(CNN) — The volcanic eruption in Tonga, one of the strongest on the planetexpelled so much water vapor into the atmosphere that it is likely to temporarily warm the Earth’s surface, according to detections by a NASA satellite.
When the Hunga Tonga-Hunga Ha’apai undersea volcano erupted on January 15, 65 kilometers north of Tonga’s capital, it triggered a tsunami and sonic boom that circled the globe, twice.
The eruption sent a large plume of water vapor into the stratosphere, which is 8 to 33 miles (12 to 53 kilometers) above Earth’s surface. It was enough water to fill 58,000 Olympic swimming pools, according to detections from a NASA satellite.
The detection was made by the Microwave Limb Sounder (MLS) instrument on NASA’s Aura satellite. The satellite measures water vapor, ozone and other atmospheric gases. After the eruption, scientists were surprised by the water vapor readings.
They calculate that the eruption contributed 146 teragrams of water to the stratosphere. A teragram is the equivalent of a trillion grams, and in this case, it was equivalent to 10% of the water already present in the stratosphere.
That’s nearly four times the amount of water vapor that reached the stratosphere following Mount Pinatubo’s 1991 eruption in the Philippines.
A new study on the water vapor results was published in July in Geophysical Research Letters.
“We’ve never seen anything like it,” study author Luis Millán, an atmospheric scientist at NASA’s Jet Propulsion Laboratory in Southern California, said in a statement. “We had to carefully inspect all the measurements on the column to make sure they were reliable.”
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The Microwave Limb Sounder instrument can measure natural microwave signals from Earth’s atmosphere and detect them even through thick ash clouds.
“The MLS was the only instrument with a dense enough coverage to capture the water vapor column at the time it was produced, and the only one that was not affected by the ash released by the volcano,” said Millán.
The Aura satellite was launched in 2004 and since then has only measured two volcanic eruptions that raised a significant amount of water vapor high into the atmosphere. But water vapor from the 2008 Kasatochi eruption in Alaska and the 2015 Calbuco eruption in Chile dissipated fairly quickly.
Normally, powerful volcanic eruptions like Mount Pinatubo or the 1883 Krakatoa eruption in Indonesia cool the Earth’s surface temperature because the gas, dust, and ash they spew reflect sunlight back into space. This “volcanic winter” occurred following the eruption of Mount Tambora in 1815, triggering “the year without summer” in 1816.
The Tonga eruption was different because the water vapor it sent into the atmosphere can trap heat, potentially causing warmer surface temperatures. According to the researchers, the excess water vapor might remain in the stratosphere for several years.
Additional water vapor in the stratosphere might also lead to chemical reactions that temporarily contribute to the depletion of Earth’s protective ozone.
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Fortunately, the heating effect of the water vapor is expected to be small and temporary, dissipating as the extra vapor dries up. The researchers don’t think it’s enough to aggravate existing conditions due to the climate crisis.
The researchers believe that the main reason for the amount of water vapor released is due to the depth of the volcano’s caldera, 150 meters below the ocean surface.
If it were too deep, the depth of the ocean would have silenced the eruption, and if it were too shallow, the amount of seawater heated by the erupting magma would not have matched what reached the stratosphere, the researchers said.
Scientists are still working to understand the unusual energetic eruption and all its superlatives, including the hurricane winds that reached space.
