A photo taken on January 25, 2018 from the city of Legazpi, Albay province, south of Manila, shows a fiery fountaining during an eruption of the Mayon volcano as it emits molten lava. Philippine authorities who have declared a no-go zone around an erupting volcano said January 25 they will remove all holdouts, by force if necessary, to avoid casualties after tens of thousands of other residents fled to safety.

A NASA climate simulation shows the effect of extremely large volcanic eruptions called "flood basalt eruptions" on Earth's climate.

Flood basalt (or plateau basalt) are thick successions of basalt eruption that flood vast areas of the Earth, covering broad regions with flat lying lava surfaces. An example of this is the Columbia River basalts in the northwest United States and the Deccan traps in India, according to the journal ScienceDirect.

NASA warns that these high-volume eruptions could significantly warm Earth's climate and devastate the ozone layer, as reported by SciTech Daily. This finding is contrary to NASA's 2015 study which suggests that volcanic eruptions cool the Earth's climate.

"We expected intense cooling in our simulations," said Scott Guzewich of NASA's Goddard Space Flight Center in Greenbelt, Maryland. "However, we found that a brief cooling period was overwhelmed by a warming effect."

The recent simulation also suggests that flood basalt eruptions are common on other terrestrial worlds in our solar system, such as Mars and Venus, and may have helped warm their climates.

Destructive to Ozone Layer

 

The simulations indicate that the potential magnitude of destruction to Earth's ozone layer caused by flood basalts is "about two-thirds reduction over global average values, roughly equivalent to the whole planet having an ozone thinning comparable to a severe Antarctic ozone hole," said Guzewich.

Using the Goddard Earth Observing System Chemistry-Climate Model, researchers simulated a four-year-long phase of the Columbia River Basalt (CRB) eruption that occurred some time between 15 million and 17 million years ago in the Pacific Northwest of the United States. The model calculated the effects of the eruption on the Earth's troposphere and stratosphere, and assumed that "explosive events happened four times per year", releasing about 80% of the eruption's sulfur dioxide gas.

Researchers also found that there was net cooling for about two years before the warming overwhelms the cooling effect on a global scale. "The warming persists for about 15 years (the last two years of the eruption and then another 13 years or so)," Guzewich notes.

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A Brief Cooling Period to a Warming Effect

 

The new simulation was considered the most comprehensive yet done for flood basalt eruptions. It integrates the effects of atmospheric chemistry and climate dynamics on each other, and reveals important details not found in earlier simulations.

According to Guzewich, the aerosols converted from gas molecules reflect visible sunlight, which produces the initial cooling effect as a result. However, it also absorbs infrared radiation, which warms the atmosphere especially in the upper troposphere and lower stratosphere.

"Warming this region of the atmosphere allows water vapor (that's normally confined near the surface) to get mixed into the stratosphere (which is normally very dry). We see a 10,000% increase in stratospheric water vapor," Guzewich explains.

Aside from emitting infrared radiation that warms the planet's surface, surge of water vapor into the stratosphere also helps explain the severity of the ozone layer depletion which "happens in a couple different ways."

"Second, all that water in the stratosphere also helps destroy ozone with the hydroxyl (OH) radical."

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