Volcanism, Impacts and Mass Extinction: 150 Scienctists conclude on causes and effects
150 Scientists conclude: volcanism is major cause in four out of five of Mass Extinctions, Chicxulub impact a contributing factor in end-Cretaceous Mass extinction
This conclusion was reached at a multidisciplinary international conference on "Volcanism, Impacts and Mass Extinctions: Causes and Effects” held on March 27-29, 2013, at the Natural History Museum of London. The meeting brought together 150 experts from diverse fields across geosciences and astronomy to assess, discuss and evaluate research in this field over the past several years. The outcome of this meeting is historic and marks a turning point in mass extinction debates. The over 30 years of highly contentious and acrimonious mass extinction controversy dominated by the belief that a large impact on Yucatan (Chicxulub) was solely responsible for the mass extinctions, including the dinosaurs at the end of the Cretaceous 65.5 m.y. ago appears to have ended. Massive volcanic eruptions and their environmental effects are considered the most likely main causes of mass extinctions for the end-Cretaceous, end-Pemian, Triassic/Jurassic and end-Devonian mass extinctions.
CONFERENCE REPORT ON:
VOLCANISM, IMPACTS AND MASS EXTINCTIONS:
CAUSES AND EFFECTS
March 27-29, 2013
The Natural History Museum in London recently hosted an international, multi-disciplinary conference that brought together 150 researchers in geology, geophysics, geochemistry, volcanology, sedimentology, paleontology and astronomy to review and assess recent research into the causes of mass extinction events. Participants included seasoned experts as well as younger researchers and students. Through listening and learning from each other and by spirited constructive discussions, a new, collaborative and multi-disciplinary approach to resolving outstanding problems in this field was explored. The data and concepts presented and discussed at the meeting also have value well beyond the geosciences, particularly with regard to understanding modern environmental crises.
The main conclusions of the conference were:
Large igneous province volcanism, along with associated climate and environmental changes, is likely to have played a significant role in at least four of the five major mass extinctions in earth history: the end-Cretaceous, end-Triassic, end-Permian (comprising two distinct extinction events) and end-Devonian. However, the exact causal mechanisms by which 50-90% of the species preserved in the fossil record went extinct at each event remains to be worked out. Better age control for individual lava units and extinction events is critical to establish the relationship between the causes and effects.
There was overwhelming agreement that a single large asteroid or comet impact (Chicxulub) could not have been the sole cause of the end-Cretaceous mass extinction, but rather was a contributing factor. The long-term biological, environmental and climatic changes before, at and after the bolide impact horizon call for a multi-causal scenario, certainly involving volcanism and possibly multiple impacts or comet showers.
Participants gained an improved understanding of how large igneous province eruptions affect the biosphere. This included data and conclusions derived from atmospheric chemistry, geochronology of eruptions, associated mechanisms of climatic changes and the direct effects on species-level extinctions.
Mass extinction patterns can tell us much about the age, tempo and nature of the catastrophe and the type of environments that were most affected. We know most about the end-Cretaceous mass extinction. However, similarly detailed records are still needed for the other mass extinctions. If common patterns, or critical differences, between all mass extinctions are found these can yield critical evidence for or against specific extinction mechanisms.
Ultimately, the effects of volcanism, impacts, sea-level and climate changes (warming and cooling), ocean acidification, ocean anoxia and atmospheric changes have to be considered in any extinction scenario in order to understand the causes and consequences of mass extinctions. Moreover, these data hold keys to help us understand, and cope with, the looming environmental and extinction crises in the modern world.
A planned GSA Special Paper will serve not only as a lasting record of the meeting, but will also act as important guide for the multi-disciplinary studies still needed to resolve the outstanding problems in understanding the causes and effects of mass extinctions. See also Keller et al. (2013): http://www.geolsoc.org.uk/Geoscientist/Archive/November-2012/Volcanism-impacts-and-mass-extinctions-2
Conference Scientific Committee:
Gerta Keller, Princeton University
Andrew Kerr, Cardiff University
Norman MacLeod, The Natural History Museum
Thierry Adatte, University of Lausanne