Update: Kaufman’s Coring Trip

Cascade Lake, Alaska, during a 2009 coring trip. Photo: Darrell Kaufman

Darrell Kaufman jotted an email last week to report that his team was back from a ten-day excursion to Cordova, Alaska, to collect sediment samples from a group of area lakes. Their field work went well. “We recovered over 350 lb of mud from four different lakes and discovered some really interesting new records of environmental changes,” Kaufman wrote. For more on Kaufman’s work, click here.

Coring Around Cordova

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.

Looking Back to Look Ahead

An Air Greenland helicopter arrives to return Jason Briner and his field crew to town after a month in the field studying the rocks and lakes around the Jakobshavn Isbrae. Photo: Jason Briner

As climate scientists attempt to forecast how increases in atmospheric temperatures expedite the melting of polar ice sheets, a team of paleoclimatologists is searching back in time for important clues on the effects of previous climate disruptions. Specifically, the team, led by Dr. Jason Briner (State University of New York, Buffalo), is studying Greenland’s Jakobshavn Isbrae to understand how climate changes during the Little Ice Age and Holocene thermal maximum—a time span of roughly 10,000 to 100 years ago—impacted the glacier’s behavior. Given that the most comprehensive data on the glacier span only about two to three decades, reconstructing the Jakobshavn’s response to climate change over a period of thousands of years will yield insights into the relationship between warming temperatures and glacial trends, said Briner.

“The intent of paleoclimatology is to see what the earth systems are capable of doing in longer time periods and in different climate regimes,” said Briner. “By looking in the past, we have the ability to know what happened when it was 5 to 10 degrees colder or warmer. We are trying to make our research relevant in the context of modern climate changes so we might better understand what might happen in the future.”

Working on the Jakobshavn also provides a unique opportunity to do paleo work on an existing glacier, said Briner.

Jakobshavn Isbrae: The World’s Fastest Moving Glacier

Jakobshavn Isbrae is considered the world’s fastest moving glacier. According to a recent article in the Financial Times, the Jakobshavn Isbrae is perhaps the fastest moving glacier in the world. It drains roughly 6.5 percent of the Greenland ice sheet, and has been documented to be moving at 13 km per year and pouring about 40 km³ per year of ice into the fjord.

In the past two years, Briner and his team conducted a National Science Foundation-supported pilot study to demonstrate the utility of analyzing the glacier’s past. Concentrating on the Holocene period, which began about 12,000 years ago, when average temperatures were about 3 degrees Celsius warmer than they are today, they attempted to identify more precise temperature ranges as well as to understand the glacier’s activity. They also collected information from the Little Ice Age, which followed the middle Holocene warm period and marked a cooling of the earth’s climate from about 600 to 100 years ago.

SUNY-Buffalo undergraduate student William Phlipps and graduate student Shanna Losee take core samples from a big pile of mud that formerly was a lake during the Little Ice Age. As the ice sheet advanced during the Little Ice Age, it blocked a river and created a lake. Once the lake was there, the river valley was buried by silty lake sediments. In the late 1980s, the lake drained out completely because the ice sheet (the lake's dam) retreated, and all the water spilled out. Photo: Jason Briner

Their data came from isotope analysis and radiocarbon dating of lake sediment, as well from three-dimensional maps created using historical photos and an assessment of the insect remains within their lake sediment samples. Although the team’s research focuses on the glacier itself, their detective work took place on the surrounding rocks and in the many lakes on the glacial moraine.

“We work where the ice was, not where it is,” said Briner. “Our geologic record comes from the landscape.”

Will Phlipps and Nicolas Young, PhD student, SUNY-Buffalo, hike along the crest of a moraine deposited during the Little Ice Age. In the distance is the iceberg-choked icefjord, which was occupied by the Jakobshavn ice stream during the Little Ice Age. The ice margin is now about 20 km away. Photo: Jason Briner

Lakes Rich With History

These lakes serve as conservatories of glacial debris, which drained into them when the Jakobshavn melted and retreated over time. Briner and his team study sediment cores from the lakes to date the contacts, which is how they confirmed the glacier advanced during the Little Ice Age.

“Until the Little Ice Age, the lakes had no glacial meltwater input,” said Briner. “The ice margin advanced during the Little Ice Age close to pre-existing lakes, but not over them.  In fact, it advanced just barely close enough that it spilled its melt water into the lake basin and ultimately the silt particles in the ice sheet melt water were deposited in the lake, which, prior to that, just had the organic sediments. When the glacier retreated, its margin receded back out of the lake’s drainage basin.”

