Undersea volcano eruption in Tonga was a "once-in-a-lifetime event" that could warm Earth's surface, scientists say

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, which dwarfed the power of the Hiroshima atomic bomb, 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%.