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Volcanic Forcing in Climate Model Projections: Towards a New Paradigm.

Periodic Reporting for period 1 - VOLCPRO (Volcanic Forcing in Climate Model Projections: Towards a New Paradigm.)

Okres sprawozdawczy: 2020-02-01 do 2022-01-31

Volcanic eruptions inject sulfur gases into the atmosphere which form tiny sulfate aerosol particles that reflect light from the sun, resulting in a reduction of the Earth’s surface temperature. The eruption of Tambora in 1815 was followed by the “Year Without a Summer”, during which starvation affected parts of North America and Europe. Global cooling related to explosive eruptions contributed to a slight slow-down in the rate of anthropogenic global warming over 2000-2014. A major challenge for predicting future climate lies in our inability to predict volcanic eruptions more than days in advance. Consequently, climate model projections assume that volcanic “forcing” on climate, i.e. the impact of volcanic gases on the radiative energy received by Earth, is constant. However, volcanic forcing can vary by a factor 3-4 from one century to another. This large uncertainty is currently ignored. Furthermore, the rise of a volcanic column, the life cycle and transport of sulfate aerosols particles, and the climatic impacts of these aerosols are all sensitive to climate. The assumption of a constant volcanic forcing in a warming Earth is thus flawed. Accordingly, the overarching objective of this project was to develop new strategies to represent volcanoes in climate models. Specifically, the project produced new experiments with the state-of-the-art UK climate model to:
1 – Determine how the climate response to future eruptions will be affected by interactions between volcanoes and anthropogenic global warming.
2 – Determine how a statistically realistic distribution of volcanic eruptions would affect future climate change projections, and the uncertainties on these projections.
This research aims to feed Assessment Reports of the Intergovernmental Panel on Climate Change and, in turn, help global and local societies to face the challenges posed by global climate change.
To reach the first objective, models for the rise of volcanic columns are required to investigate how global warming may affect the distribution of volcanic gases in the atmosphere. These models are critical for managing volcanic crises as they provide predictions for the dispersion and fallout of ash and the occurrence of “pyroclastic flows” (devastating avalanches of burning volcanic rocks). Even relatively minor eruptions can have profound consequences in our globalized world. The ash clouds of the 2010 Eyjafjallajökull eruption disrupted transatlantic flights at a cost of billions of dollars. The evaluation of models of volcanic column is notoriously challenging owing to difficulties to gather independent observations of model inputs (e.g. the flux of ash and gas coming out from a crater) and outputs (e.g. the height of a volcanic column). In turn, this hinders the reliability of model predictions and volcanic risk assessment. Accordingly, the third and fourth objectives of this project were:
3 – Deliver a new, state-of-the-art database of independently estimated eruption parameters that will become a reference tool for evaluating volcanic plume models.
4 – Apply this database to conduct an observationally-constrained plume model comparison, and use enhanced models to improve the assessment of climate-volcano feedbacks related to plume rise as well as risks related to ash dispersion.
The new database is designed to become a flagship product of the international volcanology community. It will contribute to improve ash dispersion forecast and, in turn, the warnings issued by the Volcanic Ash Advisory Centers which are in charge of communicating with aviation authorities during volcanic crises.
The work performed had two core outcomes to date.

First, VOLCPRO produced the first evidence that unchecked climate change could affect the transport and chemistry of volcanic gases in the atmosphere, and in turn their ability to cool our planet. Critically, it was found that relatively large but infrequent tropical eruptions will see their cooling effect enhanced, but that relatively small and frequent tropical eruptions will see their cooling effect dampened. Th project thus opened the question of whether global warming will result in more or less volcanic cooling.

Second, VOLCPRO resulted in the production of the Independent Volcanic Eruption Source Parameter Archive (IVESPA). IVESPA is a database of volcanological observations that will provide long-term support to developp and evaluate computer models that are at the heart of volcanic hazard management worldwide. The IVESPA working group comprises 17 international members. It has been endorsed by the international volcanology association called IAVCEI and is supported by the British Geological Survey.

The results of the project have been dissiminated to the scientific communities via six scientific peer-reviewed publications with more coming. The IVESPA database is also available at http://ivespa.co.uk/. Furthermore, the project results have been dissiminated via a range of media article focusing on how climate change could affect volcanic eruptions. The press release from the Nature communications journal and the University of Cambridge (e.g. https://www.cam.ac.uk/stories/volcanoesandclimate) resulted in over 50 media articles.
The novel work performed on interactions between climate change and volcanic eruptions means that we can no longer assume that future volcanic climate effects will be similar to what we experienced in the past, a mainstream assumption in climate projections. To ensure that this assumption is reassessed in line with the project results, the researcher is actively communicating with the scientific community in charge of designing scenarios for future anthropogenic and natural gas emissions that are at the core of climate projections. Ultimately, the project will thus contribute to improve climate projections which feed assesment report of the Intergovernmental Panel on Climate Change, and in turn policies worldwide to limit climate change and mitigate its effects.

The IVESPA database is a transformative step towards leveling up the model evaluation standards of the research community working on volcanic plumes. IVESPA will directly contribute to major developments of computer models used to simulate volcanic plumes and ash dispersion in the future. This will in turn contribute to improve global volcanic hazard management capabilities, in particular those related to hazards posed by ash fallout (e.g. respiratory issues. infrastructure damage, building collapse) and the closure of airspace owing to the presence of high ash concentration in the atmosphere.
Dispersion of volcanic gas simulated in a recent (1995) and future (2095) climate.