July 16, 2008
The core, which is longer than 1 and 1/2 football fields football fields, is the longest extracted from an arctic glacier in the United States, according to Matt Nolan, an associate professor at the University of Alaska Fairbanks Institute of Northern Engineering who has led research at McCall Glacier for the past six years. The sample spans the entire depth of the glacier and may cover 200 years of history, he said.
"What we hope is that the climate record will extend back into the Little Ice Age," said Nolan. "Up until the late 1800s these glaciers were actually growing."
UAF photo by Matt Nolan
Ice core samples offer a window into past climate using clues, such as gas bubbles or isotopes of oxygen and hydrogen, locked in the ice when it formed. In addition, debris in the ice, such as layers of volcanic ash and pieces of organic material such as insects, can help scientists draw a timeline through the depth of the glacier.
Because McCall Glacier has been studied extensively since the International Geophysical Year in1957-58, the research history there offers a unique opportunity to compare ice core data with a wealth of related information, such as ice temperature and speed, air temperature and snowfall, and models of how the glacier changes within those parameters. Those comparisons with the modern parts of the ice core can help scientists better understand changes in the older sections, Nolan said.
"Due to its remote location, long-term instrumental climate data here are sparse to nonexistent, so ice cores from this glacier are one of our few means to determine climate variations in this huge region over the past few hundred years," Nolan said. "We are also quite fortunate and privileged to be granted permission for this work. Research at McCall Glacier predates the formation of the refuge and meshes well with scientific aspects of the refuge's mission to conduct long-term ecological research."
UAF photo by Matt Nolan
"The drill team did an excellent job of making their tools work in challenging conditions, in particular drilling the last 80 meters of core under water," Nolan said. "This is a very unusual situation for ice coring, as most cores are taken from summits of cold, dry polar ice sheets not warm, flowing valley glaciers."
At 150 meters, drillers hit a rock at what the team believes was the bottom of the glacier, based on radar measurements of ice depth.
The ice cores were flown to Fairbanks and are being housed at the Alaska Ice Art Museum until the fall, when glaciologists will return from the field to begin analysis.
The McCall Glacier project is part of UAF's contribution to research efforts during the fourth International Polar Year. Nolan's research at McCall Glacier is funded by the National Science Foundation and is part of a cooperative effort, involving 15 other nations, to gain a better understanding of the dynamic response of arctic glaciers to recent climate change. IPY is an international endeavor that is focusing research efforts and public attention on the Earth's polar regions. Other partners on the field team included the University of Silesia in Poland and the Kitami Institute of Technology in Japan. Additional core analysis will be performed at Ohio State University and the Free University of Brussels in Belgium.
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