IMAGe Brown Bag- Extreme Tropical Volcanic Eruptions: a Statistical Analysis of Geophysical Data

06/03/2016 - 12:00pm to 1:00pm

Alexandre Tuel
École Polytechnique

One of the major unknowns in climate projections for the next century is natural forcing. While anthropogenic forcing can be estimated through carbon dioxide emissions, natural forcings are much harder to assess. One of these main influences on climate is explosive volcanism. Large explosive eruptions such as the Pinatubo (1991), Krakatau (1883) or Tambora (1815) events, release a considerable amount of SO2 into the lower atmosphere, as well as ashes, which can perturb the radiative balance and lead to global cooling. As an example, the Tambora eruption has been shown to have led to a global cooling of -0.53°C(and the temperatures dropped by as much as 3.5°C over Western Europe.

We will focus on tropical eruptions: since they release gas and ashes in the areas that get the most sunlight, they are the most likely ones to affect climate on a global scale. By comparison, extreme eruptions in the high latitudes will lead to cooling also, but to a more restricted extent. So it is particularly important to predict the occurrence of tropical extreme eruptions for the next century for global volcanic forcing to be as accurate as possible.

Previous research based on extreme eruptions data from polar ice cores sulfate measurements identified a strong 76-year cycle in the likelihood of extreme volcanic eruptions, which has remained unexplained since. Other authors also argued that there unquestionably were periodic variations in tropical volcanic activity, but again, no convincing explanation was found to account for it. The goal of this study is to analyze new datasets of volcanic eruptions to confirm or not the existence of such strong periodic variations, and to look at other geophysical phenomena that could account for cyclic global volcanic activity. We shall more specifically look at the length of day and earthquake activity, which also display strong cyclic variations that correlate well with volcanic data.

Friday, June 3, 2016
12:00-1:00 pm
Mesa Lab, Chapman Room
(Bring your lunch)