Massive undersea eruption filled the atmosphere with water |  Science

Massive undersea eruption filled the atmosphere with water | Science

On January 15, the Hunga Tonga-Hunga Ha’apai volcano in Tonga erupted under the sea, shaking the South Pacific nation and sending tsunamis raging around the world. The outbreak was that most powerful ever recorded, causing an atmospheric shock wave that circled the globe four times, sending a plume of debris more than 50 kilometers into the atmosphere. But it didn’t stop there.

The ash and gases that hit the sky also shot billions of kilograms of water into the atmosphere, concludes a new study. That water is likely to remain there for years, where it can eat away at the ozone layer and perhaps even warm the Earth.

“The idea that an eruption could directly inject a large amount of water vapor into the stratosphere has not, to my knowledge, been observed directly, at least not on this scale,” says Matthew Toohey, a physicist who focuses on climate modeling and the effects of volcanic eruptions at University of Saskatchewan and was not involved in the work. “We are really surprised by this outbreak in many different ways.”

The study comes thanks to the Microwave Limb Sounder (MLS) aboard NASA’s Aura satellite. The instrument, which became operational in 2004, measures a number of compounds in the Earth’s atmosphere at altitudes of up to around 100 kilometers. Of particular interest to scientists at NASA’s Jet Propulsion Laboratory, including study co-author and JPL atmospheric scientist Luis Millán, were the water and sulfur dioxide released by the eruption, because these compounds can affect the climate. With repeated observations from the MLS both on the day of the eruption and in the days afterward, scientists were able to see the cloud, and its water content, grow and spread across the globe.

Total, the cloud shot approximately 146 billion kilograms of water into the Earth’s stratospherea dry layer of the atmosphere that begins several miles above sea level, the authors report this month in Geophysical Research Letters. That’s the equivalent of about 58,000 Olympic-sized swimming pools, or about 10% of the entire water content of the stratosphere, says Millán.

Other volcanoes have added measurable amounts of water vapor to the Earth’s atmosphere, he says, but the scale this time was unprecedented. It is probably due to the eruption’s scale and underwater location, he says. The water will probably remain in the stratosphere for half a decade or more, he says.

Large volcanic eruptions often cool the climate, because the sulfur dioxide they release forms compounds that reflect incoming sunlight. But with so much water vapor thrown up, the Tonga eruption could have a different impact. Water absorbs incoming energy from the sun, making it a powerful greenhouse gas. And the sulfur dioxide will disappear in just a few years, while the water will probably last at least 5 years – and potentially longer, Millán believes.

NASA Earth Observatory/Joshua Stevens and Lauren Dauphin

It can make the Earth warmer for years and accelerate warming from greenhouse gases, says Toohey. “We kind of just want to jump ahead a few years.”

But the actual effects on climate will likely take time to understand, said Allegra LeGrande, a physical scientist at NASA’s Goddard Institute for Space Studies who was not involved in the work. “I don’t think there’s a consensus on what the overall effect will be.”

High above Earth, the water is likely to react with other chemicals, potentially depleting the ozone layer that protects us from ultraviolet light, and even changing the circulation of air currents that control weather patterns.

As the climate impacts unfold, scientists eagerly await even more new insights from a volcanic eruption that has proven unlike any they’ve seen. “It’s exciting to see these new measurements,” says LeGrande. – It’s exciting to see something we haven’t seen before.

Leave a Reply

Your email address will not be published.