Working with a colleague from the University of Edinburgh, a team of researchers at the California Institute of Technology’s Jet Propulsion Laboratory discovered evidence that the Hunga Tonga-HungaHa’apai eruption earlier this year may have pushed so much water into the atmosphere that it may have weakened the Earth’s ozone layer. The group studied data from satellites to measure how much water was launched into the atmosphere in their paper published in the journal Geophysical Research Letters, and they believe it could lead to ozone layer depletion.
The Tonga eruption occurred on and beneath the seafloor in the Pacific Ocean near Tonga on January 15. The blast blew massive amounts of ocean water skyward, high enough that much of it made it into the stratosphere, in addition to spewing a variety of gases into the ocean, some of which eventually made their way into the atmosphere. Water at such heights, according to the researchers, could be present for many years, if not decades.
The work entailed gathering data from satellites equipped with sensors that had captured the eruption. The researchers discovered measurements of released sulphur dioxide in addition to dramatic video imagery. When they compared it to other eruptions, they discovered that the amount was not unusual. When they measured how much water was blown into the atmosphere, they discovered something unexpected: it was more than had ever been measured before, and it was blown higher than had ever been observed before—some of it into the mesosphere.
According to their calculations, the total amount of water that made its way into the stratosphere was approximately 146 Tg. In other words, they believe that seawater from the eruption increased the total amount of water in the stratosphere by about 10%.
While the sulphur emitted into the atmosphere may have a minor cooling effect on the planet, the water will have a warming effect because water absorbs solar energy. They also point out that when water molecules combine with oxygen atoms, hydroxide is formed, which could lead to ozone depletion.