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The initial trigger to the melt: A small and predictable wobble in Earth's orbit around the sun. That tiny wobble meant a tilt toward the sun that brought more sunlight in the Northern Hemisphere, causing ice sheets to melt and sending whopping levels of fresh water into the world's oceans. That caused the global circulation of the oceans to stop, which in turn warmed the southern oceans, melting southern ice sheets over areas where more of the world's carbon dioxide is trapped, Shankun said. That released massive amounts of the greenhouse gas, which then amplified the global temperature spike, Shankun said. By 11,000 years ago, the ice age was history and greenhouse gas and temperature levels had stabilized. That changed with the industrial age and the increased use of fossil fuels. Carbon dioxide levels have jumped roughly the same amount in the last century as they did over 6,000 years to get out of the ice age, Shankun said. Penn State University professor Richard Alley and others called this a significant advance in studies about past climate change and carbon dioxide, saying "this may be of help in explaining things out in the sound-bite world." ___ Online: Nature: http://www.nature.com/nature/
[Associated
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