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Toba eruption deforested India 24 November 2009

Posted by admin in climate, current research, India, Indonesia, Toba.
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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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A volcanic miscellany: Ibu, Toba, Kasatochi, Cotopaxi 21 August 2009

Posted by admin in Alaska, Ecuador, Ibu, Indonesia, Kasatochi, Toba, United States, volcano tourism.
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Catching up with some volcanic bits and bobs that have been hanging around on my desktop/in my inbox/on little pieces of paper in my pocket for the last couple of weeks:

Heightened alert at Ibu. The alert level for the Indonesian volcano Ibu on the island of Halmahera was raised to level 3 (orange/siaga) on 5 August. The last increase in alert level, from 1 (green) to 2 (yellow/waspada), was less than a month earlier, on 15 July. Eruptions of incandescent material accompanied by elevated seismicity occurred with increasing frequency at the end of July. Meanwhile, the lava dome continues to grow. Some very nice pictures of the dome from August 2007 can be found in this Flickr collection (thanks to Volcanism Blog reader Bruce S. for letting me know about this).

Weather wonders and supervolcanoes. Randy Cerveny, geographical sciences professor at Arizona State University, has a new book out called Weather’s Greatest Mysteries Solved! (the exclamation mark is, apparently, part of the title) which looks at the role of the weather in Earth’s prehistory and history, from the extinction of the dinosaurs to the Dust Bowl of the 1930s via the end of the Mayan civilization and the parting of the Red Sea. One chapter is devoted to the Toba eruption of about 74000 years ago, which may (or may not) have brought about the near-extinction of humanity. This topic naturally leads to speculation about possible future ‘supervolcano’ eruptions and the potential threat posed by Yellowstone: ‘It’s overdue’, says Prof. Cerveny, but ‘I don’t think it’s a run into the night screaming kind of thing yet, but if it were to happen civilization as we know it would probably break down’. He also has a nice message of humility for humanity, pointing out that however much ‘We like to think we are masters of our fate … the thing about climate is that there are simply a lot of things we can’t control or even begin to control or totally understand’.

‘Our island blew up’. The August 2008 eruption of Kasatochi volcano in the Aleutians brought an abrupt end to scientific fieldwork being carried out there by two U.S. Fish & Wildlife Service biologists: ‘our island blew up’, is the deadpan observation in their research report. Today Kasatochi, formerly green here and there, is black and barren, and about 32 percent larger than it was before the eruption. A scientific team is revisiting the island to assess the aftermath of the event, and will be accompanied by a reporter from the Alaska Daily News who will file regular reports on their researches.

Music and dance at Cotopaxi. It’s 34 years since the Cotopaxi National Park was created around Cotopaxi volcano in Ecuador, and local communities have been celebrating the anniversary with music and dance, reports El Comercio. The Ecuadorian Minister for the Environment has been at the celebrations, and the locals have taken the opportunity to lobby her for more support and funding for the park and the people who live in and around it. The Parque Nacional Cotopaxi is one of Latin America’s top tourist attractions, receiving more than 100,000 visitors per year.

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