Water blown from Tonga’s underwater volcano could weaken ozone layer, scientists warn

TongaJanuary’s volcanic eruption blew out enough water to fill more than 58,000 Olympic swimming pools – and could weaken the ozone layer.

Scientists who have examined the amount of water vapor ejected by the Hunga Tonga-Hunga Ha’apai volcano have described it as “unprecedented”.

The powerful steam formed when seawater from the South Pacific came into contact with lava and was “superheated”.

The eruption created sound waves heard up to Alaska 6,200 miles away, in a sonic boom that circled the globe twice.

In a new study, experts from NASA’s Jet Propulsion Laboratory predict that the volume of water could be enough to temporarily affect the global average temperature.

It could also temporarily stimulate chemical reactions in the atmosphere that worsen ozone depletion.

“We’ve never seen anything like it,” said atmospheric scientist Dr. Luis Millán.

In the study published in Geophysical Research LettersDr. Millán and his colleagues estimate that the Tonga eruption sent about 146 million tons of water vapor into the stratosphere.

The stratosphere is the layer of the atmosphere between about 8 and 33 miles (12 and 53 kilometers) above the Earth’s surface.

The water from the January 15 eruption is about 10% of the water content already in the stratosphere.

Comparable amounts of water have only been blown at such high altitudes by volcanoes twice before in the 18 years NASA has taken measurements.

These were the 2008 Kasatochi event in Alaska and the 2015 Calbuco eruption in Chile.

The water from these events quickly dissipated, but NASA researchers say liquid from the Tonga volcano could linger in the stratosphere for up to ten years.

To determine the volume of water vapor, scientists analyzed data from the Microwave Limb Sounder (MLS) instrument on NASA’s Aura satellite.

This measures atmospheric gases, including water vapor and ozone, by observing the natural microwave signals emitted by the Earth’s atmosphere.

The researchers noticed that the readings increased significantly after the Tonga volcano erupted.

Dr Millán, who operates the instrument from Pasadena, California, USA, said: ‘We had to carefully inspect all the measurements in the plume to make sure they were trustworthy.

“MLS was the only instrument with dense enough coverage to capture the water vapor plume as it occurred, and the only one that was unaffected by the ash released from the volcano.”

When water molecules break down in the stratosphere, they release reactive hydrogen oxide molecules.

These react with ozone and destroy it on their own, but also convert chlorine-containing gases into other destructive molecules.

Water vapor also traps heat, so the eruption could cause a temporary warming effect on Earth’s surface, for what researchers believe is the first time.

Although considered a “greenhouse gas”, like carbon dioxide and methane, not all warming would be enough to exacerbate the effects of climate change.

This is because the heat would dissipate as the extra water was naturally removed from the stratosphere.

Conversely, previous massive volcanic eruptions, such as Krakatoa, threw ash, dust, and gases into the atmosphere that reflected sunlight back into space and produced a cooling effect.

In the article, Dr Millán wrote: “Continued monitoring of volcanic gases from this and future eruptions is essential to better quantify their different roles in climate.”

Researchers believe that the Tonga volcano was only able to produce the large amounts of water vapor due to its precise underwater depth.

Its caldera – the large crater formed when magma begins to erupt – is thought to be around 150 meters (490 ft) below.

If it had been shallower, there wouldn’t have been enough magma-superheated seawater to account for the volume of stratospheric water vapour.

However, deeper and ocean pressure could have dampened the violent eruption.