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Scientists in Alaska race to understand thawing permafrost

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  • Updated: May 31, 2016
  • Published September 20, 2015

FAIRBANKS -- Until recently, climate models, which predict everything from sea level rise to temperature increase, have largely ignored or glossed over permafrost, one of the largest stores of carbon on the planet. That's because data on the temperature of permafrost and the thickness of the active layer of soil that lies above the frozen ground were neither centralized nor available in a format modelers use.

That's about to change.

Heeding a long-standing call from fellow climate scientists, a global team of permafrost researchers last week announced a new comprehensive database on ground temperatures and thawing.

"The climate modeling community has always been pushing us, 'when, when, when,'" said the head of the Global Terrestrial Network for Permafrost -- and University of Alaska Fairbanks professor -- Vladimir Romanovsky, following the release of an article in the Earth System Science Data portal detailing the new initiative.

He added that out of the 25 leading climate models, only a handful have "assessed permafrost properly," using the limited data that was available.

"With the recognition that permafrost can be a source of greenhouse gases, it's important to (represent it) in the models more adequately," Romanovsky said.

The Global Terrestrial Network for Permafrost was to formally present the new data portal at a conference in Quebec, Canada, over the weekend.

An ominous -- and invisible -- problem

Ever since modern roads and buildings were introduced to the coldest regions of Alaska, scientists and engineers have been grappling with the problem of thawing permafrost.

The transfer of heat from a poorly built structure to the ground below can cause localized thawing and lead to a collapse. The slightest rise in air temperature can have widespread effects on the ecology of an area underlain by permafrost. These consequences, while difficult to address, are mostly easy to see.

But the new permafrost data portal highlights the more ominous -- and invisible -- problem researchers are increasingly confronting: the bubbling up of carbon dioxide and methane as result of thawing soil. Since permafrost contains vast stores of carbon -- double the amount currently found in the atmosphere, according to some estimates -- scientists fear that its thawing will enhance the greenhouse effect and lead to more warming.

President Barack Obama raised the concern in his recent climate change address in Anchorage, saying that, "when the permafrost is no longer permanent … the Arctic may become a new source of emissions that further accelerates global warming."

But behind the increased attention to permafrost lies the complex question of trying to more accurately predict its effects on carbon levels in the atmosphere.

"There's competition between different disciplines about (whose subject area) will drive the carbon release" as the climate warms, Romanovsky said. Contenders include oceanographers, glaciologists, bog limnologists -- and geocryologists, a term sometimes referring to permafrost researchers.

"Everyone thinks that what they are studying is the most important," said the Russian-born holder of two Ph.Ds. "But probably, everything is a factor."

Romanovsky's faith in cross-discipline research is reflected in his appointment last month to head a U.S. Department of Energy initiative to coordinate field work related to terrestrial hydrology, permafrost, vegetation, microbiology and biogeochemistry.

Even as Romanovsky takes on new leadership duties, he continues to work in the field, collecting information -- in particular, temperature measurements -- that will be made available in the new public database.

To determine long-term trends in permafrost, researchers seek out data from the coldest places, where the seasonal and annual fluctuations are flattened out.

Some of the best such measurements come from Alaska's North Slope, where Romanovsky travels every summer to measure temperatures deep underground. He uses holes as deep as 65 feet that were drilled decades ago at a number of locations near Prudhoe Bay and are monitored continuously.

The data from the last 15 years at those locations shows ground temperatures have warmed by a fraction of a degree, enough to indicate a larger trend, according to the 2014 State of the Climate report published by the American Meteorological Society.

"Permafrost warming in northernmost Alaska exemplifies what is happening to permafrost temperature on a pan-Arctic scale," the report said, summarizing the work of an informal network of permafrost monitors from the past year.

Romanovsky recently returned from the 2015 measuring tour on the North Slope and said the warming he'd previously observed is continuing.

In contrast with terrestrial permafrost in Alaska, which has been studied closely for years, one of the least-understood areas of permafrost research involves the thawing of frozen seabed in the Arctic, in particular off the coast of Siberia where worrying levels of methane venting have been measured. Prone to seasickness, Romanovsky has been forced to avoid this evolving area of research.

