The eruption of the Hunga Tonga-Hunga Ha’apai underwater volcano on January 15, 2022, wasn’t just a devastating event causing tsunamis and destruction. It also sent a massive plume of aerosols and water vapor into the atmosphere, altering the Southern Hemisphere’s climate for two years.
Scientists have now analyzed the eruption’s impact using satellite data, uncovering its complex effects on Earth’s atmospheric composition and temperatures.
The eruption injected an unprecedented amount of water vapor – around 150 metric megatons – into the stratosphere, temporarily raising global stratospheric water vapor levels by 10%. This massive injection led to a significant cooling effect in the tropical stratosphere, dropping temperatures by 4°C in March and April of 2022. This cooling, in turn, triggered a secondary atmospheric circulation pattern, resulting in reduced ozone levels throughout 2022.
Along with water vapor, the eruption also released substantial amounts of sulfur dioxide – between 0.5 and 1.5 metric megatons – into the stratosphere. This sulfur dioxide converted into sulfate aerosols, which reflect sunlight and can lead to a decrease in surface radiative forcing, potentially causing global cooling. However, the Hunga eruption’s sulfur dioxide release was relatively small compared to events like the 1991 Mount Pinatubo eruption, which released 20 metric megatons of sulfur dioxide. Consequently, the cooling impact from the Hunga eruption was primarily confined to the Southern Hemisphere and was not as pronounced as in the case of Mount Pinatubo.
While the eruption did briefly affect Earth’s radiative balance, the change was minor – a global decrease in radiative flux of less than 0.25 watts per square meter over the two-year period. This slight cooling effect in the Southern Hemisphere, though measurable, would be challenging to discern solely from meteorological observations.
The Hunga Tonga-Hunga Ha’apai eruption serves as a stark reminder of the intricate connection between volcanic activity and Earth’s climate system. Even though the eruption’s impact on global climate was relatively minor, it highlights the potential for volcanic eruptions to cause significant changes in atmospheric composition and temperatures, influencing weather patterns and global radiative balance.
