Taking Earth's volcanic pulse: understanding global volcanic hazards by unlocking the ice core isotope archive

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Explosive volcanic eruptions spew enormous quantities of ash and gas into the atmosphere. There are about 5-10 major volcanic events every year, and roughly 700 million people (10 % of the world's population) live close enough to be directly affected when they erupt. These eruptions may lead to significant human fatalities, and can also have devastating environmental impacts, covering the landscape in ash and acidic fallout, which destroys crops and harms livestock.Although most of us in the UK will never witness one of these eruptions up close they can still impact our lives. This was demonstrated by the eruption of Eyjafjallajökull volcano in Iceland in April and May 2010. Although the eruption was relatively minor and did not kill anyone, it disrupted the travel of millions of people and cost global economies billions of pounds. This emergency highlighted the vulnerability of our global trade and transport networks, and the fact that the UK is at constant threat from disruption by volcanic events. One of the key goals of volcanology is to study past volcanic events so that we can understand their return periods and environmental impacts, and help prepare society for the next 'big one'. Amazingly, the volcanic products from large explosive eruptions undergo regional and global distribution and can travel thousands of kilometres from their eruption source. However, in most surface environments this fine grained volcanic fallout is rapidly washed away and lost. Ice sheets are the expedition to this, and by drilling into the ice and extracting ice cores scientists can identify the sulphur-rich layers and ash deposited by these past eruptions. Although ice cores provide the undisputed best archive of past volcanism, interpreting this record is not straightforward. The main difficulties we face are understanding where the source volcano was located and what its climate impact might have been. Even in records that span the last 2500 years, we only know the location of 7 of the 25 largest volcanic eruptions. If scientists could learn how to extract more information about the likely source and environmental impacts of these eruptions from these records it would represent a major breakthrough. Not only would this help scientists target volcano monitoring in regions of the globe that are prone to large volcanic events, but by understanding the frequency and impacts of these past events we can prepare societies for future eruptions and reduce their economic impacts.My project will take advantage of recent analytical breakthroughs in ice core research. In particular, recent analyses suggest that volcanic sulphur chemistry encodes critical information about the height the volcanic plume reached in the atmosphere and the proximity of the eruptive source to the ice sheet. This method would therefore provide critical new information about where the volcano was located and its climate impact (since plumes injected higher into the atmosphere tend to cause the greatest global cooling). I will carefully interrogate these techniques for several well-known volcanic eruptions, where we already have good information on their source location, eruption style and climate impacts. Once calibrated, I will use this chemical fingerprinting technique to determine the eruptive style (plume height) and source location of all significant eruptions over the last 2000 years. Thus, this project will provide critical information about the magnitude, frequency and style of past eruptions which will be used to improve forecasts of future volcanic events. Being better prepared will help limit the loss of life and reduce the economic losses. For the UK, we'll gain a thorough understanding of the eruption frequency of large volcanic events in Iceland. For global society, we'll help pinpoint the source of past eruptions and evaluate the frequency of climate-changing eruptions on Earth.