Burning Questions

May 17, 2010

Scientists Seek Information from the Anaktuvuk River Fire

By Emily Stone

Journalists visited the site of the Anaktuvuk River Fire last summer. The charred tussocks were still visible beneath the blooming cottongrass. Photo: Lisa Jarvis

Gaius Shaver has been traveling to Toolik Field Station for 34 summers to study how tundra ecosystems react to small environmental changes. One of his experiments involves building greenhouses over 8-by-16 foot plots of land to gauge how plants react to warmer soil.

His research has yielded interesting results over the years, but there’s always been a question of how well that data would translate over large tracks of land.

Suddenly, Mother Nature gave Shaver and many other Toolik scientists a way to find out.

A massive fire burned about 400 square miles of tundra along the Anaktuvuk River from July to October 2007. It was the largest tundra fire ever recorded on Alaska’s North Slope. Now the scientists are studying how the area, which is roughly the size of Cape Cod, responds. In addition to examining the warming soil and plant changes, the group is looking at how much carbon was lost in the fire, the ongoing exchange of carbon between the land and air, and how melting permafrost is affecting rivers and streams. They’re finding that the fire has had a significant impact in all these areas. And given that continued warming in the Arctic will likely lead to more lightning which will lead to more fires, these are important questions to answer.

The 2007 Anaktuvuk River Fire burned a Cape Cod-sized section of the North Slope. Scientists are interested in how long it will take the area's plants and soil to recover. Photo: Adrian Rocha

“There’s a lot going on,” said Shaver, a senior scientist at the Marine Biological Laboratory who is leading the National Science Foundation-funded, three-year study that includes nine senior collaborators and a couple dozen other researchers. “It’s very exciting.”

The group calculated that the fire burned more than two million tons of carbon that had been stored in the soil, or roughly 25 years worth. This equals about 10 percent of the annual carbon emissions for the city of Boston. The fire also burned between 300 and 1,000 years worth of nitrogen.

The group is also interested in the continued changes in carbon exchange between the soil and atmosphere. Using instruments set up on three towers in the burn site, they’re measuring the exchange of carbon during the summers. If plants photosynthesize more than they and the soils in which they grow respire, then the net result is carbon being removed from the atmosphere. If there’s more respiration than photosynthesis, then the opposite is true.

Overall, the burned areas have a net carbon loss from the soil, meaning more carbon is being released into the atmosphere than at unburned spots. The researchers calculated that in 2008, the fire accounted for a minimum 2.8 percent reduction in the amount of carbon being taken out of the atmosphere across the North Slope even though the Anaktuvuk River Burn accounts for only 0.55 percent of the North Slope’s area.

The researchers know from older fires and erosion scars that shrubs tend to dominate the landscape after a disturbance at the expense of mounds of tussock grasses, which cover much of the North Slope. This seems to be playing out at the Anaktuvuk River Burn. Although shrubs were knocked back dramatically by the fire — even more than the tussocks — they are recovering rapidly even in severely burned areas and may soon exceed the grasses in the amount of ground they cover. 

Undisturbed tundra tends to keep its plants in pretty consistent ratios as they compete for limited resources in the soil. “A disturbance shakes up those relationships among species,” Shaver said. This is important because shrubs tend to insulate the soil in the winter, keeping it warmer, and also hold less carbon below ground than tussocks do, both of which can further change the landscape.

Another striking discovery is the change in albedo, meaning the percent of the sun’s radiation that is reflected away from the ground. In the first summer after the fire unburned portions of the burn site had a 17 percent albedo while severely burned sections had a 3.5 to 4 percent albedo. That means an additional 13 percent of the sun’s radiation was being absorbed in those areas. And that heat has to go somewhere, often warming the soil to higher temperatures and permeating deeper than normal. This difference was less in 2009 than in 2008, and Shaver said it will eventually return to the level of unburned tundra. 

Data show that burn scars absorb more of the sun's radiation than unburned tundra, increasing soil temperatures. Photo: Adrian Rocha

In the meantime, increased heat flux into the ground can cause thermokarst failures, which occur when the ice that’s normally frozen solid in permafrost melts and the land above it collapses like a soufflé. Last summer the group noticed more and more of these depressions as the season continued. When thermokarst erosion happens near streams and lakes, it dumps extra nutrients into the water, giving microbes, plants and fish access to more food and thus changing the aquatic ecosystems. 

“We can’t make a treaty to stop thermokarst and fires,” said Syndonia Bret-Harte, an associate professor at the University of Alaska Fairbanks, who is heading up the plant studies at the burn.

