Terrawatch: how climate change alters impact of volcanic eruptions

Terrawatch: how climate change alters impact of volcanic eruptions

Terrawatch: how climate change alters impact of volcanic eruptions

Cooling impact of very explosive eruptions could be amplified while moderate eruptions have less effect

A plume of ash and steam rises from the Taal volcano in Batangas province, the Philippines

Wed 6 Oct 2021 01.00 EDT

It’s well known that volcanic eruptions alter the climate but can human-made climate change alter volcanic eruptions? Curiously, the answer appears to be yes.

When the Philippine volcano Mount Pinatubo erupted in 1991, the resulting sulphuric acid haze suppressed global temperatures by 0.5C for more than a year. Very explosive eruptions like this are rare – they occur once or twice a century on average – but their cooling impact could be amplified by as much as 15% as the world becomes warmer.

That’s because the stratosphere (the second layer of the Earth’s atmosphere) will be warmer and less stratified which, according to research published in Nature Communications, will result in sulphate aerosols spreading further and faster around the world, blocking more solar radiation.

Meanwhile, moderately explosive eruptions – such as that of the Taal volcano in the Philippines in 2020 – which tend to occur once a year may have their cooling impact diminished by as much as 75% in a warmer world.

That’s because the height of the tropopause (the boundary between the first and second layers of the atmosphere) is predicted to increase, making it less likely that small and medium volcanic plumes will reach the stratosphere, and more likely that aerosols will be quickly washed out of the lower atmosphere by rain and snow.

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