Massive volcanoes could cool Earth more in a warming world

Science Mag:

Not sure about the “warming world” but increased volcanic activity WILL cool things down.

Professor David Dilley has been saying this for years, and predicts an increase in volcanic activity related to asronomical cycles of sun and moon. PROFESSOR DILLEY’S [LONG, BUT IT’S WORTH IT] VIDEO

There are few forces on Earth more powerful than a large volcanic eruption. At their most potent, volcanoes inject millions of tons of Sun-blocking particles high into the atmosphere that can cool Earth for nearly 5 years, endangering crops and leading to “years without summer.” The most recent, the Philippines’s Mount Pinatubo eruption in 1991, caused a temporary 0.5°C drop in global temperatures.

Yet it’s become increasingly clear that even these monumental forces are being altered by human-driven climate change. Declining ice cover can trigger more frequent eruptions near the poles, in Iceland and elsewhere. And an increasingly layered ocean will allow more volcano-induced cooling to linger at Earth’s surface.

Now, a new study suggests increased greenhouse gases will help the plumes from large eruptions reach higher, spread faster, and reflect more sunlight, causing more abrupt and extreme cooling.

Well, well, well.

Before humanity started in on its planet-altering course, volcanoes were one of the biggest climate players. Over the long term, they belched carbon dioxide from Earth’s interior, causing warming. But in the short term, their sulfur gases often react with water to form highly reflective particles called sulfates, triggering spells of global cooling. Dark smudges of ash littering ice cores—our best evidence of these early eruptions—are a dim reflection of the wild weather left in their wake.

But the opposite is also true, it turns out: Climate can have a big impact on volcanoes. In the new study, Thomas Aubry, a geophysicist at the University of Cambridge, and colleagues combined computer simulations of idealized volcanic eruptions with a global climate model. They simulated the response to plumes released from midsize and large volcanoes both in historical conditions and by 2100, in a scenario when Earth is predicted to warm very rapidly.

The researchers found two countervailing trends. Normally just one or two midsize volcanic eruptions shoot through the troposphere each year, bypassing this cradle of Earth’s weather to reach the stratosphere, the calm, dry zone above. As reflective particles spread through the stratosphere, they cause a small spurt of global cooling. But when the troposphere warms, it expands in height, eventually putting the stratosphere out of reach for these eruptions.

“It’s as if regulation basketball hoops around the world were suddenly raised a few inches, making it that much harder to score,” says Benjamin Black, a volcanologist at Rutgers University, New Brunswick, who is not affiliated with the study.

The story changes with Pinatubo-scale eruptions, however. In a world that warmed 6°C by 2100—an increase that matches only the most dire, and unlikely, projections of the latest Intergovernmental Panel on Climate Change report—the troposphere would grow 1.5 kilometers in height.

But ultramassive eruptions would still be able to punch through to the stratosphere; what’s more, their gases would actually reach higher and travel faster than in the present climate, amplifying their cooling effect by 15%, the researchers report this month in Nature Communications. The reasons why come down to the bizarro world that is the stratosphere, Aubry says.

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