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Earth Science

What Caused a 1300-Year Deep Freeze? 258

Posted by Unknown Lamer
from the should-have-discovered-coal-earlier dept.
sciencehabit (1205606) writes "Things were looking up for Earth about 12,800 years ago. The last Ice Age was coming to an end, mammoths and other large mammals romped around North America, and humans were beginning to settle down and cultivate wild plants. Then, suddenly, the planet plunged into a deep freeze, returning to near-glacial temperatures for more than a millennium before getting warm again. The mammoths disappeared at about the same time, as did a major Native American culture that thrived on hunting them. A persistent band of researchers has blamed this apparent disaster on the impact of a comet or asteroid, but a new study concludes that the real explanation for the chill, at least, may lie strictly with Earth-bound events."
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What Caused a 1300-Year Deep Freeze?

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  • by Anonymous Coward on Monday May 12, 2014 @07:52PM (#46985283)

    Tundra soil is not particularly fertile and the processes that enrich soil can take hundreds if not thousands of years. I suppose if you have enough compost to cover Canada and such.

    and that ignores the obvious desertification that would happen across huge swathes of currently productive land.

  • by Layzej (1976930) on Monday May 12, 2014 @08:10PM (#46985397)
    "The prevailing theory is that the Younger Dryas was caused by significant reduction or shutdown of the North Atlantic "Conveyor", which circulates warm tropical waters northward, in response to a sudden influx of fresh water from Lake Agassiz and deglaciation in North America. Geological evidence for such an event is thus far lacking. The global climate would then have become locked into the new state until freezing removed the fresh water "lid" from the north Atlantic Ocean. An alternative theory suggests instead that the jet stream shifted northward in response to the changing topographic forcing of the melting North American ice sheet, bringing more rain to the North Atlantic which freshened the ocean surface enough to slow the thermohaline circulation. There is also some evidence that a solar flare may have been responsible for the megafaunal extinction, though it cannot explain the apparent variability in the extinction across all continents." - http://en.wikipedia.org/wiki/Y... [wikipedia.org]
  • by GPS Pilot (3683) on Monday May 12, 2014 @08:16PM (#46985431)

    It's interesting that this comes on the same day that low-information journalists are panicked because "the melt that has started could eventually add 4 to 12 feet to current sea levels. [detroitnews.com]"

    Apparently they're not aware that this is trivial compared to what nature dishes out. During the Last Glacial Maximum (only ~23,000 years ago), sea level was 400 feet lower than it is today.

    Every species that's alive today, including polar bears, managed to survive that massive 400-ft increase in sea level.

    In fact, every species that's alive today has managed to survive dozens of glacial advances and glacial retreats -- each one of which caused massive fluctuations in sea level.

    The low-information voters and low-information journalists also seem unaware that the natural and normal state of the earth is to not have any polar ice caps whatsoever. The only reason Earth currently has polar ice caps is because the Quaternary glaciation (i.e., the most recent ice age) is not completely over; we are still emerging from it.

  • Waste of time (Score:5, Informative)

    by scribble73 (879745) on Monday May 12, 2014 @08:19PM (#46985449)
    This headline promises a lot, but delivers nothing. The article just looks briefly at the controversy -- in other words, we still don't know.

    This comes from a good Journal, but reading it was a waste of time.
  • Not really much here (Score:5, Informative)

    by x181 (2677887) on Monday May 12, 2014 @08:43PM (#46985605)
    Old Argument (Younger Dryas): We found iridium (rare on earth but abundant in meteorites), nanodiamonds and magnetic particles covering ancient tools and mammoth remains at sites which we believe are around 12,000 years old. Therefore, we believe a cosmic collision caused the 1,300 year deep-freeze.

    New Argument: We performed radiocarbon dating on tools found at the 29 sites described in the Old Argument and found that only 3 of the 29 sites were around 12,000 years old. The tools at other sites were much older or younger. Therefore, the deep-freeze was probably not caused by a cosmic collision.
  • by ColdWetDog (752185) on Monday May 12, 2014 @09:04PM (#46985737) Homepage

    Tundra is marginal for most crops. Tundra is typically a thin, acidic soil. Given a couple of hundred thousand years, it probably would pick up a bunch of new critters and plants and become more organically active, but most of us are not that patient.

  • by TubeSteak (669689) on Monday May 12, 2014 @09:06PM (#46985751) Journal

    Desertification is not 'obvious'. Key to global warming is more water vapor feeding back any heat increases. Likely increased average rain with increased temperature.

    You seem to be making a common mistake when talking about climate change:
    You're confusing global "average rain" with local "average rain."

    We know, without a doubt, that climate change will shift weather patterns and create deserts.
    We're also seeing signs that climate change is shifting weather patterns and greening existing deserts.

    For the sake of argument, let's assume that useless land and useful land switch places in a 1:1 ratio.
    That still leaves one big problem: what do you do with all the people and infrastructure that are in the new desert?
    It's a problem whose only solutions are extremely expensive.

  • by Layzej (1976930) on Monday May 12, 2014 @09:51PM (#46986089)

    During the Last Glacial Maximum (only ~23,000 years ago), sea level was 400 feet lower than it is today.

    Good thing they didn't have any coastal cities 23,000 years ago. That would have sucked.

    In fact, every species that's alive today has managed to survive dozens of glacial advances and glacial retreats

    What about the species that aren't alive today? How did they do?

  • by Anonymous Coward on Tuesday May 13, 2014 @09:21AM (#46988669)

    This is not a agenda free site.
    Amazing that they don't seem to know that the reason there is a process to estimate terrestrial temperature using tress is because a solar astronomer named A. E. Douglass wanted sun spot data for periods from before modern times when sun spot data was recorded. He worked out that because sun spot activity effected climate, which resulted in larger tree rings for years with high sun spot activity, that he could use old growth trees to determine sunspot activity for earlier periods.
    Later in the 1990s climate change supports started using his data, which he had already proved was linked to sunspot activity to support AGW. How did he prove his theory? He used the scientific method. He compared periods of known correlation and then predicted future activity. When his prediction came true he then used what he had learned to map previous sunspots periods. So climate is linked to sun spot activity. You can even see it now. the early 2000s was a low sunspot activity period, and there was no average temperature rise. The 1930s were high sunspot activity periods. The 1930s were warmer than the 1990s'
    Climate scientist could learn a lot from A.E. Douglass, since their methods seem to be ignore data that doesn't fit the hypothesis, create models that don't really match predictions, and blame people who then don't believe you.

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