Continental destruction, 7 of every 10 people die

That's what happened to North America, according to a team of scientists who say that a large comet exploded over eastern Canada almost 13,000 years ago. Science News Online reports,

Evidence unearthed at more than two dozen sites across North America suggests that an extraterrestrial object exploded in Earth's atmosphere above Canada about 12,900 years ago, just as the climate was warming at the end of the last ice age. The explosion sparked immense wildfires, devastated North America's ecosystems and prehistoric cultures, and triggered a millennium-long cold spell, scientists say. ...

Heat from the event would have set off wildfires across the continent, the scientists suggest. The heat and shock from the explosion probably broke up portions of the ice sheet smothering eastern Canada at the time, they add. The flood of fresh water into the North Atlantic that resulted would have interrupted ocean currents that bring warmth to the region, and thick clouds of smoke and soot in the air would have intensified cooling across the Northern Hemisphere.

It's been recognized for a long time that at this time the glaciers were in retreat, but that this warming period was followed by a 1,000-year-long mini-ice age, referred to as the Younger Dryas. New Scientist reports

But by 12,900 years ago, the ice had retreated sufficiently from the northern Atlantic coast to let meltwater rush suddenly eastward. As an estimated 9500 cubic kilometres of fresh water poured into the Atlantic, it switched off the ocean's salinity-driven "conveyor belt" current, shutting down the Gulf Stream that carries heat from the tropics to eastern North America. It was this that triggered the Younger Dryas cooling, say many palaeoclimate experts.

However, some of the comet proponents now propose a different trigger for the cold spell. The massive airbursts over Canada could have destabilised the continental ice sheet, opening new drainage channels to the east. Additionally, dust and debris from the explosions may have darkened the ice, absorbing solar heat and accelerating melting.

But the worst consequence of the cataclysm was the mass extinctions of the late Pleistocene that have heretofore been attributed to overhunting by the Clovis peoples of the continent. The extinctions were additionally blamed on the Younger Dryas. The new impact theory, though, says that the comet's multiple explosions (caused by its breakup in the high atmosphere) themselves caused the extinctions: "at least 35 genera of the continent's mammals went extinct – including mammoths, mastodons, camels, ground sloths and horses." That's 35 whole genera, not just species, that died out. Just at the time of the extinction the researchers found a significant band of soot in sediments from widely-separated sites.

[T]eam members say this suggests the cometary explosions ignited wildfires that swept across much of southern North America, wiping out large populations of animals. "I don't want to sound catastrophic here," he says, "but this is wild stuff. There is significant evidence of massive biomass burning."

That is, the genera that perished were burned alive. Based on this and other archaeological evidence, researchers say that 70 percent of the human beings in North America were killed as well. The Clovis cultures disappeared.

But did the stories of the remnant remaining survive to this day? Perhaps:

The Ojibwa of the upper Great Lakes region had a story about Genondahwayanung, which meant "Long Tailed Heavenly Climbing Star." During the 1980s, Thor Conway visited the Ojibwa and talked to Fred Pine, an Ojibwa shaman. Pine's story about the creation notes that Genondahwayanung was a star with a long, wide tail which would return and destroy the world someday. He said, "It came down here once, thousands of years ago. Just like a sun. It had radiation and burning heat in its tail." The comet was said to have scorched the earth so that nothing was left, except the native Americans, who were warned ahead of time by Chimanitou, a Holy Spirit, and had gone to a bog and rolled themselves up in the mud to protect themselves from the heat. Pine continued, "It was just so hot that everything, even the stones, were cooked. The giant animals were killed off. You can find their bones today in the earth. It is said that the comet came down and spread his tail for miles and miles." Thereafter, all comet and meteors were treated as serious omens which required the interpretation of the Ojibwa shamans.

There are other stories of a great fire coming from the sky and destroying everything except for certain native American tribes. In some cases the tribes claimed they were warned, while others claimed they just ran for the nearest bodies of water.

The Indian legends are congruent with the comet theory, especially in the suddenness of the destruction.