Bret-Harte, who is also Toolik’s associate science director, was at the station in 2007 while the fire was burning about 25 miles away and at times could see a wall of smoke in the distance.

“It was awesome and beautiful, but disturbing at the same time,” she said.

Once the scientists realized how big the fire was, Shaver applied for an NSF grant for the following summer, knowing how valuable the natural experiment would be for the scientists at Toolik, many of whom are part of an ongoing Long Term Ecological Research Project, one of 26 in the U.S. LTER network.

The group is adding a component to this summer’s research by visiting the sites of two large fires from 1993 to see how they’re recovering in hopes of predicting how the Anaktuvuk River Burn will fare in the coming years. They’ll take measurements to see, for example, how much soil has accumulated above the char level and what the diversity of plant species is like.

All of this is crucial information to have as more and more disturbances like lightning-driven fires and thermokarst occur across the Arctic.

“Overall climate change is gradual and the overall response to this change is gradual,” Shaver said. “But then we have these patches of intense change and the patches may be changing so intensely that from the perspective of the whole North Slope, they actually dominate the overall changes.”


To Inuit, Sea Ice Means “Freedom”

May 13, 2010

  

At the edge of the sea ice, a Barrow resident awaits the return of a seal-skin whaling boat. Photo: Faustine Mercer

Here’s a really interesting story on Shari Gearheard’s NSF-funded people and sea-ice study. Gearheard, a glaciologist from U Colorado’s National Snow and Ice Data Center, combined scientific sea-ice studies with the traditional knowledge of Inuit collaboraters who’ve spent their lives on or near the ice.  The aim: to gain a better understanding of how sea ice is changing in the Arctic–and how community lifeways around the Arctic may be changing in response.  

Gearheard and her collaborators speak extensively in the piece, and what they have to say about the changes they’ve seen in sea-ice conditions is compelling.   

“‘I’m a scientist so when I look at sea ice I see what its properties are. How dense it is. But I remember sitting with the hunters when we were all in Qaanaaq. They looked at the sea ice and the first thing they said they saw was ‘freedom’.  

‘(Sea ice) meant they could hunt for food. It meant they could travel to see relatives on the other side of the water, that they hadn’t seen all year.  

‘That was a very powerful thing for me as a person, not just as a scientist.'”–Shari Gearheard  

* * *

“‘When I was a boy, the ice used to hover around Barrow all year,’ 51-year-old Leavitt said. ‘Now when the ice takes off it doesn’t want to come back. So our hunting is very limited.'”–Joe Leavitt, Barrow resident and whaling captain  

* * *

“‘We used to live as nomads in those days,” Sanguya continued. “After Christmas, when there was enough snow, we’d go out on the sea ice and make igloos.  

‘In those days I didn’t have any math or measurements … or anything like that. But I remember looking down through seal breathing holes and the ice was so thick, they looked like they were tapering away.  

‘Today you don’t see that very much. You’ll probably see 4 feet or 5 feet (down) and that’s it.'”–Joelie Sanguya, Elder and hunter, Clyde River, Nunavut

Hunters in Qaanaaq, Greenland traditionally travel over the sea ice on dog-powered sledges like these. Photo: Hans Jensen


GrIT: Circumzenithal Arc

May 7, 2010

Parahelia with circumzenithal arc. Greenland ice sheet, May 6, 2010. Photo: Robin Davies

From Robin’s email:

“I got this shot yesterday afternoon, as we reconfigured the Tucker load (which is why the outhouse is in the frame). As the cloud thinned and the sky got bluer, the sun halo and sun dogs that had been coming and going for some time  suddenly developed a Circumzenithal Arc (the inverted rainbow above the sun), which sent me scrambling for my camera.

“I’ve been trying to get a good shot of one of these ever since I’ve been coming to Greenland and now I’ve got one with an outhouse in it!”


Coring Around Cordova

March 11, 2010

If all goes according to plan, Darrell Kaufman is coring lake sediments in southern Alaska. Of course, hardly anything ever goes according to plan.

Darrell Kaufman

One of the busiest researchers we know, paleoclimatologist Darrell Kaufman from Northern Arizona University, has started a long research season with a truck and snowmachine trip in southeastern Alaska’s Copper River Valley. He travelled there earlier this week to core a couple of lakes around Cordova.

