From the Field

Kristin Schild, Ph.D. Student

Earth Sciences

Kristin is studying specific environmental controls, such as warming temperatures that are driving an increase in ice mass loss through Greenland’s tidewater glaciers. She uses remote sensing (satellite imagery and time lapse cameras taking pictures of the glacier terminus) to determine how much of the glacier is experiencing melt and when meltwater exits the glacier and enters the fjord. The timing between melt onset and when the meltwater emerges gives her an idea as to how the meltwater travels through and below the glacier.

Kristin and her colleagues have found that the fastest flowing glaciers episodically release meltwater rather than con¬stantly discharging water through efficient subglacial networks. A buildup of water beneath the glacier creates pressure and causes these glaciers to move faster.

Chris Polashenski, Ph.D.

Engineering Sciences

Chris studies the Greenland Ice Sheet (GIS), which is the second largest ice cap in the world and contains 10% of Earth’s glacial ice. In the past several years, melt on the GIS has been increasing and contributing to sea level rise, but understanding how rapidly the ice sheet will melt in the future remains fairly limited.

Chris has executed two long traverses on the GIS to determine what controls the amount of sunlight absorption, and thus melt, on the surface of the ice. In 2012, a number of major wildfires in the Northern Hemisphere during late spring and early summer resulted in large depositions of black carbon onto the GIS, darkening the ice in a way that may have increased sunlight absorption and thus the amount of melt.

Chelsea Vario Petrenko, Ph.D. Student

Ecology and Evolutionary Biology

Arctic soils contain more than half of the soil carbon that is stored worldwide. Because microorganisms are more active at higher temperatures, warming temperatures in the Arctic could cause a significant release of carbon from soils to the atmosphere, creating a positive feedback to climate change.

Chelsea is measuring the sensitivity of Greenlandic soils to warming temperatures and determining if and how vegetative cover (shrub versus grass-dominated) influences belowground soil carbon dynamics.

During the summer of 2012, Chelsea and her colleagues collected 20 deep soil cores from two locations near Kangerlussuaq, Greenland, a near-ice zone and a zone further away from the ice sheet. They are measuring soil texture, pH, carbon and nitrogen content, and doing sequential carbon extractions.

Thomas Overly, Ph.D. Student

Earth Sciences

Combining a background in remote-sensing, glaciology, and cultural geography, Thomas examines how people can integrate knowledge to best understand and prepare for polar environmental change.

Thomas is interested in the future of the Greenland Ice Sheet by understanding rates of snow accumulation and loss to determine rates of mass balance change through time. He uses methods from satellite remote sensing and the direct measurement of snow accumulation on the ice sheet made during ground traverse expeditions from the northwest coast of Greenland to Summit Station in the deep interior.

Laura Levy, Ph.D.

Earth Sciences

The future of the Greenland Ice Sheet is uncertain due to modern day climate change. Laura looks at how the Greenland Ice Sheet and glaciers in Greenland have responded to climate changes during the past 11,500 years in order to help understand how it will change in the future. She uses detailed mapping and surface exposure dating of glacier deposits and analyses of glacial lake sediments.

Laura’s research shows that the western margin of the Greenland Ice Sheet, near Kangerlussuaq, was behind its present limit from 6,500 years ago to the mid-19th century. She has also developed a climate record along the margin of the ice sheet near Scoresby Sund, in eastern Greenland, which shows that over the last 10,000 years, glaciers responded to long-term (for example, changes in the intensity of incoming solar radiation) and also to short-term climate changes that have occurred over the past few thousand years.

Benjamin Kopec, Ph.D. Student

Earth Sciences

Ben studies the current state of the hydrologic cycle across Greenland and surrounding regions and how it might change with a warming climate. In 2011 and 2012, Ben traveled to Kangerlussuaq, Greenland, to measure water chemistry in lakes and water vapor concentrations in the air.

Together with his colleagues, they ultimately found that many of the lakes are declining in size as a result of very high evaporation rates and low precipitation. He also found that a strong interaction in the coastal regions between glacial air masses over the ice sheet and marine air masses is an important feature of the local climate.

Ice Core Research Is History Lesson

Engineering Sciences

Kaitlin Keegan, PhD, studies firn, the top 100 meters of an ice sheet that contains snow layers that are compacting are undergoing the process of becoming glacial ice. Firn is where climate information gets recorded into the ice sheet. If we understand how climate information gets recorded then we can understand how climate has changed naturally in the past.

In 2009, Kaitlin and colleagues drilled an 80-meter deep core of firn layers at NEEM camp, in Northern Greenland. The core was shipped to a lab in the U.S. where they’ve studied the various layers and their properties. One significant finding was a layer in the firn that formed in 1889 and indicated a widespread melt event over the entire surface of the Greenland Ice Sheet.

Soils Biologist Studies Past and Present Erosion in South Greenland

Ruth Heindel, Ph.D. Student, Earth Sciences

Ruth Heindel studies soils, a valuable resource for Greenland that supports natural ecosystems and also agricultural activity in South Greenland. Specifically, she studies past and present wind-driven soil erosion, a process that threatens soil resources by removing soil and disturbing vegetation.

During the summers of 2012 and 2013, Ruth collected spatial data describing eroded areas in the Kangerlussuaq region. Additionally, she measured lichen diameters in order to estimate past and present rates of soil erosion. In the spatial analysis lab at Dartmouth, Ruth has developed a land cover classification for the Kangerlussuaq region that identifies eroded areas from satellite imagery. She has found that eroded areas generally occur on steep south-facing slopes, and are much more common closer to the Greenland Ice Sheet.

Alexandra Giese, Ph.D. Student

Earth Sciences

Alexandra's glaciology research has focused on understanding properties of Greenland's snow, the historical stability of the West Antarctic ice sheet, and, currently, the amount of melt from the largely enigmatic debris-covered glaciers in the Nepalese Himalayas. 

The steep sides of Himalayan mountains deposit substantial rock covers on the glaciers in their valleys. While these debris-covered glaciers are generally shrinking in response to a warming climate, the mechanisms, patterns, and timescales of their melt differ from those of their better-understood clean counterparts.  

Zak Gezon, Ph.D. Student

Ecology and Evolutionary Biology

As the climate changes, spring is arriving earlier and earlier across the globe. The migration of birds, mating of amphibians, and emergence of insects and flowers is happening earlier than it historically has due to the warming climate and early arrival of spring.  The timing of these natural history events (known as “phenology”) can have dramatic consequences for species reproduction and survival.

For example, when flowering plants bloom too early, the probability of experiencing frost damage and drought increases. Furthermore, approximately 90% of flowering plants require pollination by bees or other organisms for reproduction, but the phenology of bees might not respond to climate change at the same rate as flowering phenology. Therefore, plants and bees could emerge at different times, and experience a “phenological mismatch,” which is hypothesized to have negative consequences for both plants and bees. Although we know that plant reproduction tends to decrease when plants bloom too early, we do not know why, specifically. 

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