Banner
    Greenland Ice Core Shows Ice Age Temperatures Rose 22 Degrees In 50 Years
    By News Staff | June 19th 2008 07:00 AM | 3 comments | Print | E-mail | Track Comments
    Information gleaned from a Greenland ice core by an international science team shows that two huge Northern Hemisphere temperature spikes prior to the close of the last ice age some 11,500 years ago were tied to fundamental shifts in atmospheric circulation.

    The ice core showed the Northern Hemisphere briefly emerged from the last ice age some 14,700 years ago with a 22-degree-Fahrenheit spike in just 50 years, then plunged back into icy conditions before abruptly warming again about 11,700 years ago. Startlingly, the Greenland ice core evidence showed that a massive "reorganization" of atmospheric circulation in the Northern Hemisphere coincided with each temperature spurt, with each reorganization taking just one or two years, said the study authors.

    The new findings are expected to help scientists improve existing computer models for predicting future climate change as increasing anthropogenic greenhouse gases in the atmosphere drive up Earth's temperatures globally.

    The team used changes in dust levels and stable water isotopes in the annual ice layers of the two-mile-long Greenland ice core, which was hauled from the massive ice sheet between 1998 to 2004, to chart past temperature and precipitation swings. Their paper was published in the June 19 issue of Science Express, the online version of Science.

    The ice cores -- analyzed with powerful microscopes -- were drilled as part of the North Greenland Ice Core Project led by project leader Dorthe Dahl-Jensen of the Centre for Ice and Climate at the Neils Bohr Institute of the University of Copenhagen. The study included 17 co-investigators from Europe, one from Japan and two from the United States -- Jim White and Trevor Popp from the University of Colorado at Boulder.

    "We have analyzed the transition from the last glacial period until our present warm interglacial period, and the climate shifts are happening suddenly, as if someone had pushed a button," said Dahl-Jenson.

    According to the researchers, the first abrupt warming period beginning at 14,700 years ago lasted until about 12,900 years ago, when deep-freeze conditions returned for about 1,200 years before the onset of the second sharp warming event. The two events indicate a speed in the natural climate change process never before seen in ice cores, said White, director of CU-Boulder's Institute for Arctic and Alpine Research.

    "We are beginning to tease apart the sequence of abrupt climate change," said White, whose work was funded by the National Science Foundation's Office of Polar Programs. "Since such rapid climate change would challenge even the most modern societies to successfully adapt, knowing how these massive events start and evolve is one of the most pressing climate questions we need to answer."

    Both dramatic warming events were preceded by decreasing Greenland dust deposition, indicating higher tropical temperatures and significantly more rain falling on the deserts of Asia at the time, said White. The team believes the ancient tropical warming caused large, rapid atmospheric changes at the equator, the intensification of the Pacific monsoon, sea-ice loss in the north Atlantic Ocean and more atmospheric heat and moisture over Greenland and much of the rest of the Northern Hemisphere.

    "Here we propose a series of events beginning in the lower latitudes and leading to changes in the ocean and atmosphere that reveal for the first time the anatomy of abrupt climate change," the authors wrote. White likened the abrupt shift in the Northern Hemisphere circulation pattern to shifts in the North American jet stream as it steers storms around the continent.

    "We know such events are in Earth's future, but we don't know when," said White. "One question is whether we can see the symptoms before big problems occur. Until we answer these questions, we are speeding blindly down a narrow road, hoping there are no curves ahead."

    Each yearly record of ice can reveal past temperatures and precipitation levels, the content of ancient atmospheres and even evidence for the timing and magnitude of distant storms, fires and volcanic eruptions, said White. The cores from the site -- located roughly in the middle of Greenland at an elevation of about 9,850 feet -- are four-inch-diameter cylinders brought to the surface in 11.5-foot lengths, said White.

    Comments

    Aupak
    I am betting that humans are to blame for that 50 ago study, for missing something that might have happened and ruling it out. Also, we are extracting oil and this changes the atmospheric temperatures to reflect how much oil we have depleted so far. I think I can link "Global Warming" to "Oil Extraction". With this information, and common sense, who wouldn't? I mean, this "Greenhouse Gas Emissions", people think that it is reflecting back the warmer temperatures, I mean, come on, we will need to emit more carbon dioxide to have this noticeable change in the temperature. In conclusion, the extraction of oil is more adequate, with the extreme heat coming from under the earth and not from the sun. And I also think that so far, since we began to emit smoke up to the atmosphere, I think it has just helped us to keep cool! Also, you can probably trace the atmospheric change to asteroids that might have missed earth when Hudson Bay was first created, whenever that might be.
    If the earth can naturally heat up that fast, why is it so hard to be at least skeptical about the minimal warming Global Warming advocates propose is occurring now?

    And what if Global Warming IS natural? What are we going to do about it if its going to happen despite our loyal contributions to Al Gore's finances and the bankers of Wall Street? Something tells me Carbon Taxes don't keep water out from flooding cities!

    How about we focus on cleaning up things as best we can, creating a smarter, technologically advanced, and healthier society, and be prepared to face any environmental challenge that comes our way, man-made or natural. Most of all, let's make sure we marginalize the crooks trying to fleece the global population into paying taxes and falling under their self-proclaimed new world order.

    Gerhard Adam
    The "we" you're referring to are the political leaders that you don't trust (and neither do I).  The rest of the people won't do anything because they're too busy calling either other names and cheerleading for their respective "blue" or "red" masters.

    Until people start engaging in real dialogues with each other about problems and solutions, then this carnival will continue.
    Mundus vult decipi