Jessica Ernakovich of the Natural Resources and Earth Systems department at the University of New Hampshire, is how microbial communities like bacteria, archaea, and fungi within the permafrost will start to function as it continues to thaw. For Ernakovich and other Arctic permafrost researchers at UNH, the carbon cycle plays an essential role in understanding the function of these microbes, and the types of potential threats or benefits they pose to the existing ecosystems with increased thawing. The carbon cycle is the movement of atmospheric gases into plants, which convert that into carbon dioxide.

And as permafrost thaws, the earth could see an additional 1.7-degree Celsius temperature increase on top of the projected rise to two-degrees Celsius. In a recent report issued by the International Panel on Climate Change, temperatures are already rising faster than previously thought, so the release of carbon from the permafrost could pose additional threats to the Earth as a whole.

“The big unknown is just how much carbon is in that permafrost that would be released into the atmosphere,” said Katharine Duderstadt, an atmospheric researcher of the Earth Systems Research Center at UNH.

Duderstadt is one of a growing team of science faculty and graduate students racing to answer this and other key questions about the many unknowns within the thawing permafrost. These scientists are part of UNH’s broader Arctic research initiative.

According to their strategy for Arctic Research, UNH is organizing the research under two major themes: “Arctic Feedbacks: Humans, the Water Cycle, and Carbon Cycles,” and “Where People Live: Land-Coast Connections.” The university is already well known for its extensive research on Arctic sites and will continue to fund projects to answer new questions about the changing Arctic environment.

Natalie Kashi, a Natural Resources and Earth Systems (NRES) PhD student, is studying microbial communities within the permafrost. Throughout her graduate research, Kashi has been examining how peatland moss absorbs carbon during the carbon cycle.

She is looking at how the plants are photosynthesizing or absorbing all the carbon. If they aren’t absorbing it, it’s being decomposed by the microbes, which then turn the carbon into greenhouse gases like carbon dioxide or methane. Kashi hopes to discover what’s limiting these plants from absorbing the carbon. She says that if the carbon is not absorbed by the plants and microbes, it may be “absorbed by the stream networks which then feed out into the lakes, and the ocean.”

Peatland moss, otherwise known as a bog or a marsh, is the largest methane emitter within the Arctic ecosystem. The potential methane that could be released into the atmosphere as temperatures continue to rise is severe. This question is being studied by two other PhD students within the NRES doctoral program. Clarice Perryman and Sophie Burke are measuring trace gas biogeochemistry, or in layman’s terms, the methane that is absorbed or released by the plants in the peatland moss. “The green aliens in the peat that eat the methane are bacteria,” Perryman says. Ideally, the more bacteria, the better, as it could potentially reduce methane emissions by 20 to 40 percent, according to Perryman.

It is unknown how much bacteria is in the permafrost. Researchers are trying to figure out how microbial communities will respond as the ecosystem warms. “The goal is to find out what the net emission [of methane] is, and how that will change global atmospheric temperatures,” Perryman says.

Perryman and Burke have taken many samples from their field work in Sweden and are testing how the methane is being absorbed or released. When the researchers conduct their research in the Arctic, they spend weeks getting to know what will soon be lost. “What always strikes me when I visit the same site over the years, is the change in the landscape over a relatively short time period,” says Burke.

The northern Sweden landscape isn’t the only area experiencing drastic changes in recent years. Bianca Rodriguez-Cardona spends her “free” time running samples of the stream water she collected on a trip to the Central Siberian Plateau in July of 2016. Rodriguez-Cardona, also a PhD student within the NRES program, is testing the recently burned sites of the plateau and studying how the stream chemistry responds to the sudden change.

The Central Siberian plateau is beginning to see an increase in forest fires, as drier, warmer conditions put the organic carbon along the forest floor at risk of burning. The fire speeds the rate of the permafrost thawing. “It’s not melting; it’s thawing,” Rodriguez-Cardona adds. “It’s like when you heat up a lasagna in the microwave, the lasagna doesn’t melt and turn to liquid, it thaws out.”

Rodriguez-Cardona can tell how a fire affects the environment by running her samples of the local stream runoff. She can see a spike in nitrate and a decrease in carbon. These samples may tell Rodriguez-Cardona how this stream chemistry may affect larger bodies of water as the permafrost continues to thaw. “More nitrate can lead to algo-blooms and changes in the food web as it moves along the different bodies of water,” she says.

Stacey Doherty, another NRES PhD student, is beginning her research about the interaction of the microbes within the active layer of soil and the permafrost layer. The microbial community could potentially tell how the permafrost layer may look as it continues to thaw. These once frozen ancient microbial communities tell a story of what pathogens existed some 800 years ago, and if they could emerge again and pose a threat to the present environment.

“There’s so much we don’t know,” Doherty says.

According to recent research, she says, only between two and five percent of microbes within the active layer and permafrost match microbes in current data bases. However, Dr. Ernakovich says that number is probably much larThe Arctic is very understudied,” Ernakovich says. She is currently writing a paper that analyzes the knowledge gaps about the permafrost microbial communities. Her work and the students’ work may potentially contribute new information for global models in the future.

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