Monstrous Volcano Eruption that Lasted a Millennium Covered Pacific Northwest in Lava 16 Million Years Ago

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Smoke rises from the Popocatepetl as it spews incandescent volcanic material on the outskirts of Puebla, Mexico. Reuters

In 1815, a volcano erupted in Indonesia, launching the world into the Game of Thrones–esque “Year Without a Summer.” The planet was enveloped in a dark cloud of dust, which warped the climate and caused the second coldest year since the Middle Ages. Across all continents, crops withered and people suffered.

But this event was nothing compared to what researchers at Washington State University just discovered.   

Klarissa Davis, John Wolff, and their team found evidence that a massive eruption took place in the Pacific Northwest in what are now Washington and Oregon millions of years ago. The team reached this conclusion by examining chips of volcanic glass—which Wolff describes as “the closest thing to original magma that it’s possible to find”—in ash deposits of the Columbia River Basalts. They estimate that the event resulted in between 242 and 305 billion tons of sulfur dioxide over tens of thousands of years. That is thousands of times the sulfur dioxide eruption that led to the year without a summer, to say nothing of the 40,000 cubic kilometers of lava.

Along with striking fear into the hearts of people everywhere, understanding this eruption could help resolve a question in the history of the Earth’s climate.

Volcanic eruptions can—perhaps counterintuitively—cool the climate. And Wolff points out that the eruption his team describes coincided with an intense period of consistent cooling.

“At that time, Earth was at the peak of a warm phase called the Miocene Climatic Optimum,” Wolff told Newsweek. This peak, Wolff said, was broken up by several hundred thousand years of cooler climate. Wolff and his group believe that the cooling caused by this massive set of eruptions could explain that change. Wolff adds that this study does not prove the eruptions were the cause.

The fact that sulfur dioxide cools the climate raises a question scientists have considered for some time: Could sulfur dioxide be used to intentionally cool the climate for the Earth’s benefit?

“In principle it should certainly work,” Wolff said. “However there are side effects that may be unacceptable, acid rain being the most obvious one.”

Whether or not that line of work proves fruitful in mitigating human-induced climate change, this work offers a fascinating snapshot of a distant, surreal event from before humans walked the Earth.

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