The huge amount of water vapor hurled into the atmosphere, as detected by NASA\u2019s Microwave Limb Sounder, could end up temporarily warming Earth\u2019s surface.<\/p>\n<\/div>\n<\/div>\n
When the Hunga Tonga-Hunga Ha\u2019apai volcano\u00a0erupted<\/a>\u00a0on Jan. 15, it sent a tsunami racing around the world and set off a sonic boom that circled the globe twice. The underwater eruption in the South Pacific Ocean also blasted an enormous plume of water vapor into Earth\u2019s stratosphere \u2013 enough to fill more than 58,000 Olympic-size swimming pools. The sheer amount of water vapor could be enough to temporarily affect Earth\u2019s global average temperature.<\/p>\n \u201cWe\u2019ve never seen anything like it,\u201d said Luis Mill\u00e1n, an atmospheric scientist at NASA\u2019s Jet Propulsion Laboratory in Southern California. He led a new study 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\u2019s surface.<\/p>\n<\/div>\n<\/div>\n<\/div>\n In the\u00a0study<\/a>, published in Geophysical Research Letters, Mill\u00e1n and his colleagues estimate that the Tonga eruption sent around 146 teragrams (1 teragram equals a trillion grams) of water vapor into Earth\u2019s stratosphere \u2013 equal to 10% of the water already present in that atmospheric layer. That\u2019s nearly four times the amount of water vapor that scientists estimate the 1991\u00a0Mount Pinatubo eruption<\/a>\u00a0in the Philippines lofted into the stratosphere.<\/p>\n Mill\u00e1n analyzed data from the\u00a0Microwave Limb Sounder<\/a>\u00a0(MLS) instrument on NASA\u2019s\u00a0Aura<\/a>\u00a0satellite, 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. \u201cWe had to carefully inspect all the measurements in the plume to make sure they were trustworthy,\u201d said Mill\u00e1n.<\/p>\n<\/div>\n<\/div>\n<\/div>\n A Lasting Impression<\/b><\/p>\n Volcanic eruptions rarely inject much water into the stratosphere. In the 18 years that NASA has been taking measurements, only two other eruptions \u2013 the 2008\u00a0Kasatochi event<\/a>\u00a0in Alaska and the 2015\u00a0Calbuco eruption<\/a>\u00a0in Chile \u2013 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.<\/p>\n This extra water vapor could influence atmospheric chemistry, boosting certain chemical reactions that could temporarily worsen depletion of the ozone layer. It could also influence surface temperatures. Massive volcanic eruptions like Krakatoa and Mount Pinatubo typically cool Earth\u2019s surface by ejecting gases, dust, and ash that reflect sunlight back into space. In contrast, the Tonga volcano didn\u2019t 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.<\/p>\n The sheer amount of water injected into the stratosphere was likely only possible because the underwater volcano\u2019s caldera \u2013 a basin-shaped depression usually formed after magma erupts or drains from a shallow chamber beneath the volcano \u2013 was at just the right depth in the ocean: about 490 feet (150 meters) down. Any shallower, and there wouldn\u2019t have been enough seawater superheated by the erupting magma to account for the stratospheric water vapor values Mill\u00e1n and his colleagues saw. Any deeper, and the immense pressures in the ocean\u2019s depths could have muted the eruption.<\/p>\n<\/div>\n<\/div>\n<\/div>\n The MLS instrument was well situated to detect this water vapor plume because it observes natural microwave signals emitted from Earth\u2019s atmosphere. Measuring these signals enables MLS to \u201csee\u201d through obstacles like ash clouds that can blind other instruments measuring water vapor in the stratosphere. \u201cMLS was the only instrument with dense enough coverage to capture the water vapor plume as it happened, and the only one that wasn\u2019t affected by the ash that the volcano released,\u201d said Mill\u00e1n.<\/p>\n The MLS instrument was designed and built by JPL, which is managed for NASA by Caltech in Pasadena. NASA\u2019s Goddard Space Flight Center manages the Aura mission.<\/p>\n![\"Hunga](\"https:\/\/d2pn8kiwq2w21t.cloudfront.net\/images\/e1-Tonga_pre_eruption.width-1024.jpg\")
<\/div>\n<\/div>\n<\/div>\nThis satellite image shows an intact Hunga Tonga-Hunga Ha\u2019apai in April 2015, years before an explosive underwater volcanic eruption obliterated most of the Polynesian island in January 2022.<\/h5>\n<\/div>\n
\u00a0Credit: NASA Earth Observatory image by Jesse Allen, using Landsat data from the U.S. Geological Survey<\/span><\/h5>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
![\"Hunga](\"https:\/\/d2pn8kiwq2w21t.cloudfront.net\/images\/e2-Tonga_ash_plume.width-1024.jpg\")
<\/div>\n<\/div>\n<\/div>\nAn image from Jan. 16, 2022, shows the ash plume from the Hunga Tonga-Hunga Ha\u2019apai volcanic eruption that occurred the day before. An astronaut took a photograph of the plume from the International Space Station.<\/h5>\n<\/div>\n
\u00a0Credit: NASA<\/span><\/h5>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n