Research on McCall Glacier

McCall Glacier is a small glacier on the north side of the Brooks Range in Alaska, located in the Arctic National Wildlife Refuge (ANWR). It is has the longest history of scientific observation of any Arctic glacier in the U.S., dating back to the late 1950s. Perhaps the most valuable observations are the long-term record of mass balance, which relates to climate variations over the past century.

The last published mass balance measurements date to the mid-1990s. From this record, it is clear that the rate of ice loss from McCall Glacier has substantially increased since the 1970s. An important component of our research is to extend this record until 2008. Through collaborations with other research groups, we hope to extend the climate record into the past through a combination of ice coring and glacial geology.

Our first field trip for this research took place in May 2003 and was a great success. We installed two weather stations, which we hope to connect directly to the internet in fall. We installed over 70 survey poles, that will yield information on mass balance and ice velocity. We reoccupied about 200 locations on the glacier surface at which prior elevations measurements had been, giving us the means to measure volume change since the last study in 1993. We installed a thermistor string to 13 m depth at the same location as had been measured in 1972 and 1993. And we measured surface elevations of 5 other glaciers nearby.

This project is one component of a larger NSF project to study freshwater inputs to the Arctic Ocean. The Arctic Ocean is a relatively small ocean that drains several large continents, thus it receives the highest proportion of freshwater to surface area of any ocean. This freshwater has a different density than saltwater, and mixes with the surface water to make a relatively fresh upper layer. Because much of the water leaving the Arctic Ocean drains through Fram Strait between Greenland and Svalbard as well as the channels of the Canadian Archipelago between Greenland and North America, this freshwater input has the potential to limit or stop the North Atlantic Deep Water formation because it is so fresh, and light, that mixing is difficult despite the cooling that normally occurs. This circulation brings warm equatorial water north past Europe, keeping Europe about 8C warmer than it would be otherwise. Glaciers today are generally receding from an advanced stage which was caused by a cooling that began about 500 years ago, thought to be due to a disruption in this ocean circulation, caused possibly by the variation in freshwater export from the Arctic Ocean. Our project therefore seeks to identify changes to arctic lakes, rivers, aufeis, soil moisture and glaciers over the past 50-100 years, determine the causes of those changes, and shed light on how these changes will affect climate in the future.

The McCall Glacier project has several goals related to this overall project. First, we seek to understand the long-term trends in our mass balance observations. What is the primary driver of the annual variations: precipitation, wind direction, air temperature, cloudiness? Second, we want to extend this record to the unrecorded past and to a broader area to determine how glacier meltwater inputs into the Arctic Ocean have varied over the past 100-200 years (since the end of the Little Ice Age). Third, we would like to predict how much meltwater will be added in the future so that oceanographers may better predict how this may affect North Atlantic circulation. There are also many interesting glaciologic phenomena occuring on McCall Glacier. Prior research has identified an region which may be sliding along its bed, which is unusual for an Arctic glacier. We have therefore installed several cross-sectional and longitudinal transects of poles and a continuously recording GPS to capture the dynamics there. McCall Glacier also has an unusually shaped equilibrium line, which often runs longitudinally. Our observations in 2003 suggest that wind erosion may play an important role in this, and our weather stations and continuously recording snow depth measurements will hopefully shed light on this, as may a web cam not yet installed.

You can view a neat visualization of the McCall Glacier area here, if you have TerraExplorer installed. Nothing is labelled yet, but I hope to add those soon. You can download a map of our stake network here. Below are some photos from our May trip.

The spring expedition team: Andy, Kristin, Bernhard, Bjorn and Matt, on Mt Ahab installing a weather station.

The installed weather station, with Okpilak river valley in the distance.

Using RTK D-GPS to locate prior measurement sites and place new poles.

Steam drilling holes for poles in a blizzard.

Drilling on a nicer day.

Dropping a 6 meter pole into place.

Recording snow stratigraphy.

Slogging uphill back to camp.

Our home away from home.

Midnight snacks.