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Tree rings, volcanoes and climate 7 March 2012

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Is dendrochronology always a reliable guide to past climatic variations? And apropos the theory that large volcanic eruptions in the latter half of the thirteenth century AD were responsible for the cool period known as the Little Ice Age (LIA), can it perhaps be argued that the eruption did not so much begin the LIA as end the MWP (Medieval Warm Period)? That kind of conceptual re-focusing appeals to me as a historian. It is the type of game historians (well aware that all periodization is a human construct) like to play: flip the structuring principles you apply to the past around and see what difference it makes. And what do the trees say?

These musings are provoked by this article at Bits of Science. Have a look and see what you think.

The Volcanism Blog

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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Volcanoes to blame for Cretaceous ocean anoxic event 11 February 2010

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Research published in a letter in Nature Geoscience: around 94.5 million years ago volcanism released large volumes of sulphur into the atmosphere which triggered huge phytoplankton blooms, which in turn deprived the oceans of oxygen and triggered extensive marine extinctions. The abstract tells it like this:

During the Cretaceous period (~145–65 million years ago), there were several periods of global ocean anoxia, each lasting less than one million years. These events, known as ocean anoxic events, were marked by significant increases in organic carbon burial, and are generally attributed to increased primary productivity in surface waters. The details underpinning the initiation, maintenance and termination of these events, however, remain equivocal. Here we present sulphur isotope data spanning the Ocean Anoxic Event 2 (about 94.5 million years ago) from sedimentary rocks in Colorado that were formed in the Western Interior Seaway; this seaway ran north–south, splitting North America during the Cretaceous. Sulphate levels increased rapidly from relatively low background levels at the onset of the event, most likely from the release of sulphur by massive volcanism, and fell during the anoxic event. We infer that the input of sulphate facilitated increased carbon remineralization, which enhanced nutrient recycling and increased global primary productivity, eventually resulting in widespread ocean anoxia. Our scenario indicates that Ocean Anoxic Event 2 may have persisted until sulphate levels were stabilized by the formation and burial of the sulphur mineral pyrite, which returned primary productivity to background levels. We suggest that fluctuations in sulphate levels may have regulated the marine carbon cycle during past periods of low oceanic sulphate concentration.

And that is why geoengineering the climate with artificial volcanoes is a really bad idea: ‘Like the mid-Cretaceous ocean, most modern lakes are poor in sulphate, so it’s possible that geoengineering the climate could trigger blooms and ultimately anoxia in some lakes’ says researcher Matthew Hurtgen of Northwestern University. ‘We hack the climate at our peril’, warns New Scientist. ‘Volcanoes spewed so much sulphate into the atmosphere 94 million years ago that the oceans were starved of oxygen and 27 per cent of marine genera went extinct. Geoengineering our climate could inflict a similar fate on some lakes’. Such is the climate change dilemma: in trying to avoid (for example) climate-induced tectonic-volcanic geo-apocalyptic mega-mayhem we may cause geoengineering-induced volcanic-toxic extinction-anoxic mega-mayhem instead. Agh.

  • Derek D. Adams, Matthew T. Hurtgen & Bradley B. Sageman, ‘Volcanic triggering of a biogeochemical cascade during Oceanic Anoxic Event 2′, Nature Geoscience, 31 January 2010 [doi:10.1038/ngeo743]. Abstract.

(There’s more on volcanism triggering the Cretaceous anoxic events in Nature, 17 July 2008, and Ole Nielsen has a great blog post: Late Cretaceous Anoxic Event.)

The Volcanism Blog

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.

The Volcanism Blog

‘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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More on climate change and volcanism from ‘Nature’ 18 September 2009

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The possible connection between climate change and increased volcanism has been attracting some attention recently. Now Nature takes a look at the issue in a news article headed ‘Volcanoes stirred by climate change‘: the point being that a reduction in ice cover may be related to more explosive eruptive activity from volcanoes (or, as Nature calls them, ‘these unstable magmatic beasts’).

Volcanoes stirred by climate changeNature, 17 September 2009

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A geologist looks at geoengineering 15 September 2009

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Geoengineering our way out of climate catastrophe is flavour of the month in certain quarters: mechanical trees, giant sunshades, artificial volcanoes, etc.

