Despite the known ability of volcanic eruptions to lower global temperatures, the recent eruption of the Hunga-Tonga volcano was not large enough to have a meaningful impact on them and climate change.
This weekend, the Hunga-Tonga-Hunga-Ha’apai volcano made headlines after erupting and sending an enormous cloud of ash into the air.
The eruption also caused a tsunami that hit most of the countries located in the Pacific Rim.
And while the full scale of the damage is only gradually becoming known, early data has allowed scientists to conclude that there will hardly be any real impact on climate change.
The mechanism through which volcanoes can affect temperatures on the planet has long been studied and is now better understood by scientists.
How volcanoes can have an impact on climate
Volcanic eruptions release massive quantities of sulfur dioxide (SO2) into the atmosphere, which is a compound with sunlight-reflecting and scattering properties.
Hence, a large enough concentration of sulfate aerosols in the air can reflect enough light away from earth to actually result in cooler temperatures.
A leading example of this occurred in 1991 during the eruption of Mount Pinatubo in the Philippines, which resulted in the release of somewhere between 6 and 22 million metric tons of SO2 over the course of three days.
That is the equivalent of roughly 20% of man-made sulfur dioxide emissions in 2021.
Volcanic SO2 is flung many miles up into the stratosphere, well above most clouds and is not as affected by weather conditions. Hence, it can stay there longer and is only removed very slowly over time, largely thanks to gravity.
In fact, it may take months or even years for the SO2 to be brought back down to earth.
Thus, as a result of the massive release of sulfate aerosols, the https://pubs.usgs.gov/fs/1997/fs113-97/Pinatubo eruption caused global temperatures to drop almost an entire degree Fahrenheit throughout the year that followed the eruption.
It is not likely that we will have the same luck with Hunga-Tonga, however.
Early satellite imagery suggests that the SO2 released from this recent eruption is only 1-2% the amount released in 1991 by Piantubo.