Shanna Losee, Nicolas Young, and Will Phlipps on a coring platform on one of the lakes in the study area. Photo: Jason Briner

Putting the Puzzle Together

The team aims to reconstruct the climate and establish a more specific temperature record that spans the Holocene period. Currently scientists have a broad understanding of the average temperatures during the Holocene, but those temperatures varied significantly depending on altitude and location, said Briner.

“We are trying to get a record from our site and quantify the changes in ecology to get a local temperature record to see if it syncs with what the glacier was doing,” he said

The research at Jakobshavn is similar to research Briner and fellow scientists recently completed at the Sam Ford Fjord in Canada’s Baffin Island. Similar climate reconstruction efforts found that 9,500 years ago, the fjord’s kilometer-thick glacier melted in a “geologic instant” during a climate-warming period. Like the glacier in Sam Ford, Jakobshavn is sitting in a similarly deep fjord. Briner said the Baffin Island work revealed the significance of glaciers that lie in very deep water.

“When glaciers that calve retreat into deeper water, that promotes further retreat,” he said. “And that amplifies the retreat rate.”

The Jakobshavn is one of these glaciers; the calving front is in only 800 meters of water, but people who have done radar surveys discovered that most of Jakobshavn resides in a trough that is 1,400 meters below sea level. Once the Jakobshavn starts to retreat, it likely will continue retreating quickly, much like the glacier in Sam Ford did almost 10,000 years ago.

“With the Sam Ford, the glacier retreat was triggered by a warming climate,” said Briner. “This mechanism having to do with water depth was superimposed on the warming and made the response drastic. We reconstructed the relative instant disappearance of the glacier.”

That raises questions about the Jakobshavn. Specifically, when did it retreat in the past, what were the retreat rates, and were those associated with climate warming, said Briner. Preliminary conclusions are that the Jakobshavn Isbrae is tightly linked to climate change. The glacier’s fastest retreat rates occurred in the middle Holocene, at the height of the warmest temperatures. Then, when the Little Ice Age occurred, there was a rapid response and glacial growth—the glacier advanced about 35 kilometers—followed by significant retreat of 30 kilometers since the modern, 20th century warming began, said Briner.

“This tells us that when there is a climate perturbation, Jakobshavn has a really monstrous response,” he said.

Improving Climate Change Models

This information could help improve the accuracy of climate models. Currently the Intergovernmental Panel on Climate Change (IPCC) is hampered by a lack of models that can accurately predict complex ice flow. By incorporating long-term, historic data and reconstructed climates, modelers will have a critical baseline by which to measure what the ice sheet did then and simulate potential actions it may take now, Briner said.

And though this specific research project on the Jakobshavn was only a two-year pilot study on the feasibility, Briner is confident much more research remains.

“Our initial project is limited in scope and we’ve had great success in doing what we said we were going to,” Briner said. “The possibilities for what’s next are big.”

In fact, one of Jason Briner’s next projects is huge: he leads the U Buffalo component of a 10-institute collaborative funded by NSF and led by Darrell Kaufman (U Northern Arizona). The investigators will collect lake sediments all over the Arctic for very detailed climate history information going back about 8000 years.  Read our recent conversation with Darrell Kaufman here.

At Work in Lake Country

A conversation with Darrell Kaufman

Allison Lake, near Valdez, Alaska. All photos by Darrell Kaufman.

Darrell Kaufman readily admits he has been “hooked on the wildness of Alaska since my first visit in 1979.” Peek at the photo gallery on his Web site and you can understand why. Scores of images show the professor of geology and environmental science (Northern Arizona University) and his students in gorgeous Alaskan wilderness, camping, hiking, boating—in fact, working.

Kaufman has a long career of field research in Alaska. “After I graduated from college in 1982, I lived in Anchorage for three years,” he explained in a recent email, “and I worked two-month-long field seasons with the USGS on a large-scale mapping project across the Seward Peninsula.

“The hook was set firmly then, and I knew that I wanted to keep exploring the Alaskan wilderness, and to keep living the long days of the arctic summer. I’ve been exceptionally fortunate to have been supported for field work in Alaska continuously for the last 25 years. Each year, I find myself in new and remarkable landscapes, or I revisit lakes were my group has been monitoring for years to find it in an entirely new light. It’s the brief moments between the rain and the bugs, and after the back-breaking work and contingency planning are finished, when I can stop to look around and take in the exceptional beauty and to consider my great fortune to work in places where many others only dream of visiting. To be certain, field work in Alaska is non-stop hard work, but it’s good work with a purpose, and bringing new students to the field each year refreshes me and the whole experience.”

