The 2022 eruption of the Hunga Tonga-Hunga Ha’apai volcano caused an abnormal cooling of the stratosphere instead of the expected warming. The volcano erupted at the “ideal” depth of 150 meters, and the explosion sent 146 teragrams of water vapor—10% of the stratosphere’s total moisture—into the sky. The water stopped the sulfur, and started giving off heat into space, cooling down the atmosphere by 0.5–1°C in some layers. This didn’t stop the global heatwave of 2023–2024, but scientists say this “water vapor trail” will affect chemical processes in the atmosphere until the end of the 2020s.
The Daily Galaxy says that the 2022 eruption of the Hunga Tonga-Hunga Ha’apai volcano caused the stratosphere to cool down instead of warming up like it was supposed to.
The most important part of this story is the 146 teragrams of water vapor that the eruption literally “threw” into the sky. This is equal to 10% of the typical moisture content in the stratosphere.
Luis Millán, a scientist at NASA’s Jet Propulsion Laboratory, says this eruption was almost four times bigger than the famous 1991 eruption of Mount Pinatubo.
The reason for the anomaly was the depth of the eruption. The caldera was located 150 meters below the water’s surface. Researchers say this is the ideal depth: low enough for the magma to turn the ocean water into steam, but shallow enough that the water pressure won’t contain the explosion. So, the water stopped the sulfur from heating up the atmosphere, and steam rose into the sky instead.
“Water vapor radiates heat. The scientists say that it doesn’t keep it.
While sulphates from regular volcanoes act like a “blanket,” the water from Tonga started to release energy into space. Based on the info we have, this caused a drop in temperature of 0.5 to 1 degree Celsius in some layers of the atmosphere.
Professor Amanda Maycock of the University of Leeds said the eruption didn’t affect the record-breaking heatwaves of 2023 and 2024, even though scientists had been looking for a link like that for a while. At the same time, the force of the explosion was so strong that the pressure wave went around the Earth four times, and ‘meteotsunamis’ were even recorded in the Mediterranean Sea.
The study found that by the end of 2025, moisture levels in the atmosphere were still above average. Scientists say that this “water footprint” is going to keep messing with chemical processes in the atmosphere until the end of the 2020s.