The unprecedented amount of water vapor hurled into the atmosphere, as detected by NASA’s Microwave Limb Sounder, could end up warming Earth’s surface temporarily.
On January 15, 2022, the Hunga Tonga-Hunga Ha’apai volcano erupted, setting off a sonic boom that circled the globe twice and unleashing a tsunami racing around the world. The underwater eruption in the South Pacific Ocean also blasted a massive plume of water vapor into Earth’s stratosphere. In fact, the unprecedented amount of water vapor was so enormous, that it was enough to fill more than 58,000 Olympic-size swimming pools. The sheer volume of water vapor could be enough to temporarily affect Earth’s global average temperature.
“We’ve never seen anything like it,” said Luis Millán, an atmospheric scientist at NASA’s Jet Propulsion Laboratory in Southern California. He led a recent investigation examining the amount of water vapor that the Tonga volcano injected into the stratosphere, the layer of the atmosphere between about 8 and 33 miles (12 and 53 kilometers) above Earth’s surface.
Published in Geophysical Research Letters, the study by Millán and his colleagues estimates that the Tonga eruption sent an incredible 146 teragrams (1 teragram equals a trillion grams) of water vapor into Earth’s stratosphere. That’s an amount equal to 10% of the water already present in that atmospheric layer. That’s nearly four times the amount of water vapor that scientists estimate the 1991 Mount Pinatubo eruption in the Philippines lofted into the stratosphere.
“We’ve never seen anything like it.” — Luis Millán
Millán analyzed data from the Microwave Limb Sounder (MLS) instrument on NASA’s Aura satellite, which measures atmospheric gases, including water vapor and ozone. After the Tonga volcano erupted, the MLS team started seeing water vapor readings that were off the charts. “We had to carefully inspect all the measurements in the plume to make sure they were trustworthy,” said Millán.
A Lasting Impression
Volcanic eruptions rarely inject much water into the stratosphere. In the 18 years that NASA has been taking measurements, only two other eruptions – the 2008 Kasatochi event in Alaska and the 2015 Calbuco eruption in Chile – sent appreciable amounts of water vapor to such high altitudes. But those were mere blips compared to the Tonga event, and the water vapor from both previous eruptions dissipated quickly. The excess water vapor injected by the Tonga volcano, on the other hand, could remain in the stratosphere for several years.
This extra water vapor could influence atmospheric chemistry, boosting certain chemical reactions that could temporarily worsen the depletion of the ozone layer. It could also influence surface temperatures. Massive volcanic eruptions like Krakatoa and Mount Pinatubo typically cool Earth’s surface by ejecting gases, dust, and ash that reflect sunlight back into space. In contrast, the Tonga volcano didn’t inject large amounts of aerosols into the stratosphere, and the huge amounts of water vapor from the eruption may have a small, temporary warming effect, since water vapor traps heat. The effect would dissipate when the extra water vapor cycles out of the stratosphere and would not be enough to noticeably exacerbate climate change effects.
The sheer amount of water injected into the stratosphere was likely only possible because the underwater volcano’s caldera – a basin-shaped depression usually formed after magma erupts or drains from a shallow chamber beneath the volcano – was at just the right depth in the ocean: about 490 feet (150 meters) down. Any shallower, and there wouldn’t have been enough seawater superheated by the erupting magma to account for the stratospheric water vapor values Millán and his colleagues saw. Any deeper, and the immense pressures in the ocean’s depths could have muted the eruption.
The MLS instrument was well situated to detect this water vapor plume because it observes natural microwave signals emitted from Earth’s atmosphere. Measuring these signals enables MLS to “see” through obstacles like ash clouds that can blind other instruments measuring water vapor in the stratosphere. “MLS was the only instrument with dense enough coverage to capture the water vapor plume as it happened, and the only one that wasn’t affected by the ash that the volcano released,” said Millán.
Reference: “The Hunga Tonga-Hunga Ha’apai Hydration of the Stratosphere” by L. Millán, M. L. Santee, A. Lambert, N. J. Livesey, F. Werner, M. J. Schwartz, H. C. Pumphrey, G. L. Manney, Y. Wang, H. Su, L. Wu, W. G. Read and L. Froidevaux, 1 July 2022, Geophysical Research Letters.
The MLS instrument was designed and built by JPL, which is managed for NASA by Caltech in Pasadena. NASA’s Goddard Space Flight Center manages the Aura mission.
“58,000 Olympic-Size Swimming Pools” Well, it is very modern to use that kind of measurement, but it is beyond stupid, as almost no ordenairy ppl know how much water goes into a swimmingpool. You can do better.
I was thinking the same thing. This metric does not provide any good context. Neither does “146 teragrams”. “146 Million metric tons” would be a much better choice.
Soren Bro- most “ordenairy ppl” are at least somewhat aware of the scale of an Olympic sized swimming pool. Perhaps you should have your own affairs in order before you deem something “beyond stupid”. You can do better.
However, do ordinary people know how many Olympic sized pools could be filled by the water vapor typically in the atmosphere? That 58,000 OSSPs-equivalence only has meaning in the context of the proportional increase in absolute humidity. They mention that the increase was about 10% of the typical amount of water vapor. Big numbers might impress the innumerate; however,the percentage is the only number that has any significance in this situation because nobody is going to extract the water and use it to fill swimming pools.
I agree with Soren Bro. I don’t understand the compulsion shown by some people for converting legitimate measurements or estimates to some other non-standard units, especially when the more important number is a percentage change.
I disagree. Most people don’t have the money to live a life where they have regular experience with Olympic size swimming pools. As such, I bet most people think of a neighbor’s swimming pool if the pool is big enough for swimming. This nutty metric of Olympic size swimming pools is normally useless. It is useless to pretty much cite any reference that is multiple decades in scale difference from the phenomena it is compared. You might as well cite the amount of water as 0.75 liter soda bottles. Neither that nor the pools is something we can conceptualize when we try to multiply by tens of thousands. There is just faith in math at that point, so the reference has no point.
I’ve been morbidly curious about the mass loss of sea life that must have occurred. With the size of the caldera, there had to have been massive amounts of fish, whales, etc. that were instantly boiled and sent miles into the air.
I like the Olympic swimming pools metric. Though, it might be more useful to compare it with the moisture in a hurricane.
Olympic swimming pools all have standard lengths. Do they all have the same widths and bottom contours? If not, then they have different volumes. That is, the number of pools that could be filled by the added Tonga water vapor is not constant. Why would you advocate for a ‘standard’ of comparison that you can’t even visually compare?