Kilauea's Eruption Is Big, but Not Big Enough to Cool the Planet

Gases from big eruptions can scatter sunlight and lower temperatures.

Lava from a fissure slowly advances northeast after the eruption of Hawaii's Kilauea volcano near Pahoa, on May 5, 2018. 

Photographer: Handout/Getty Images North America

Hawaii’s Kilauea volcano has ruptured the Earth in at least 17 places, burning homes with super-hot lava. More than 2,000 Hawaiians have evacuated, and the U.S. Geological Survey has issued warnings that “potentially lethal concentrations of sulfur dioxide gas” may leak downwind as far as a kilometer (0.6 mile) from the lava vents. President Donald Trump has declared a state of emergency.

But it’s not yet big enough to slow global warming, as past volcanic eruptions have.

In much larger doses, volcanic gases can temporarily change the global atmosphere. Sulfur dioxide—the same chemical regulated by the U.S. Environmental Protection Agency as a pollutant from coal-fired power plants—can, in sufficient quantities, at a high-enough altitude, scatter enough sunlight to lower global average temperatures slightly for months,even for a couple of years.

“Barring a violent explosion or eruption, Kilauea won’t affect our climate. You have to blast particles high into the stratosphere to cool the Earth. That’s the only way the dust stays in the air long enough to cool the planet,” said Rob Jackson, professor and chair of the Earth System Science department at Stanford University.

Park visitors watch as an ash plume rises from the Halemaumau crater, within the Kilauea volcano summit, on May 9, 2018.
Photographer: Mario Tama/Getty Images North America

Climate scientists have long understood the effects of such massive eruptions on the atmosphere. In June 1991, Mount Pinatubo in the Philippines blew 15 million tons of sulfur dioxide into the stratosphere, lowering global average temperatures about 1 degree F (0.6 degree C) over the following two years.

Scientists look warily toward a possible future when, with manmade warming unabated, nations may purposely seed the upper atmosphere with sulfur dioxide to lower temperatures.

A major National Research Council study in 2015 concluded that despite the availability of such geoengineering tools, “there is no substitute for dramatic reductions in the emissions of CO2 and other greenhouse gases to mitigate the negative consequences of climate change.”

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