A warming North, in microcosm

As scientists pursue the goal of global, long-term permafrost monitoring, they're also conducting field experiments that simulate future warming.

A patch of tundra 185 miles south of the Arctic Circle near Denali National Park is especially well-suited to such research. The permafrost in this region is patchy and thin, with a temperature of around 30 degrees, only two degrees below freezing. Scientists here are inducing thawing and measuring the subsequent release of carbon.

Postdoctoral researcher Marguerite Mauritz, from Northern Arizona University, runs day-to-day operations at the Carbon in Permafrost Experimental Heating Project here, working with Edward Schuur, a professor of ecosystem ecology at the university, who visits the site several times a year and is considered one of the leading permafrost experts in the world.

"We may see changes here that could help predict changes at higher latitudes," Mauritz said.

The outdoor laboratory is located near a dirt trail off the Parks Highway.

From the trail, tiptoeing along a pathway of wooden beams for a few hundred feet brings researchers and visitors to a collection of scientific gadgets arranged on the tundra.

The concept of artificially warming the tundra might conjure images of vents releasing hot air, but the researchers use simpler and more natural means. In some spots, for example, they have built fences that cause extra snow to accumulate in the winter. Increased snow cover traps heat and warms the ground. Other sections of the tundra are left alone, as a control.

Mauritz's most basic tool is a metal rod with a pointed tip. She routinely bores the measuring stick through the active layer of thawed soil and vegetation until she reaches the thud of frozen ground below. Meanwhile, automatic sensors, inside what are called CO2 flux chambers, measure the circulation of carbon on an ongoing basis.

The main purpose of the experiment, now in its fourth year, is to understand whether the carbon emissions from decaying plant matter will be offset at all by the growth of new plants. "Plants grow very well in the thawing soil because there are a lot of nutrients," Mauritz said.

An initial study published from the data gathered here found that carbon trapped by new plant growth balanced out the carbon released from microbial decay -- but only in the summer. When factoring in the winter carbon emission, the ecosystem experiences a net loss.

The experiment needs further monitoring because "plant growth is not unlimited," she said. "How long can the increased carbon uptake by the plant growth offset the carbon loss due to thawing?"

An even more novel area of study for permafrost carbon researchers is analyzing the chemical fingerprint of emissions using what's called the stable isotope technique to tease out the carbon dioxide released from the microbial activity in the soil from the respiration of plants, which also release some carbon dioxide.

The threat from fires

In addition to warming the permafrost directly, climate change can also contribute to thawing in a more complicated way: in the effects from intense wildfires.

A study from last month compared wildfires in Alaska since 1930, analyzing fire severity alongside annual weather data and permafrost measurements.

Severe fires are defined as ones that burn to some degree through the organic mat of vegetation that insulates the permafrost below, and the loss of that insulation can cause thawing over time.

In the past, when the climate was cooler, permafrost was more likely to survive the loss of the organic layer, the University of Alaska Fairbanks study found.

"In the 1930s, a high-severity fire would have a big impact on permafrost but a moderate-severity fire would not," said lead author Dana Brown, a doctoral student at the university. "Today, even a moderate-severity fire would have a big impact. Permafrost has become increasingly vulnerable to the effects of fire due to changes in climate."

And long, intense fire seasons in Alaska's boreal forests are increasingly becoming the norm, according to scientific models.

As a graduate student, Brown has entered permafrost research at a time of increased public attention to human-caused climate change.

That was not the case when Romanovsky, one of her advisers, began his work in 1976. Then, interglacial transformation drew permafrost researchers' attention.

"What was exciting to us then was long-term change on scale of thousands of years but the research was not applicable to everyday life," Romanovsky said.

These days, the changes that researchers are interested in are happening much faster -- faster, it sometimes seems, than the ability to study them. That's one reason why tools such as the new publicly accessible and up-to-date permafrost database are so important.

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