After flying in to Anchorage a few days ago and picking up a truck with a trailer and two snowmachines, Kaufman and team drove down the gorgeous Richardson Highway to Valdez, and then travelled by ferry over to Cordova—or such was the plan. The Valdez area has received over five feet of snow in the past few days, but we suspect Kaufman’s team had already reached Cordova before the storm hit, and that all is proceeding roughly according to plan. Basing in Cordova, they will use snowmachines to travel to nearby lakes, still capped with winter ice—or so we hope. In this El Nino year, there’s been speculation that lake ice might be a bit thin.

The plan is to set a small drilling rig on the frozen lake and then to bore a hole in the ice in which to deploy the sediment coring equipment.  Cores harvested from the lake bottoms will be shipped to the Kaufman lab at NAU for analysis. Researchers will look for evidence in the sediments–tiny bugs, pollen spores, and dust, for example–that they can use to understand what climate was like when the particles drifted down to the lake bottom.

A Kaufman researcher examines deformed sediments pulled from beneath Tonsina Lake (one of the lakes Kaufman plans to revisit this trip). Photo courtesy D. Kaufman Web site: http://jan.ucc.nau.edu/~dsk5/

As we mentioned, Kaufman is busy this year. He’s leading a giant international collaboration of scientists who are looking at lake cores to better understand how unusual events, say, large volcanic eruptions, can trigger abrupt changes in climate—and what those abrupt changes look like in the sediment record, as well as what types of climate phenomenon may follow.  Understanding the “signatures” these events leave can help scientists improve the models we use to predict future climate.

Kaufman will also work in the Brooks Range this summer with collaborator Jason Briner; and he’ll revisit Adak Island in the Aleutian chain and Allison Lake to collect more lake cores. 

We caught up with Kaufman to learn more about his work last fall. Click here to find out about lake core science—straight from Kaufman himself.

We discovered this recent Kaufman article in the Arizona Republic, a statement about the so-called “Climategate” folly resulting from illegally-obtained emails.


Polar Bear Encounters on Baffin Island

February 1, 2010

On the hunt for clues to past climate, he found polar bears—and they almost found him.

Before the threat of polar bears sent them into cabins, graduate students Kurt Refsnider and Chance Anderson camped out on Baffin Island in tents during summer field work. All photos: Kurt Refsnider

Research Adventures

When University of Colorado PhD student Kurt Refsnider headed north last summer to collect samples for Gifford Miller’s NSF-funded paleoclimate study, he knew what to expect. He’d already spent parts of two summers exploring the remote, wind-swept reaches of Baffin Island in Canada’s High Arctic, searching for evidence of ancient glacial movement.

He knew that a researcher’s best-laid plans were subject to out-of-nowhere storms or shuffling helicopter schedules.  So the first few weeks of the trip he made in 2009 along with graduate student Chance Anderson proceeded largely as expected (if not exactly as planned). Outfitted with tent-camping gear and their sampling equipment, they were transported to the field by helicopter.

“We flew into Pond Inlet on the northern end of Baffin Island,” Refsnider recalled in a recent email.  “We then were moved into the interior of the island by helicopter and spent several days in a particular area before being moved again to a new site.  Bad weather, which kept the helicopter from reaching us during the last two weeks, forced us to stay days longer than planned at two camps.”

Looking for ancient climate clues at the top of the world.

When the weather cleared, the team moved south by helicopter to the Qivitu region. As planned, locals from the community of Qiqiktarjuak helped with logistics.

“We hired two guides to take us by motorized canoe to the Qivitu Peninsula, and we brought one ATV with us to get around once on the peninsula,” Refsnider wrote.  When they reached their study sites, “We set up a camp there, including a trip-wire alarm system due to the presence of bears in the area.”

It beats walking. Getting a ride from a local in a motorized canoe.

Retracing Ancient Ice Sheet Movement for Clues to Past Climate

Miller’s team is analyzing glacial deposits (rock and sediment samples) for information about how ice sheets formed in ancient times, waxing and waning in response to climate change. A few glacial deposits in the area go back about two million years, a rare commodity in the Arctic. Back in their labs, scientists use a variety of high-tech measurements to extract information about the evolution of the ice sheet.  The information should help them better understand long-term patterns in glacial erosion, test a key hypothesis for the cause of a major shift in global climate cycles that occurred around a million years ago, and lead to improvements in ice sheet models.

In addition to these goals, the team was collecting samples of moss and lichen from beneath the edges of rapidly-disappearing ice caps on the interior of Baffin Island.  These ice caps formed in the past few thousand years in response to climatic cooling.   Due to the cold arctic climate, the ice was frozen to the landscape, leaving the old moss and lichen intact.  Radiocarbon dating of this organic material provides a record of precisely when these ice caps formed, allowing Miller’s team to evaluate both potential causes for and the rapidity of this cooling.

