November 5, 2012

Toba supervolcano matched with ice cores

No ashes or tephra was found in the ice sheets of Greenland or Antarctica but the supervolcano left other marks in form of very large acidity spikes (sulphates), etc:

Source: Science Daily


As you probably know, Toba caldera is located in Sumatra and its explosion was surely the largest supervolcano ever experienced by Humankind, leading to particularly cold period. 

We know since Petraglia 2007[PPV] that peoples with an African-derived techno-culture lived in South Asia before and after the dramatic episode. However it is unclear how exactly the volcano affected our ancestors beyond that.


Reference paper:

A. Svensson et al., Direct linking of Greenland and Antarctic ice cores at the Toba eruption (74 kyr BP). Climate of the Past, 2012. Open access ··> LINK [doi:10.5194/cpd-8-5389-2012]
 

4 comments:

  1. "...after the dramatic episode"

    I very stongly contest that the tools found above the Toba layer were distinct from earlier stages; rather they were pre-Toba tools eroded and lifted above the ash deposited in the valley. There may have been people around, but the tools found don't prove that.

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  2. I think the most important points of this paper are the synchronization of the arctic and antarctic polar ice cores at this early time, and a much improved dating of both the ice cores and the Toba eruption (74ky bp).

    In the context of human (re-)colonization, it is also of interest that the Toba-initiated global cooling has only about a century duration, while of course the climate remained dry and cold in the northern hemisphere for much longer, due to other reasons causing and extending the past glacial period.

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    Replies
    1. "... it is also of interest that the Toba-initiated global cooling has only about a century duration"...

      Only? I missed that probably because I went just too fast over this paper.

      What's the logic behind that claim because one can easily look at a temperature proxies' graph like this one and imagine that Toba was behind the lengthy cold period before the relative warming of c. 60 Ka. ago. Judging from the Greenland and Antarctic cores that was a very cold period comparable in everything to the depths of the Upper Paleolithic culminating in the LGM, but even longer in duration (with the sole exception of two brief warm interstadials).

      Why was not this caused by Toba and, if so, what caused it instead?

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  3. I think the gist is that this indeed was a very cold and dry period, even more so for the northern hemisphere, for 10,000 years in the short run, and 60,000 years long-term - regardless of Toba short-term inputs.

    This is not to say that those ~100 years were not devastating in terms of exceptional cold, lack of sunlight, acid rain, volcanic deposits, and huge local extinctions of plant and animal species.

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