NEW YORK (AP) — When an undersea volcano erupted in Tonga in January, its watery blast was huge and unusual — and scientists are still trying to understand its impacts.
The volcano, known as Hunga Tonga-Hunga Ha’apai, shot millions of tons of water vapor high up into the atmosphere, according to a study published Thursday in the journal Science.
The researchers estimate the eruption raised the amount of water in the stratosphere — the second layer of the atmosphere, above the range where humans live and breathe — by around 5%.
Now, scientists are trying to figure out how all that water could affect the atmosphere, and whether it might warm Earth’s surface over the next few years.
“This was a once-in-a-lifetime event,” said lead author Holger Voemel, a scientist at the National Center for Atmospheric Research in Colorado.
Big eruptions usually cool the planet. Most volcanoes send up large amounts of sulfur, which blocks the sun’s rays, explained Matthew Toohey, a climate researcher at the University of Saskatchewan who was not involved in the study.
The Tongan blast was much soggier: The eruption started under the ocean, so it shot up a plume with much more water than usual. And since water vapor acts as a heat-trapping greenhouse gas, the eruption will probably raise temperatures instead of lowering them, Toohey said.
It’s unclear just how much warming could be in store.
Karen Rosenlof, a climate scientist at the National Oceanic and Atmospheric Administration who was not involved with the study, said she expects the effects to be minimal and temporary.
“This amount of increase might warm the surface a small amount for a short amount of time,” Rosenlof said in an email.
The water vapor will stick around the upper…