Skip to comments.Did comet start deadly cold snap?
Posted on 05/16/2007 3:00:33 PM PDT by Mike Darancette
An extraterrestrial impact 13,000 years ago wiped out mammoths and started a mini-ice age, scientists believe
Margaret Munro CanWest News Service
Monday, May 14, 2007
A comet or some other extraterrestrial object appears to have slammed into northern Canada 12,900 years ago and triggered an abrupt and catastrophic climate change that wiped out the mammoths and many other prehistoric creatures, according to a team of U.S. scientists.
Evidence of the ecological disaster exists in a thin layer of sediment that has been found from Alberta to New Mexico, say the researchers, whose work adds a dramatic and provocative twist to the decades-old debate about the demise of the mammoths, mastodons and sloths that once roamed North America.
The sediment layer contains high concentrations of iridium, fullerenes and other compounds associated with space rocks and impacts, says Luann Becker, a geologist at the University of California, Santa Barbara, who has been analyzing the sediments.
"We have evidence for distribution of impact debris over several thousands of miles over the North American continent," says Ms. Becker, whose group will detail the findings at the American Geophysical Union meeting on May 24.
The sediment layer formed 12,900 years ago and coincides with both the extinction of the animals and the onset of a mini-ice age that lasted more than 1,000 years, say Ms. Becker and her colleagues from several U.S. universities and research labs. They say they are increasingly convinced the impact, extinction and cold snap are all related.
According to their scenario, a comet or large meteoroid generated a shock wave and threw massive amounts of debris, heat and gas into the atmosphere. This set off wildfires that raced across grasslands in southern North America, depriving the mammoths and other grazing animals of food.
The impact and heat also destabilized the ice sheet that blanketed Canada at the time, creating a flood of melt water that poured into the North Atlantic, according to their theory. The pulse of fresh water then shut down the ocean currents carrying heat from the tropics to the Northern Hemisphere, leading to an abrupt cooling. The resulting "mini-ice age" in the Northern Hemisphere, known as the Younger Dryas, lasted more than a thousand years.
Until now one of the leading explanations for the disappearance of the mammoths and other animals is that they were hunted to extinction by the people who arrived in North America from Asia at least 13,000 years ago.
But Ms. Becker and her colleagues doubt there could have been enough people to drive the creatures to extinction with spears. "It would have been a real challenge to slaughter all the animals," she says.
The leading explanation for the mini-ice age has been that melt water slowly built up behind the ice dams as the Earth warmed at the end of the last ice age and then suddenly burst, sending fresh water pouring into the North Atlantic.
Skeptics are not convinced an extraterrestrial impact explains either the disappearance of the animals or the mini-ice age, let alone both events.
Climatologist Andrew Weaver of the University of Victoria says the notion that an extraterrestrial impact caused the Younger Dryas "requires an extraordinarily huge leap of faith." He says there were many climate swings during the last glacial cycle; the mini-ice age was simply the last of them and does not require an extraterrestrial explanation.
Geophysicist Jerry Mitrovica at the University of Toronto is also skeptical. "I'll wait to see the published papers," says Mitrovica, who has studied how the melting ice helped trigger the miniice age.
While the idea of a comet impact may seem far-fetched, Mr. Mitrovica notes that it took almost a decade before scientists accepted geologist Walter Alvarez's evidence that the iridiumrich layer he found pointed to the asteroid impact that killed off the dinosaurs 65 million years ago.
Ms. Becker says the details of their findings will likely be published in the science journals this summer. Meantime, she and her colleagues are expecting a "spirited" debate at next week's AGU meeting.
She says the concentration of the iridium in the sediment layer dating back to 12,900 years is several times higher than normal. It also contains compounds called "fullerenes" with extraterrestrial gases in them, as well as glasslike carbons that require extraordinarily high temperatures to form. "It's a very discrete, well-defined layer," she says.
As for the crater created by the impact, the scientists say it would have formed on the kilometres-thick ice that covered Canada at the time and melted away with the ice.
However, in the late 70’s I recall all the literature on the coming ice age. It was very convincing at the time.
Hal Lindsey was quite popular and the population bomb books were all the rage also.
Hard to get excited these days about this stuff, given the sadly inaccurate history of predicted disasters.
Somebody with better internet skills needs to find that cover. Which cover? I think it had to be TIME or Newsweek. “The Coming Ice Age” - circa 1979 ?
This is a minor “big one” occurring relatively short time ago affecting mainly the NA continent, in almost historical times.
So arctic melting leads to self correction?
Looks like it, man what a noise that one would have made.
Recorded human civilization has only been around for a few thousand paltry years. Even 200 years ago, life was radically different for humans than it is today. No computers, airplanes, automobiles, telephones, electricity, indoor plumbing, etc.
Forget about global warming and "man-made changes" to the climate. At various intervals, most of North America was covered under thousands of feet of solid ice during the Ice Ages. These times will come yet again no matter how much we cut back on our "emissions" to curb "global warming."
I would like to be given the powers of immortality and go back in time to 25 million years ago. I would like to take with me every book ever published, every music recording ever made and every movie/TV show ever made as well as every bottle of wine and beer ever made just so I will have something civilized to do during those millions of years of non-human civilization. (Of course, I would like a power source to run all these things as well.)
This will allow me to observe the Earth for 25 million years and record everything in detail. Then as human civilization took shape, I would like to be an observer for Ancient Egypt, the Roman Empire, the Middle Ages, the Renaissance and of course, all of U.S. History. I would like to journey with the Pilgrims to New England and be on hand to observe first-hand the entirety of U.S. history.
I would like to drink beer with Benjamin Franklin, go horse riding with George Washington, have a duel with Alexander Hamilton (though not kill him), take in a play with Abraham Lincoln (though stay away from "Our American Cousin") and freak out Albert Einstein by talking about the theory of relativity with him before he even thought of it.
Yeah, all of that would be good fun.
Please send me a FReepmail to get on or off this Canada ping list.
An ice dam broke on the South Shore of a fresh water lake larger than Superior.
It created vast "bad lands" formations in Canada and the United States that can still be seen. The fellow with that theory was actually laughed at until other scientists proved it.
This is just a slightly larger scale thought on the matter for a slightly earlier period of time.
For a small scale version visit Turkey Run state park near Crawfordsville, Indiana. Here a two mile high glacier melted off into a waterfall that ended at this site.
Without those currents the icebergs breaking out of the sea ice wouldn't have gotten much momentum ~ making travel in a small boat relatively safe even in mid-ocean. I would imagine this would even have a serious impact on hurricanes and that would have extended the sailing time into the warmer months giving the Sa'ami plenty of time to reach America.
I think we can come up with a specific date for when the first Europeans could have arrived in America via an Atlantic route now.
Question - what recorded blast started wildfires? Every high temperature blast, that I have seen record of, cooked (sometimes to charcoal) things exposed to them, yet I see no references to fire resulting from them.
There have been a large number of volcanoes that have erupted in recorded history, yet it has only been lava flows that I have heard of starting fires. I believe it was incendiaries, not high explosives that started the firestorms that immolated cities in WWII.
This is Temperate Zone Ice about a mile or so thick.
Think "like Antarctica".
Ms. Becker listened to you.
They could have walked across the ice.