The eruption of the Tonga volcano was unusual, it could even heat the Earth

The eruption of the Tonga volcano was unusual, it could even heat the Earth

NEW YORK (AP) — When an undersea volcano erupted off Tonga in January, its blast of water was huge and unusual — and scientists are still trying to understand its effects.

The volcano, known as Hunga Tonga-Hunga Ha’apai, spewed millions of tons of water vapor high into the atmosphere, according to a study published Thursday in the journal Science.

Researchers estimate that the eruption increased the amount of water in the stratosphere – the second layer of the atmosphere, above the area where people live and breathe – by about 5%.

Now, scientists are trying to figure out how all that water could affect the atmosphere and whether it could warm the Earth’s surface in the coming 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.

Large eruptions usually cool the planet. Most volcanoes emit large amounts of sulfur, which blocks the sun’s rays, explained Matthew Tohei, a climate researcher at the University of Saskatchewan who was not involved in the study.

Tonga’s eruption was much wetter: The eruption started under the ocean, so a plume of much more water than usual was thrown up. And since water vapor acts as a heat-trapping greenhouse gas, the eruption would likely raise temperatures rather than lower them, Toohey said.

It is not clear how much heating it can store.

Karen Rosenloff, a climatologist at the National Oceanic and Atmospheric Administration who was not involved in the study, said she expects the effects to be small and temporary.

“This amount of increase can warm the surface a small amount for a short period of time,” Rosenlof said in an email.

Water vapor will hang around the upper atmosphere for a few years before entering the lower atmosphere, Toohey said. Meanwhile, the extra water may also accelerate the loss of ozone in the atmosphere, Rosenlof added.

But it’s hard for scientists to say for sure, because they’ve never seen an explosion like this.

The stratosphere extends from about 7.5 miles to 31 miles (12 km to 50 km) above Earth and is usually very dry, Voemel explained.

Voemel’s team estimated the volcano’s plume using a network of instruments suspended from weather balloons. Typically, these instruments can’t even measure water levels in the stratosphere because the amounts are so low, Voemel said.

Another research team monitored the explosion using an instrument on a NASA satellite. In their study, published earlier this summer, they estimated that the eruption was even larger, adding about 150 million metric tons of water vapor to the stratosphere — three times more than Voemel’s study found.

Voemel acknowledged that the satellite imaging may have seen parts of the plume that the balloon’s instruments could not pick up, making his estimate higher.

Either way, he said, the Tonga eruption was unlike anything seen in recent history, and studying its aftermath may hold new insights into our atmosphere.


The Associated Press Health and Science Section is supported by the Howard Hughes Medical Institute Science Education Division. AP is solely responsible for all content.

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