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Cambridge University Science Magazine

Volcanic eruptions have long captured human imagination as explosive transient phenomena. Yet, large eruptions can affect surface temperatures across the globe for over a year, by influencing the composition of the Earth’s atmosphere.

Eruptions spew great volumes of volcanic material such as ash and gaseous matter into the atmosphere. Depending on the magnitude of the eruption, haze created by them reduces the amount of sunlight reaching the Earth’s surface on local or global scales. This can ultimately lead to a temporary cooling effect of as much as 0.5°C, lasting one or even several years. To put this in context, anthropogenic activities have resulted in a rise of a little over 1°C in global temperature since 1880.

New work from researchers in the Departments of Geography and Chemistry at the University of Cambridge suggests that our changing climate will dramatically impact the cooling effects of volcanoes. By theoretically modelling different climatic scenarios, researchers determined that, depending on the size of the explosion, the cooling effects of tropical volcanic eruptions will be differentially impacted.

For example, larger eruptions — those that cause volcanic plumes to reach higher layers of the atmosphere — were modelled to result in 15% more surface cooling as a result of climate change. This is because changes in circulation patterns and the vertical atmospheric profile result in changes to the optical properties of the plume (smaller particles) and the material rising even higher. This work highlights how climatic changes not only impact extreme weather events but can also alter effects of extreme geological phenomena on our planet.