Explosive eruptions can cause substantial cooling of global surface temperatures, lasting for anywhere between 1 to 10 years. We have known about this cooling for centuries, with our temperature records often showing distinct dips following major eruptions.
One of the clearest examples of this was the 1815 eruption of Mount Tambora, an explosive event that caused a 1°C drop in global land temperatures. The eruption was so energetic that volcanic gases were injected into the stratosphere, the layer of the atmosphere 10 to 50km above the surface. This caused incoming sunlight to be blocked, meaning that not as much reached the Earth’s surface.
While more explosive volcanoes tend to cause more global cooling, it’s not always the case. It depends on the ejected gases reaching the stratosphere, and on wind systems. Mount St Helens, one of the most violent eruptions of modern time, hardly made a dent in global temperatures due to its gases not persisting in the stratosphere.
Could volcanic eruptions mitigate the increased temperatures from climate change? Unfortunately not. Volcanic eruptions have occurred over history and are a natural component of our atmosphere. Their effect is also short-lived, with surface cooling from eruptions lasting a matter of years, while surface warming from excessive carbon dioxide emissions lasts for thousands.
Asked by: David Scott, Port St Mary, Isle of Man
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