Wild Kingdom

Daily polar bear sightings like the one here drove the researchers into hard-walled cabins at night.

The researchers spent a few nights camping, but daily sightings of polar bears—four or five sightings a day, in fact–convinced them to retreat to plan B: to use small cabins that dot the area owned by locals who use them during hunting trips.

The researchers broke camp and drove the ATV to the cabin, a rudimentary structure with boarded-up windows that nevertheless felt like a safer option than the tent camp.  That’s ironic given what came next.

“The first night there, at one or two in the morning we were awakened by a crash on the wall, which was followed by probably five minutes of clawing, scraping, and pounding on the far end of the weak little structure,” Refsnider wrote.  “We stomped and yelled, trying to scare the bear away, but we must have smelled pretty dang good.  The thought of shooting at the bear through the wall crossed my mind, but then there would be a hole for the bear’s claws to tear at, so I just waited, hoping the interior wall didn’t fail.  Eventually the bear gave up, left the mud room, dug briefly around the back of the cabin, and then apparently wandered off.”

The damage done: a polar bear-destroyed mudroom.

The next day, the team flagged down a passing motor canoe and returned to the safety of Qiqiktarjuak to regroup.

“A few days later,” Refsnider continued, “We spent one night at a guide’s cabin 50 km to the south.  As we approached it up the fiord in the guide’s boat, he noticed the front door had been smashed in.  While no one had been there, a bear had broken down the front door, torn up everything inside the mud room, and then left, again without getting into the main part of the cabin.  Our guide, who had been doing this for 50-plus years, was visibly shaken by this.”

Close Encounters of the Unusual Kind

Though polar bear sightings are common in the area, these close encounters with aggressive bears are not. Refsnider’s advisor, PI Gifford Miller, has spent many seasons working on Baffin Island in the company of polar bears, but none of his stories compare to the events of 2009. The reaction of the community to these events speaks volumes, as well:

“The residents in Qikiqtarjuak were amazed by what was happening.  The sea ice had melted/blown out of the area six-plus weeks earlier than normal, so the bears started coming back onto the land far earlier than normal,” Refsnider explained.  “That means they are much hungrier in late August than normal.  The day after we left, the town put two armed guards on patrol 24 hours a day because of the high number of bears in the area.  This had never been done before.”

The bear encounter wasn’t the only unusual experience the researchers had last summer. They also witnessed dramatic thunderstorms, which “are becoming increasingly common on Baffin Island,” Refsnider said. ”We had five days in a row early in the field season with convective thunderstorms blowing up over the central part of the island, most days with cloud-to-ground lightning!  Inuit are surprised by this, and 30 years ago they heard thunder so rarely that some believed that there was one thunder that slowly circled the globe.”

Back to Baffin

The team will return this summer to Baffin Island to finish the sampling, but with increased precautions to limit their exposure to polar bears.  They will base in Qikiqtarjuak, flying between the village and their sampling sites via helicopter, and returning at the end of the day to the safety of the small community. The helicopter will stay with them at the sampling sites. The research team will be accompanied by local guides who stand watch for bear as the team works.

Refsnider says he’s recently heard from his contacts in the village. In an unprecedented turn of events, the sea ice drifted away in December. This means that it is likely the polar bears will find little sea ice on which to stage their hunt for food again this spring and summer—which may increase the likelihood that they will again approach human settlements to find food.

“We’ll be much better prepared to deal with the potential bear risk with several additional armed guides, a helicopter, and more secure place to spend the nights, but I’d be lying if I said I wasn’t still a bit nervous,” Refsnider admitted.  — Kip Rithner


On Frozen Ground

January 27, 2010

Dr. Vladimir Romanovsky, director of the Permafrost Laboratory at the University of Alaska, Fairbanks, conducts permafrost research on the North Slope of Alaska. Photo: courtesy Dr. Romanovsky

By Marcy Davis

Scientists have long known the importance of permafrost, a layer of frozen soil in circumpolar regions that is one of the first victims of a warming climate. For more than 50 years, researchers have dropped temperature sensors into boreholes at various depths all around the world to track the state of the permafrost. But much of this data remains isolated and unpublished, inaccessible to anyone hoping to track global temperature change.

But if Dr. Vladimir Romanovsky, director of the Permafrost Laboratory at the University of Alaska, Fairbanks, Geophysical Institute, has his way, an international collaboration between the United States and Russia could produce the first international permafrost network. Call it the Cold Cooperation, the scientific opposite of the Cold War.

