ORONO – Two University of Maine scientists will be featured at 8 p.m. Tuesday, March 31, on the PBS primetime series “NOVA.” The segment, “Last Extinction,” follows prominent scientists as they explore the idea that a comet striking the Earth is to blame for the extinction of giant mammoths and other large animals, and the destruction of several hunter-gatherer communities at the end of the Ice Age.

“NOVA” reports on the scientist’s latest round of research on the Greenland ice sheet, carried out by Paul Mayewski, director of UMaine’s Climate Change Institute, and by Andrei Kurbatov, an assistant research professor with UMaine’s Climate Change Institute.

“The abrupt change in climate that occurred 12,900 years ago has undergone extensive study because of its implications as an analog for future climate, but we’ve added some new complexities and understanding to it,” Mayewski said, referring to the comet-impact hypothesis.

The hypothesis that a comet struck Earth is supported by unusual discoveries in a distinctive soil layer known as the “black mat,” found at more than 50 sites across North America.

Within the same time period of the Greenland ice sheet, Mayewski states that he, with colleagues Allen West and Jim Kennett, found the presence of nanodiamonds, which are believed to have been created by the extraterrestrial impact.

On the PBS Web site, Mayewski likens the search for these nanodiamonds to “worse than looking for a needle in a haystack.”

But their search was successful.

“It’s the first time people have found nanodiamonds in an ice sheet that are created during meteorite impacts,” Mayewski said. “In this layer on the ice sheet, one cup of water contains billions of these nanodiamonds.”

This event is believed to be the last time the Earth was struck by a major meteorite, and according to Mayewski, it may have been important in triggering a cold period that lasted for about 1,200 years.

UMaine became involved in NOVA’s project because Mayewski led a past project that discovered abrupt climate change events and documented in detail the characteristics of the 12,900 years ago event.

“The reason that this event is so important is because it coincides with the extinction of a lot of large mammals, such as saber tooth tigers and mammoths,” Mayewski said. “It’s also an example of what a nuclear winter could be like.”

For more information on the show, visit www.pbs.org/nova/clovis.

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