The eruption of a submarine volcano in the Pacific Ocean in January was so large that it triggered a global shock wave. There is. said on Thursday.
Researchers estimate that the injection of at least 55 million tons of water vapor into the stratosphere could temporarily further deplete the atmosphere’s protective ozone layer.
The eruption of the Hunga Tonga-Hunga Ha’apai volcano in the island nation of Tonga on January 15 largest in decadesIt not only caused a tsunami that devastated parts of Tonga, but also small tsunamis thousands of miles away caused by changes in air pressure as the shock wave circled the world.
Because it occurred about 500 feet underwater, the eruption of superheated lava explosively turned seawater into steam. A plume of water vapor, volcanic gases, and ash reached an altitude of 35 miles. This increased the amount of water vapor in the stratosphere ending at an altitude of 31 miles by at least 5%.
“This is absolutely unique, because we were able to measure water vapor in the stratosphere,” said Holger Fommel, senior scientist at the National Center for Atmospheric Research in Boulder, Colorado. started before.“ Dr. Vömel is the lead author of the paper on the findings. Published in Science magazine.
Like carbon dioxide and other greenhouse gases, water vapor absorbs and re-emits heat in the form of infrared radiation from the Earth’s surface. Therefore, adding large amounts of water vapor is expected to increase warming for several years until the gas dissipates.
Large eruptions of land-based volcanoes do not release much water vapor, but can inject large amounts of sulfur dioxide gas into the stratosphere, which provides a short-term cooling effect. After the 1991 eruption of Mount Pinatubo in the Philippines, the average global temperature fell by 1 degree Fahrenheit (0.6 degrees Celsius) for more than a year.
Dr Former said estimates of the amount of additional warming the Tonga eruption would add are very speculative at this point. The additional warming is likely to last longer than the post-Pinatubo cooling, he added.
Susan Solomon, an atmospheric scientist at the Massachusetts Institute of Technology whose 2010 study described the effects of changes in stratospheric water vapor on temperature, said the Tonga eruption “will add about 0.05 degrees of warming to the global average temperature. It is possible,” he said. Probably 3 to 5 years.
“This is a lower number than would be expected from carbon dioxide nearing 0.1 to 0.2 degrees per decade,” she said. Dr. Solomon was not involved in the Tonga research.
All that water vapor can very likely change atmospheric chemistry that destroys ozone, the oxygen molecule that protects life on Earth from harmful ultraviolet radiation from the sun.
“By significantly increasing the amount of water vapor, the amount of ozone should decrease,” says Dr. Vömel. But it will be temporary, he said, because ozone production and destruction is a “continuous cycle.”
Dr. Solomon said that the loss of ozone near the stratospheric-lower atmospheric boundary would very likely cause some cooling of the Earth’s surface, offsetting the warming from the added water vapor.
published research The amount of water vapor released by Tonga’s eruption was estimated to be about 160 million tonnes in July, nearly tripling.
The study used data from NASA satellites. NASA satellites provide daily water vapor measurements around the world. Dr. Vömel and his colleagues took a different approach, using data from instruments in small packages called radiosondes that are carried aloft in balloons. Radiosondes are launched periodically, usually he every 12 hours, at weather stations around the world.
This approach was made possible because there were regular balloon launches from Australia, Fiji and elsewhere close enough to the eruption to bring instruments into the volcanic plume. It also helped that the water vapor concentration in the plume was very high.
“Any self-respecting scientist who knows stratospheric water vapor knows that you can’t measure it with a radiosonde,” Dr. Vömel said. “Don’t even think about it. But this event was incredibly huge.”
His team’s estimate of 55 million tonnes was conservative, and their calculations indicated that the amount could be double that. That’s still lower than in previous studies, but the difference in impact “probably isn’t that big,” he said.
“It’s just a scientific discourse,” he said of the difference in estimates between the two studies. “Once all the dust has settled, we will have a better understanding at some point.”