The theme for the webinar series is: "Worst-case thinking: Past eruptions and volcanic risk analysis"
Friday 26 March 15:00 UTC
Co-chairs: Francis Ludlow and Matthew Toohey
First speaker: Michael Sigl, Oeschger Centre for Climate Change Research: "Insights on the timing, sulfur injection and climate impact of volcanic eruptions over the Holocene from a polar ice-core array"
Volcanic eruptions have been identified as a primary driver of climate variability, impacting surface air temperature, atmospheric circulation and hydroclimate. The observational record of the timing of volcanic eruptions, their location, magnitude of sulfate aerosol injection and its atmospheric life-cycle, however, is often incomplete, with gaps in our record of past volcanic activity increasing dramatically before the Modern (pre-1800) era.
Here, I discuss new glacio-chemical and geochemical evidence extracted from an array of polar ice cores on the timing, SO2 emissions and climate impact of past eruptions. I present a database providing estimates of stratospheric sulfur injection versus latitude and time over the Holocene, thus providing the basis for a continuous reconstruction of volcanic radiative forcing for climate model simulations.
Second speaker: Johann Jungclaus, Max Planck Institute for Meteorology: "Impact of fast-varying external forcing on climate variability in transient simulations over the Holocene"
Most existing transient simulations covering the Holocene have focused on orbital changes or included the slowly varying changes of greenhouse gases (GHG). Here we present results from two transient simulations covering the Holocene from 8kyr BP to 1850 CE using the comprehensive Earth system model MPI-ESM1.1. While one of our simulations is forced only by orbital parameters and changes in GHG concentrations, the other includes additional forcing agents: volcanic aerosols, variations in solar irradiance, and (for the late Holocene) changes in land-cover and land-use.
Comparing the two simulations highlights in particular the effects of strong volcanic eruptions. In addition to the direct cooling effects by volcanic eruptions we diagnose sustained changes in trends, and circulation patterns in ocean and atmosphere, as well as sea-ice cover. Feedbacks between these compartments introduce long-lasting variations in particular in Northern Hemisphere climate. Over the Holocene, including the “fast” varying forcing agents introduces not only events of climate change, but also changes the spectral characteristics of climate indices and variability modes. This could potentially explain discrepancies between reconstructions and existing climate model simulations that have traditionally only included orbital changes.
How to join
Meeting ID: 966 7788 8866
There is no need to register and it is free to join.
Past webinars in the series
Friday 26 February 15:00 UTC
First speaker: Gordon Woo, University College London: "Reimagining Volcanic History: Lessons from counterfactual analysis"
As with other extreme natural hazards, the record of volcanic eruptions is sparse. More can be gleaned from this record by adopting the physicist’s perspective that history is just one realisation of what might have happened. By reimagining history, especially periods of volcanic unrest, fresh insight can be gained into volcano risk. Counterfactual volcano risk analysis is illustrated by the example of Montserrat. The fundamental concept of counterfactual analysis is universal and applies to all perils, both natural and man-made, including pandemics.
Second speaker: Amy Donovan, University of Cambridge: "Imagining volcanoes: towards a holistic understanding of risk"
This presentation will discuss some of the challenges that scientists face in communicating risk and working with governments. It will focus on the many ways that groups of people can "view" the volcano and its potential activity – from scientists to local populations – and discuss the particular difficulties that arise when multiple governments are involved across borders. Ultimately, I will argue that this requires volcanologists to understand their own positionality and work across disciplinary boundaries.