Changing Planet

120,000-year-old Ice Yields Clues to Climate of a Warmer Earth

More than a mile of ice core was pulled from the Greenland ice sheet by scientists this summer, setting a new record for single-season deep ice-core drilling.

The researchers, from 14 countries and led by the University of Copenhagen, are on a quest to recover ice formed 120,000 years ago, the last time our planet was in a period of warm climate such as the one many scientists think we are now entering.


Pushing an ice core out of the drill.

Photo courtesy NEEM ice core drilling project

“Evidence from ancient ice cores tell us that when greenhouse gases increase in the atmosphere, the climate warms,” says University of Colorado at Boulder Professor Jim White, who is leading the U.S. research contingent. “And when the climate warms, ice sheets melt and sea levels rise.

“If we see comparable rises in sea level in the future like we have seen in the ice-core record, we can pretty much say good-bye to American coastal cities like Miami, Houston, Norfolk, New Orleans and Oakland.”

“If we see comparable rises in sea level in the future like we have seen in the ice-core record, we can pretty much say good-bye to American coastal cities like Miami, Houston, Norfolk, New Orleans and Oakland.”

This year’s drilling operation reached a depth of 1,758 meters (5,767 feet) in early August, where ice layers date to 38,500 years ago during cold glacial period preceding the present interglacial, or warm period.

“The team hopes to hit bedrock at 2,545 meters (8,350 feet) at the end of next summer, reaching ice deposited during warm Eemian period that lasted from roughly 130,000 to 120,000 years ago before the planet began to cool and ice up once again,” says a statement about the project released by the National Science Foundation yesterday.

The goal of the North Greenland Eemian Ice Drilling (NEEM) project is to retrieve ice from the the Eemian Period.

Annual ice layers formed over millennia in Greenland by compressed snow reveal information on past temperatures and precipitation levels and the contents of ancient atmospheres, said White, who directs CU-Boulder’s Institute of Arctic and Alpine Research. “Ice cores exhumed during previous drilling efforts have revealed abrupt temperature spikes of more than 20 degrees Fahrenheit in just 50 years in the Northern Hemisphere.”

The period was warmer than today, with less ice in Greenland. That led to 15-foot (5-meter) higher sea levels than present–conditions similar to those Earth faces as it warms in the coming century and beyond, White says.


This MODIS Terra image, acquired August 23, 2006, shows the southern portion of Greenland. The Greenlandic ice cap covers about 80 percent of the island’s surface. Photo courtesy NASA

While three previous Greenland ice cores drilled in the past 20 years covered the last ice age and the period of warming to the present, the deeper ice layers representing the warm Eemian, and the period of transition to the ice age were compressed and folded, making them difficult to interpret, he says.

“Radar measurements through the ice sheet from above the NEEM site have indicated the Eemian ice layers below are thicker, more intact and likely contain more accurate, specific information.

“Every time we drill a new ice core, we learn a lot more about how Earth’s climate functions,” White said. “The Eemian period is the best analog we have for future warming on Earth.”

Increased warming on Earth has a host of potentially deleterious effects, including changes in ecosystems, wildlife extinctions, the growing spread of disease, potentially catastrophic heat waves and increases in severe weather events, according to scientists.

While ice cores pinpoint abrupt climate change events as Earth has passed in and out of glacial periods, the warming trend during the present interglacial period is caused primarily by human activities like fossil fuel burning, White says.

“What makes this warming trend fundamentally different from past warming events is that this one is driven by human activity and involves human responsibility, morals and ethics.”

The NEEM project is led by the University of Copenhagen’s Centre of Ice and Climate directed by Professor Dorthe Dahl-Jensen. The U.S. and Denmark are the two leading partners in this project. The U.S. effort is funded by the National Science Foundation’s Office of Polar Programs.

The project began in 2008 with the construction of a state of the art facility, including a large dome, the drilling rig for extracting three-inch in-diameter ice cores, drilling trenches, laboratories and living quarters. The official drilling started in June 2009.

The United States is leading the laboratory analysis of atmospheric gases trapped in bubbles within the NEEM ice cores, including greenhouse gases like carbon dioxide and methane.

Other nations involved in the project include the United States Belgium, Canada, China, France, Germany, Iceland, Japan, Korea, the Netherlands, Sweden, Switzerland and the United Kingdom.

Forty years in U.S., UK, and South African media gives David Braun global perspective and experience across multiple storytelling platforms. His coverage of science, nature, politics, and technology has been published/broadcast by the BBC, CNN, NPR, AP, UPI, National Geographic, TechWeb, De Telegraaf, Travel World, and Argus South African Newspapers. He has published two books and won several journalism awards. He has 120,000 followers on social media. David Braun edits the National Geographic Society blog, hosting a global discussion on issues resonating with the Society's mission and initiatives. He also directs the Society side of the Fulbright-National Geographic Digital Storytelling Fellowship, awarded to Americans seeking the opportunity to spend nine months abroad, engaging local communities and sharing stories from the field with a global audience. Follow David on Facebook  Twitter  LinkedIn
  • Half Tide Rock

    Greetings, I wish to register an objection to the assertion that this global warming period is anthropogenic in nature. A simple assertion does not a proof make.
    The basis for my objection is the well known data from the Vostoc Ice Cores.
    The data shows four symetrical periods of global warming in the past 450,000 years and that this particular warming period started approximately 16,000 years ago.
    The data shows a correlating increase in Methane and CO2 in periods of low human activity which put to rest the assertion that this climate chance regieme is anthropogenic in origin.
    In addition the infra red absorbtion spectrum of CO2 was fully absorbed at 100 PPM. Additional CO2 effect is an inverse square relationship.
    It is a sad day when science is hijacked. It has happened before and it will happen in the future. The hijack normally ends with a rapid paradigm shift.
    The perma frost record in North America goes back at least 750,000 years and some of the ice in Antartica may be 8 million years old.
    I understand that human self flagilation is in vogue. Do not convieniently mix correlation up with causeation.
    The climate is cyclical, there are ramifications we are blessed to be unraveling the mysteries of this planet. It does not help the investigations by going down political dead ends.
    I cite Galeleo’s death still under house arrest.

  • Nastya

    I agree with Half Tide Rock. The planet’s climate does get warmer and cooler on a cyclical basis. However, the hypothesis of human-caused climate change is unfounded.
    The natural influences on the global environment, like our variable sun and the Earth’s axial tilt among others, are so great that it is very unlikely that human technology will ever be able to affect Earth’s climate.
    Peace and Reason

  • datadriven

    Half Tide Rock and Nastya- I’m not sure anyone here is talking about the causes of global warming periods. Your straw man argument is out of place when there is so much more to learn before we can assert “Knowledge” of such a vast subject as earth and climate.
    I do think this article (and the excellent tv program that brought me here) shows that some people are getting very good information about the earth’s history, including the relationship of high CO2 levels and periods of climate warming.
    I’m grateful to these scientists and their careful coring and recording activities. The info they collect is being shared all around the world. Scientists will be looking at the data with open minds – we should be so wise.

  • MillerJamesD

    According to this scientist, we’ve been at much higher CO2 % levels and temperatures in earth history. What do you peers think of his article and graphs at:
    Thanks, Jim

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