"Living the long days of the arctic summer." The Kaufman camp at Cascade Lake, 2007.

Kaufman and colleagues recently published results of a four-year National Science Foundation-funded study in the journal, Science, which summarized their collaborative work on arctic lake sediments. Kaufman, who studies lake sediments for clues about arctic climate, will begin another large project  funded by the NSF next season by coring sediments from lakes across southern Alaska, from the Aleutian Islands to the Chugach Mountains.

We recently asked him about his work.

Caleb Schiff with a surface core, Andrew Lake, near Adak.

What is the importance of North American lakes in understanding climate change?

Lakes are widely distributed across the Arctic and they contain a variety of evidence about past environmental and climate changes.

What information do lake sediments preserve?

For example, the primary producers in Arctic lakes are diatoms [microscopic algae], and the lake sediment preserves the remains of the diatoms that grow each year.  We can relate the abundance of diatom remains to the warmth of the summer. Warmer summers are associated with longer open-water periods, which allow more diatoms to bloom. Changes in the abundance of diatoms that grew over the last 50 or 100 years and are preserved in the sediment at the lake bottom can be compared with temperatures from nearby weather stations. We can then apply this calibration down the sediment core to infer the changes in temperature that took place prior to thermometer-based records.

How much time do Arctic lake sediments typically preserve?

Most of the deeper lakes occupy basins scoured out during the last ice age, about 15,000 years ago. Some places in the Arctic were not covered by glacier ice and the deepest lakes contain sediment that extends even further back in time.

Why is understanding the behavior of the Aleutian Low important to understanding climate change?

It’s a major feature of ocean-atmospheric circulation in the North Pacific region. We’d like to understand how it behaved over centuries or millennia as ocean-atmospheric circulation was forced to change as climate itself changed.

Why is the medieval warm period important to your studies?

Studying periods when temperatures were relatively warm can provide clues as to how the Arctic system behaves under warmer conditions. It now appears that the last few decades were warmer than anytime during at least the last 2000 years, including the medieval period.

Will you talk a little about how you plan to compare and contrast records from glacially fed versus organic lakes?

No two lakes are the same. Each one reflects the unique conditions of its watershed and limnology. Lakes that are fed by glaciers are turbid and inorganic; lowland lakes in vegetated landscapes receive less sediment and more nutrients to support abundant aquatic life.

Sediment in glacier-fed lakes can often be interpreted in terms of changes in the melting of glaciers that feed the lake, which in turn reflect changes in winter precipitation and summer temperature. In contrast, the sediment in organic-rich lakes can often be interpreted in terms of environmental changes that control biological productivity, which in turn reflect temperature and other climate factors. By combining evidence from multiple lakes, we can develop a richer picture of past environmental and climate changes.

Heidi Roop and PolarTREC teacher Barney Peterson examine a sediment trap, Cascade Lake, Ahklun Mountains.

How do you choose which lakes you will study?

Accessibility, location, and suitability for a particular proxy type, among other factors. We typically core lakes in the summer when we can also survey the bathymetry and sample inflow streams, so the lakes need to be large enough to land a float plane. To capture the footprint of the Aleutian low-pressure system, our transect of study lakes extends from the central Aleutian islands in the west to the easternmost Chugach Range.

How many lakes did you sample last summer and where are they?

We recovered exploratory cores from three lakes on Adak Island, and a suite of new cores from lakes in the Bristol Bay area, and near Valdez. We also returned to our sediment and weather monitoring stations at three other lakes in the Ahklun Mountains.

Will you summarize this summer’s logistics?

We charter our most-trusted pilots and their float planes to fly us and our coring gear to the lakes, then we set up camp by the lake and use inflatable boats and platforms to take the sediment cores. It takes four or five people to do the hard work coring sediment. This summer, we also hosted a PolarTREC teacher, who was a great help.

What is a ‘typical day in the field’ for your group?

Early rise; work all day; collapse in the sleeping bag — repeat.

Removing water from the surface of a sediment sample.

Please briefly explain your methodology for acquiring lake sediment samples.