Chris Rowan of Highly Allocthonous is not convinced about all this, and has an article about geoengineering at Seed Magazine explaining why. Related posts at Highly Allocthonous here and here.

Business as abnormalSeed Magazine, 14 September 2009

The Volcanism Blog

Climate change: scientists warn of tectonic-volcanic geo-apocalyptic mega-mayhem 6 September 2009

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John Martin, 'The Great Day of His Wrath' (1853)
Above: John Martin’s ‘The Great Day of His Wrath’ (1853). An understatement, if anything.

University College London will be hosting a colloquium on ‘Climate Forcing of Geological Hazards’ from 15-17 September, which ‘will address relationships between past and contemporary climate change and the triggering of hazardous geological and geomorphological phenomena’. We’re looking at a future of earthquakes, avalanches, tsunamis, collapsing mountains and more volcanic eruptions, apparently. The Guardian has a report on the event today, under the headline ‘Global warming threatens Earth with wave of natural disasters’:

Melting glaciers will set off avalanches, floods and mud flows in the Alps and other mountain ranges; torrential rainfall in the UK is likely to cause widespread erosion; while disappearing Greenland and Antarctic ice sheets threaten to let loose underwater landslides, triggering tsunamis that could even strike the seas around Britain. At the same time the disappearance of ice caps will change the pressures acting on the Earth’s crust and set off volcanic eruptions across the globe.

The report quotes the reliably apocalyptic head of UCL’s Benfield Hazard Research Centre, Professor Bill McGuire: ‘Not only are the oceans and atmosphere conspiring against us, bringing baking temperatures, more powerful storms and floods, but the crust beneath our feet seems likely to join in too’.

The Volcanism Blog

Averting climate doom with artificial volcanoes 30 August 2009

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Artificial volcano at the Mirage Hotel, Las Vegas. Flickr image from temptingmamma's photostream, Creative Commons licensed.

Man-made volcanoes may cool Earth reports The Times today: yes, it’s artificial volcanoes again. The idea is to reproduce the sulphur-propagating aspects of volcanic eruptions in order to cool the planet:

The Royal Society is backing research into simulated volcanic eruptions, spraying millions of tons of dust into the air, in an attempt to stave off climate change.

The society will this week call for a global programme of studies into geo-engineering — the manipulation of the Earth’s climate to counteract global warming — as the world struggles to cut greenhouse gas emissions.

It will suggest in a report that pouring sulphur-based particles into the upper atmosphere could be one of the few options available to humanity to keep the world cool.

See also: mechanical trees, slimy buildings, white paint on roofs, cloud-generating ships, artificial plankton blooms, giant space sunshield, wrapping Greenland in a blanket.

[Image of the artificial volcano at the Mirage Hotel, Las Vegas, by temptingmama at Flickr, reproduced here under a Creative Commons license.]

The Volcanism Blog

New sulphur dioxide monitoring methods – improving volcano and climate monitoring 13 March 2009

Posted by admin in climate, current research, geoscience, natural hazards, volcano monitoring, volcanology.
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A press release from the Swedish Research Council reports the work of Matthias Johansson, doctoral student in the Department of Radio and Space Science at Chalmers University in Göteborg, who has developed a system of measuring sulphur dioxide output from volcanoes by aggregating measurements taken from two or more instruments. Much of the work on the project ‘has involved making the equipment sufficiently automatic, robust, and energy-efficient for use in the inhospitable environment surrounding volcanoes, in poor countries with weak infrastructure’. The equipment is currently in use at seventeen locations.

The research also has implications for improved global climate monitoring by providing continuous measurements of the levels of sulphur dioxide emitted into the atmosphere by the world’s most active volcanoes:

‘Sulfur dioxide is converted in the atmosphere to sulfate particles, and these particles need to be factored into climate models if those models are to be accurate’, says Associate Professor Bo Galle, who directed [Johansson's] dissertation. Volcanoes are an extremely important source of sulfur dioxide. Aetna alone, for instance, releases roughly ten times more sulfur dioxide than all of Sweden does.’

The Chalmers research is part of Project Novac, a European Union funded project to establish networks for the measurements of volcanic gases and aerosols, and apply the data obtained to risk analysis and volcanological research, locally and on a regional and global scale.

UPDATE: I missed Ole Nielsen’s post of yesterday on this, at Olelog – Volcanic Eruption Forecasting.

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