Linked In

As one of 35 National Science Foundation-supported Arctic Observing Network (AON) projects, Romanovsky’s work will integrate 80 Alaskan borehole sites—locations where researchers study permafrost, with about 160 Russian borehole sites. This initial step will provide the baseline temperature estimates necessary to evaluate future rates of change, according to Romanovsky.

“Permafrost data is beneficial to any ecological or carbon cycle study,” said Romanovsky. “Providing our data to other studies is important. In turn, we want to know about ecosystems, and have to be able to take into account hydrology and vegetation changes. Establishing this network will facilitate better communication and data sharing.”

Improved Modeling

In addition, the network will make permafrost data more available to climate modelers, which should improve researchers’ abilities to predict and understand the interaction between permafrost and climate.

Permafrost

Permafrost, defined as any earth material at or below 0°C for two or more consecutive years typically forms in the Arctic, subarctic, Antarctica, and in high alpine regions. It can vary in extent and thickness, and the largest area of continuous permafrost underlies the Tibetan Plateau in China with an area totaling 2.5 million square kilometers, more than twice the size of Alaska. Eastern Siberia holds the record for thickest permafrost at 1400 meters.

Domestically, permafrost in the Rocky Mountains of North America is laterally discontinuous, or patchy, with thicknesses ranging from less than one to several meters. Where temperatures are consistently colder, the permafrost is thicker.

Along Alaska’s North Slope, permafrost is continuous except under big lakes and rivers, which do not freeze completely to the bottom in winter; water acts as a source of heat to the ground below. At Prudhoe Bay, permafrost is 660 m thick. In Alaska’s interior, permafrost is discontinuous, found mostly in stands of black spruce and in low valleys where moss and peat are prevalent; Aspen groves and south-facing slopes rarely have permafrost.

Changes To Frozen Ground

Romanovsky has observed temperature changes in Alaskan permafrost, but added that interpreting those changes is difficult. Natural oscillations that last multiple decades show the same patterns; researchers need more time to understand whether or not their results result from longer-term, global climate change.

“The cycle seems on an upward trend,” he said. “What we see could be global warming, or could just be a longer natural oscillation. What are interesting are the hemispherical similarities between Alaska and Russia. Models can help explain past temperatures and future projections regionally and globally. So, we need to keep making measurements.”

Threats To Permafrost

One of the biggest concerns about warming permafrost is that greenhouse gases such as methane now sequestered in permafrost may be released back into the atmosphere, thereby creating a positive feedback for future climate warming. Another worry stems from the potential impacts of thawing permafrost on the communities, which could include localized but important changes in ecosystems and infrastructure.

Romanovsky says, “We are seeing changes in permafrost, but they are slowly evolving changes. There could be dangers for people who live in permafrost regions so they should be aware of the problem, but should not panic. Instead, we need to focus on mitigation, and working together. We have some ways to tackle these problems, but it takes time and money.”


Arctic Stories: New Multi-Media Web site

January 21, 2010

Not your typical office. A research building at Barrow, AK. Photo courtesy Arctic Stories

We’re pleased to welcome Arctic Stories, the brainchild of Purdue University atmospheric chemist Paul Shepson, to the online effort to educate and inform people about arctic research and life. (In 2009, we supported Shepson and others working at Barrow, Alaska, on an international study called OASIS. Shepson headed an NSF-funded study of halogen chemistry.)

With children’s book author Peter Lourie, Shepson has built a multi-faceted Web site with NSF funding to present information on the science, wildlife, climate, and people of the Arctic.

The site features video interviews with natives and researchers like polar bear researcher Steven C. Amstrup of the USGS. It also showcases compelling photographs, and links to science institutions. In short, it’s another fantastic resource for following the ongoing work in the Arctic.

This is helpful as the public strives to understand the myriad messages about climate change, research, and more. With news stories reporting that the Arctic is warming twice as quickly as the rest of the planet, that sea ice is melting, and that species are losing habitat and nourishment, sites like Arctic Ice and ours aim to inform readers about the efforts being made to understand the science behind the phenomena.

The science is complex, designed to measure and help us understand changes in the atmosphere, land, plants and animals, human societies and water in the Arctic. To advance these goals, scientists conduct fieldwork in some of the most extreme environments on Earth–and their experiences are often as compelling as their data.

We encourage readers to check out Arctic Ice as they follow their curiosity about work in the far north.