Today’s “Planet Earth Report” –NASA Readies Plan for a ‘SuperVolcano’ Event



The relative power of an eruption is ranked on an “explosivity index,” a scale from 0 to 8 depending largely on the volume of ejected ash and gas and how high it goes — 100,000 feet or more in some cases. Agung’s 1963 eruption (above) was rated 5 on the scale, as was Pinatubo’s in 1991. But the index does not necessarily correlate to impact on climate: The eruption of Mount St. Helens in Washington in 1980 was of similar explosiveness but had little cooling effect because most of the ash and gas was expelled laterally rather than upward.

NASA researchers are mapping out a plan to monitor a Pinatubo-like event — “the scale of eruption that would lead to both ozone depletion and a lot of surface cooling,” said Paul A. Newman, a senior scientist at the agency who is helping to develop the plan.


A quarter-century ago, Pinatubo, a volcano in the Philippines, blew its top in a big way: It spewed a cubic mile of rock and ash and 20 million tons of sulfur dioxide gas into the atmosphere. The gas spread around the world and combined with water vapor to make aerosols, tiny droplets that reflected some sunlight away from the Earth. As a result, average global temperatures dropped by about one degree Fahrenheit for several years.

Powerful volcanic eruptions like Pinatubo’s in 1991, writes Henry Fountain in today's New York Times, are one of the biggest natural influences on climate. So NASA researchers and other scientists are planning a rapid-response program to study the next big one.

But the climate impact of a Pinatubo-size eruption is also a natural analog of an idea that has existed on the fringes of science for years: geoengineering, or intervening in the atmosphere to deliberately cool the planet.

One geoengineering approach would use high-flying jets to spray similar chemicals in the stratosphere. So by studying the next big volcanic eruption, scientists would also gain insights into how such a scheme, known as solar radiation management, or S.R.M., might work.

“This is important if we’re ever going to do geoengineering,” said Alan Robock, a Rutgers University researcher who models the effects of eruptions and who has been involved in discussions about the rapid-response project. “But even if there were no such thing as geoengineering, it’s still important to understand how volcanoes affect climate.”

The rapid-response effort would involve high-altitude balloon flights and other methods to gather data about an eruption as soon as possible after it begins and for several years afterward.

The idea has gained some urgency in recent weeks, since Mount Agung, a volcano in Bali, began erupting at the end of November. Agung’s last major eruption occurred in 1963, and should it fully blow with similar fury it could pump enough sulfur dioxide gas high enough into the atmosphere to have a measurable cooling effect. A huge eruption could also temporarily damage the ozone layer, which scientists would also study.

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