After drilling through the ice at the North Greenland Eemian Ice Drilling Project (NEEM), an international team of scientists this week hit bedrock 1.5 miles beneath the ice surface. In doing so they recovered ice from the Eemian interglacial period—between 115,000 to 130,000 years ago. During that time, atmospheric temperatures were warmer than they are today, said Jim White, director of the Boulder, CO-based Institute of Arctic and Alpine Research.
The Past as Analogue for the Future
“The Eemian, or the last interglacial period, is the last time climate was as warm as it is today," White said in a radio interview on Aug. 3 with KGNU. "In fact, it was warmer than it is today. And that’s important because as climate warms, we want to know what the impacts are going to be. How much ice is going to melt, how are the climate patterns going to change, are the agricultural areas going to stay the same or are they going to change. And the last interglacial period, being warmer, is a good analogue for the future.”
Higher Sea Levels
During the Eemian, sea levels were more than 15 feet higher than they are today. Scientists predict that melting sea ice could cause sea levels to rise more than three feet by the end of this century.
Studying ice cores from the Eemian period could unlock climate mysteries because the new cores are thicker and more intact than previous ice cores drilled in Greenland in the last 20 years. In the earlier cores, the deepest layers were compressed and folded, making the data difficult to interpret.
Annual ice layers formed over millennia in Greenland by compressed snow reveal information on past temperatures and precipitation levels, as well as the contents of ancient atmospheres, said White. Ice cores from previous drilling efforts revealed temperature spikes of more than 20 degrees Fahrenheit in just 50 years in the Northern Hemisphere.
Ice Cores and Climate
White said the latest cores would offer critical insight for forecasting future weather and climate.
"The cores tell us that these interglacial periods, and climate in general, is not a static thing," he said in his radio interview. "We should expect change. We should expect that sea level will change. We should expect that temperatures will change. We should not be surprised that climate changes when we do something as fundamental as adding greenhouse gases to the atmosphere.”
An international study released by the National Oceanic and Atmospheric Administration last week showed the first decade of the 21st century was the warmest on record for the planet.
An International Affair
The NEEM project involves 300 scientists and students and is led by Professor Dorthe Dahl-Jensen, director of the University of Copenhagen's Centre of Ice and Climate. The United States portion of the effort is funded by the National Science Foundation's Office of Polar Programs.
A View Into the Past
The two meters of ice just above bedrock from NEEM -- which is located at one of the most inaccessible parts of the Greenland ice sheet -- go beyond the Eemian interglacial period into the previous ice age. It contains rocks and other material that have not seen sunlight for hundreds of thousands of years, said White. The researchers expect the cores to be rich in DNA and pollen that can tell scientists about the plants that existed in Greenland before it was covered with ice.
The core samples are being studied in detail using a suite of measurements, including stable water isotopes that reveal information about temperature and moisture changes back in time. The team is using state-of-the art laser instruments to measure the isotopes, as well as atmospheric gas bubbles trapped in the ice and ice crystals to understand past variations in climate on a year-by-year basis, said White.
Greenland—Before the Ice
As part of the project, the researchers want to determine how much smaller the Greenland ice sheet was 120,000 years ago when the temperatures were higher than present, as well as how much and how fast the Greenland ice sheet contributed to sea level.
The NEEM facility includes a large dome, a drilling rig to extract 3-inch-in-diameter ice cores, drilling trenches, labs and living quarters. The United States is leading the laboratory analysis of atmospheric gases trapped in bubbles within the cores, including greenhouse gases like carbon dioxide and methane.
Other nations involved in NEEM include Belgium, Canada, France, Germany, Iceland, Japan, Korea, the Netherlands, Sweden, Switzerland and the United Kingdom. Other U.S. institutions involved in the effort include Oregon State University, Penn State, the University of California, San Diego and Dartmouth College. —Rachel Walker