On 15 January 2022, the underwater volcano Hunga Tonga–Hunga Ha’apai erupted, unleashing a powerful tsunami that destroyed homes and caused four deaths throughout Tonga.
Another lasting effect of this event — the largest underwater explosion ever recorded by modern scientific instruments — was the huge amount of aerosol and water vapor plumes it launched skyward.
examined how Hunga’s eruption affected climate in the Southern Hemisphere over the following 2 years.
They found that in the year following the eruption, the cooling effect from the volcanic aerosols reflecting sunlight into outer space was stronger than the warming caused by water vapors trapping heat in the atmosphere.
The researchers used satellite data to examine how stratospheric aerosols, gases, and temperatures changed after the eruption.
The Hunga eruption contributed about 150 metric megatons of water vapor into the stratosphere — an amount so high that it raised global levels of stratospheric water vapor by about 10%.
This massive water injection cooled temperatures in the tropical stratosphere by 4°C in March and April of 2022.
The Hunga eruption also released between 0.5 and 1.5 metric megatons of sulfur dioxide into the stratosphere.
The Hunga aerosol load was not very large, and its effects were mostly confined to the Southern Hemisphere in 2022 and 2023.
This brief change means that Hunga’s eruption may have caused slight cooling in the Southern Hemisphere, but the researchers say it would be challenging to glean that same information from meteorological observations alone.
The submerged volcano Hunga Tonga–Hunga Ha’apai erupted on January 15, 2022, causing a devastating tsunami that devastated homes and claimed four lives across Tonga. Massive amounts of aerosol and water vapor plumes were launched skyward, making this event—the largest underwater explosion ever captured by contemporary scientific instruments—a long-lasting impact.
Schoeberl & Associates. studied the effects of Hunga’s eruption on the Southern Hemisphere’s climate during the next two years. They discovered that in the year that followed the eruption, the warming brought on by water vapors trapping heat in the atmosphere was less powerful than the cooling effect from volcanic aerosols reflecting sunlight into space. At the end of 2023, however, the majority of the volcano’s effects had subsided.
The researchers examined changes in temperatures, gases, and aerosols in the stratosphere following the eruption using data from satellites. About 150 metric megatons of water vapor were released into the stratosphere by the Hunga eruption; this was an amount that increased the global concentration of stratospheric water vapor by roughly 10%. In March and April of 2022, the tropical stratosphere experienced a 4°C drop in temperature as a result of this massive water injection. As a result of this brief cooling, a secondary circulation pattern was established, which decreased ozone levels throughout 2022.
A further release of sulfur dioxide into the stratosphere from the Hunga eruption was between 0 and 1 metric megatons. The difference between incoming and outgoing radiation can be reduced by sulfur dioxide by producing sulfate aerosols, which reflect sunlight. When Mount Pinatubo erupted in 1991 and released roughly 20 metric megatons of sulfur dioxide, the aerosol load was so high that it caused a global cooling. The effects of the Hunga aerosol load in 2022 and 2023 were primarily limited to the Southern Hemisphere due to its small size.
During the two years before it returned to preeruption levels, there was a very slight global decrease in radiative flux, less than 0 point25 watt per square meter, despite the eruption having a brief impact on Earth’s radiative balance. Over the course of a year, the Earth’s surface, oceans, and atmosphere collectively absorb roughly 240 watts of solar power per square meter. It would be difficult to infer the same information from meteorological observations alone, the researchers say, but this brief shift suggests that Hunga’s eruption may have caused a slight cooling in the Southern Hemisphere. (Journal of Geophysical Research: Atmospheres, 2024; doi: 10.1029/2024JD041296).
