• Rewriting the history books: Why the Vik

    From ScienceDaily@1:317/3 to All on Wed Mar 23 22:30:46 2022
    Rewriting the history books: Why the Vikings left Greenland

    Date:
    March 23, 2022
    Source:
    University of Massachusetts Amherst
    Summary:
    One of the great mysteries of late medieval history is why
    did the Norse, who had established successful settlements
    in southern Greenland in 985, abandon them in the early 15th
    century? The consensus view has long been that colder temperatures,
    associated with the Little Ice Age, helped make the colonies
    unsustainable. However, new research upends that old theory.

    It wasn't dropping temperatures that helped drive the Norse from
    Greenland, but drought.



    FULL STORY ==========================================================================
    One of the great mysteries of late medieval history is why did the Norse,
    who had established successful settlements in southern Greenland in 985, abandon them in the early 15th century? The consensus view has long been
    that colder temperatures, associated with the Little Ice Age, helped make
    the colonies unsustainable. However, new research, led by the University
    of Massachusetts Amherst and published recently in Science Advances,
    upends that old theory. It wasn't dropping temperatures that helped
    drive the Norse from Greenland, but drought.


    ==========================================================================
    When the Norse settled in Greenland on what they called the Eastern
    Settlement in 985, they thrived by clearing the land of shrubs and
    planting grass as pasture for their livestock. The population of the
    Eastern Settlement peaked at around 2,000 inhabitants, but collapsed
    fairly quickly about 400 years later.

    For decades, anthropologists, historians and scientists have thought
    the Eastern Settlement's demise was due to the onset of the Little Ice
    Age, a period of exceptionally cold weather, particularly in the North Atlantic, that made agricultural life in Greenland untenable.

    However, as Raymond Bradley, University Distinguished Professor of
    geosciences at UMass Amherst and one of the paper's co- author, points
    out, "before this study, there was no data from the actual site of the
    Viking settlements. And that's a problem." Instead, the ice core data
    that previous studies had used to reconstruct historical temperatures
    in Greenland was taken from a location that was over 1,000 kilometers
    to the north and over 2,000 meters higher in elevation. "We wanted
    to study how climate had varied close to the Norse farms themselves,"
    says Bradley. And when they did, the results were surprising.

    Bradley and his colleagues traveled to a lake called Lake 578, which is adjacent to a former Norse farm and close to one of the largest groups of
    farms in the Eastern Settlement. There, they spent three years gathering sediment samples from the lake, which represented a continuous record
    for the past 2,000 years. "Nobody has actually studied this location
    before," says Boyang Zhao, the study's lead author who conducted this
    research for his Ph.D. in geosciences at UMass Amherst and is currently
    a postdoctoral research associate at Brown University.

    They then analyzed that 2,000 year sample for two different markers:
    the first, a lipid, known as BrGDGT, can be used to reconstruct
    temperature. "If you have a complete enough record, you can directly
    link the changing structures of the lipids to changing temperature,"
    says Isla Castan~eda, professor of geosciences at UMass Amherst and one
    of the paper's co-authors. A second marker, derived from the waxy coating
    on plant leaves, can be used to determine the rates at which the grasses
    and other livestock-sustaining plants lost water due to evaporation. It
    is therefore an indicator of how dry conditions were.

    "What we discovered," says Zhao, "is that, while the temperature barely
    changed over the course of the Norse settlement of southern Greenland,
    it became steadily drier over time." Norse farmers had to overwinter
    their livestock on stored fodder, and even in a good year the animals
    were often so weak that they had to be carried to the fields once the
    snow finally melted in the spring. Under conditions like that, the
    consequences of drought would have been severe. An extended drought, on
    top of other economic and social pressures, may have tipped the balance
    just enough to make the Eastern Settlement unsustainable.

    Scientists at Smith College and the University at Buffalo also contributed
    to the research, which was supported by the National Science Foundation,
    UMass Amherst, the Geological Society of America, and the Swiss National Science Foundation, changes our understanding of early European history,
    and highlights the importance of continuing to explore how environmental factors influence human society.


    ========================================================================== Story Source: Materials provided by
    University_of_Massachusetts_Amherst. Note: Content may be edited for
    style and length.


    ========================================================================== Journal Reference:
    1. Boyang Zhao, Isla S. Castan~eda, Jeffrey M. Salacup, Elizabeth
    K. Thomas,
    William C. Daniels, Tobias Schneider, Gregory A. de Wet, Raymond S.

    Bradley. Prolonged drying trend coincident with the demise of
    Norse settlement in southern Greenland. Science Advances, 2022;
    8 (12) DOI: 10.1126/sciadv.abm4346 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220323151650.htm

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