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New data from Greenland ice cores suggest North America may have suffered a large cosmic impact about 12,900 years ago. A layer of platinum is seen in ice of the same age as a known abrupt climate transition, US scientists report. The climate flip has previously been linked to the demise of the North American "Clovis" people. The data seem to back the idea that an impact tipped the climate into a colder phase, a point of current debate. Rapid climate change occurred 12,900 years ago, and it is proposed that this is associated with the extinction of large mammals...

Greenland ice core analysis shows drastic climate change near end of last ice age Caption: The North Greenland Ice Core Project camp. Credit: NGRIP Temperatures spiked 22 degrees F in just 50 years, researchers say 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...

Following the discovery of the 19.2-mile wide Hiawatha impact crater beneath the northwest margin of the Greenland Ice Sheet, Dr. Joe MacGregor of NASA’s Goddard Space Flight Center and colleagues explored satellite and aerogeophysical data in search of additional such craters and found a possible second impact crater that is 22.7 miles wide and 114 miles southeast of the Hiawatha crater. The discovery is described in a paper in the journal Geophysical Research Letters. ..." Following the finding of that first crater, Dr. MacGregor and co-authors checked topographic maps of the rock beneath Greenland’s ice for signs of other craters....

An international team of geoscientists from the United States, Canada and Europe has discovered a large impact crater beneath the Hiawatha Glacier in remote northwest Greenland. A paper on the discovery was published in the journal Science Advances. The Hiawatha impact crater is approximately 19.2 miles (31 km) wide and lies under an ice sheet that is 0.6 miles (1 km) thick.The scientists believe this crater was formed by a 0.6-mile wide iron asteroid that slammed into the Earth at the end of the Pleistocene epoch, perhaps as recently as 12,000 years ago. ..." “Researchers were looking at the map...

On a bright July day 2 years ago, Kurt Kjær was in a helicopter flying over northwest Greenland—an expanse of ice, sheer white and sparkling. Soon, his target came into view: Hiawatha Glacier, a slow-moving sheet of ice more than a kilometer thick. It advances on the Arctic Ocean not in a straight wall, but in a conspicuous semicircle, as though spilling out of a basin. Kjær, a geologist at the Natural History Museum of Denmark in Copenhagen, suspected the glacier was hiding an explosive secret. The helicopter landed near the surging river that drains the glacier, sweeping out rocks...