Tonga volcano blast was unusual could even warm the Earth
Tongavolcano blast was unusual, could even warm the Earth
When anundersea volcano erupted in Tonga in January, its watery blast was huge andunusual — 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 highup into the atmosphere, according to a study published Thursday in the journalScience. The researchers estimate the eruption raised the amount of water inthe stratosphere — the second layer of the atmosphere, above the range wherehumans live and breathe — by around 5%.
Now,scientists are trying to figure out how all that water could affect theatmosphere, and whether it might warm Earth’s surface over the next few years. “Thiswas a once-in-a-lifetime event,” said lead author Holger Voemel, ascientist at the National Center for Atmospheric Research in Colorado.
Bigeruptions usually cool the planet. Most volcanoes send up large amounts ofsulfur, which blocks the sun’s rays, explained Matthew Toohey, a climateresearcher at the University of Saskatchewan who was not involved in the study.
TheTongan blast was much soggier: The eruption started under the ocean, so it shot up a plumewith much more water than usual. And since water vapor acts as a heat-trappinggreenhouse gas, the eruption will probably raise temperatures instead oflowering them, Toohey said.
The watervapor will stick around the upper atmosphere for a few years before making itsway into the lower atmosphere, Toohey said. In the meantime, the extra watermight also speed up ozone loss in the atmosphere, Rosenlof added.
But it’shard for scientists to say for sure, because they’ve never seen an eruptionlike this one.The stratosphere stretches from around 7.5 miles to 31 miles (12km to 50 km) above Earth and is usually very dry, Voemel explained.
Voemel’steam estimated the volcano’s plume using a network of instruments suspendedfrom weather balloons. Usually, these tools can’t even measure water levels inthe stratosphere because the amounts are so low, Voemel said.
Anotherresearch group monitored the blast using an instrument on a NASA satellite. Intheir study, published earlier this summer, they estimated the eruption to beeven bigger, adding around 150 million metric tons of water vapor to thestratosphere — three times as much as Voemel’s study found.
Voemelacknowledged that the satellite imaging might have observed parts of the plumethat the balloon instruments couldn’t catch, making its estimate higher.Eitherway, he said, the Tongan blast was unlike anything seen in recent history, andstudying its aftermath may hold new insights into our atmosphere.