We lower core tubes three to six meters long to the lake bottom — sometimes 50 meters deep — on a cable from a floating platform, and use a hammer on a rope to tap the tube into the mud, inch by inch. Then we hoist the tube from the lake bottom and hope that the mud stays in. It’s a good day when we get tubes filled with mud.

Coring Allison Lake.

How do you get your samples out of the field?

We split the core tubes lengthwise and hope for dry weather so that any soupy mud dries slightly — enough to stabilize. We then wrap each half with bundling film, which holds the mud tightly within the core tubes. The tubes are then shipped to our lab at Northern Arizona University where they are kept in cold storage and sampled for a variety of analyses.

How do you process your samples back in the lab?

The cores are analyzed for a variety of biological and physical properties. We typically sample the upper 100 years of sediment in two-milimeter-thick intervals to generate a detailed record to compare with historical records of climate from nearby meteorological stations. The rest of the core is typically sampled at one-centimeter intervals to analyze for the abundance of organic matter, including diatoms and pollen. Samples are distributed to collaborators who work on all types of biological materials that are well preserved in the lake sediment. Every lake that we have cored in Alaska contains multiple layers of volcanic ashes, and we are collaborating with the Alaska Volcano Observatory on studying these deposits.  For glacier-fed lakes, it’s the sedimentary layers themselves that are the focus of our analyses. Determining the age of the sediment down the core is critical, and we spend a lot of time isolating bits of vegetation for radiocarbon dating. Without good age control, it’s difficult to relate the changes in the sediment to changes that are known from elsewhere.

Surface core from Lake Leon, near Adak.

What do you hope to learn from this study?

We want to learn more about how the ocean-atmospheric circulation of the North Pacific region responds to climate change.

How do you expect your southern Alaska results will contribute to your upcoming study?

Our results from lakes in southern Alaska will be integrated into a larger network of proxy climate records from around the Arctic. In particular, the results will help us to understand how the Arctic and North Pacific climate systems interact.

What is the most challenging thing about working in the Arctic region?

Accessing the field sites takes a lot of planning and a lot of time to just get there. We probably spend ten days either preparing or waiting out the weather for each day we have on task in the field. The weather is a huge factor in determining the success of our field work. We can’t work on lakes when the wind blows.

What is the most important thing you’d like for people to know about your work?

Lakes provide an ideal focus for multi-disciplinary research, and the Arctic/Subarctic has loads of lakes, most of which have not yet been severely altered by human activities. Understanding how to interpret past climate changes from the biological and physical properties of lake sediment is not easy, but when a team of scientists work to fit the pieces together, it can be extremely rewarding.

In The News

Why is this Woman Smiling?

Grad student Heidi Roop (Northern Arizona) in the port of Darrell Kaufman's lake sediment coring rig. Photo from Kaufman's 2007 gallery

Congratulations to the team of scientists led by Darrell Kaufman (Northern Arizona University) on their recent article in the journal Science.  The piece (available to subscribers and summarized here) reports that a 2000-year-long cooling trend in the Arctic had been reversed in the 20th century, with four of the five warmest decades in 2000 years occurring between 1950 and 2000. The news made headlines in major publications and blogs.  The project was funded by the National Science Foundation, and CPS has happily supported Kaufman team visits to lakes around  Alaska for lake sediment cores, proxy for paleoclimate information, for years.

This is why you should do your science homework: a Kaufman research camp at Upper Togiak Lake, Alaska, in 2007. Photo from Kaufman gallery

NOAA announced plans to sample air in Alaska to determine the natural sources of methane and carbon dioxide—the two most important heat-trapping gases—using a Coast Guard C-130 aircraft. The effort aims to identify the concentrations and sources of major green house gas emissions and make plans for reducing them to stave off global warming.

Warming temperatures are causing rapid ice melting in the Arctic. Photo courtesy noaa.gov, which issues an annual Arctic climate report card.

“Them killer whales, first time people seen them here in the harbor,” says Eddie Gruben, 89, of tiny Tuktoyaktuk, NW Territories, Canada. Read about the challenges facing “Tuk” and myriad other polar communities facing a warming Arctic in this Los Angeles Times article.

Climate warming may have adverse effects on Arctic plants. Photo courtesy British Broadcasting Corporation.

Watch Alaska’s mighty Mendenhall Glacier retreat over the better part of a year, thanks to time-lapse photography by the Extreme Ice Survey folks:

EIS_350 from Extreme Ice Survey on Vimeo.