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900 Pinatubos don’t make an ice age – research 23 February 2010

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Environmental Research Web Blog on some research published in J. Geophys. R. last year:

Robock and colleagues injected 300 ‘Pinatubos’ of SO2 into the baseline run of their models, but also tried amounts as great as 900 Pinatubos. With a dynamic vegetation module, they explored the feedback on global temperatures of widespread death of vegetation due to the volcanic cooling. The feedback was not very impressive. Precipitation dropped markedly, but cooling reached about 10 degrees at most, and recovery was nearly complete after about a decade.

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Thanks a bunch, Alun 23 February 2010

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‘I wouldn’t mind a big volcanic eruption – that would give us a two year respite from global warming and might just help us get to action which the Copenhagen summit didn’t get to.’

That’s Alun Anderson, former editor of New Scientist and author of After the Ice: Life, Death and Geopolitics in the New Arctic (2009), a book that has a picture of a polar bear on the front. He is interviewed in The Ecologist, and can be seen in the accompanying illustration standing on top of a mountain in Greenland, far above the level of common humanity.

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Toba eruption deforested India 24 November 2009

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The Toba eruption of ~73000 years ago is perennially fascinating: the world’s largest known Quaternary eruption, this event registered VEI=8 and had a global climatic impact that may have caused the near-extinction of humanity by creating a ‘population bottleneck’ (or perhaps not). The scientist behind the population bottleneck theory, University of Illinois anthropology professor Stanley Ambrose, is a lead author for a new study in the journal Palaeogeography, Palaeoclimatology, Palaeoecology (click here for the abstract) which explores further the impact of the Toba eruption and concludes that its effects were indeed wide-ranging and (crucially for the claim that contemporary human populations were dramatically affected) long-lasting.

The study looked at pollen from a marine core taken in the Bay of Bengal which includes ash from the Toba eruption and at carbon isotope ratios in fossil soil carbonates from directly above and below the Toba ash in three locations in central India. Both analyses indicated a change in the vegetation cover in central India after the Toba eruption, from forests to more open vegetation conditions with a predominance of grasslands. The change in vegetation suggests that significantly drier conditions were produced by the Toba eruption, and that those conditions lasted for at least a thousand years.

  • Martin A.J. Williams, Stanley H. Ambrose, Sander van der Kaarsc, Carsten Ruehlemannd, Umesh Chattopadhyayae, Jagannath Pale & Parth R. Chauhanf, Environmental impact of the 73 ka Toba super-eruption in South Asia, Palaeogeography, Palaeoclimatology, Palaeoecology [article in press, corrected proof], doi:10.1016/j.palaeo.2009.10.009 (abstract)

Supervolcano eruption – in Sumatra – deforested India 73,000 years ago – EurekAlert, 23 November 2009
Supervolcano eruption in Sumatra deforested India 73,000 years ago – ScienceDaily, 23 November 2009
…. both of the above being essentially regurgitations of this University of Illinois press release.

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‘Compelling evidence’ discovered of previously unknown volcanic eruption, 1809 AD 31 October 2009

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News that a U.S./French team of chemists claim to have found ‘compelling evidence’ of a previously unknown volcanic eruption that occurred 1809 and that may have been responsible for the global cooling noted during the period 1810-19. The evidence comes from ice samples from Greenland and the Antarctic:

‘We’ve never seen any evidence of this eruption in Greenland that corresponds to a simultaneous explosion recorded in Antarctica before in the glacial record’, said Mark Thiemens, Dean of the Division of Physical Sciences at UC San Diego and one of the co-authors of the study. ‘But if you look at the size of the signal we found in the ice cores, it had to be huge. It was bigger than the 1991 eruption of Mount Pinatubo in the Philippines, which killed hundreds of people and affected climate around the world’.

Read on: ‘Previously unknown volcanic eruption helped trigger cold decade’ (UC San Diego news release, 27 October 2009).

[H/T: commenter Perry.]

UPDATE. The 1809 eruption may be unidentified but it’s certainly not ‘unknown’: see comments below.

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