Two Looming Volcanic Eruptions Could Slow Climate Change, But They Aren't Going to Stop It

An aerial view of the volcanic cone that has formed in Lake Vui near the summit of Ambae Island, Vanuatu. Photo: AP
An aerial view of the volcanic cone that has formed in Lake Vui near the summit of Ambae Island, Vanuatu. Photo: AP

Following a pattern of everything being terrible in 2017, two volcanoes are primed to erupt along the western edge of the Ring of Fire.


Mt. Agung in Bali, Indonesia has forced 144,000 into shelters beyond the 7.5 mile exclusion zone, while the volcano on Ambae Island in Vanuatu has forced all 11,000 residents to evacuate, according to CNN. The rumbling volcanoes could turn paradise into paradise lost, sending lava bombs in all directions, incinerating rainforests and turning crystal waters muddy brown.

But they could also have another impact: temporarily slowing climate change. Scientists have known about volcanoes’ impact on the climate for a long time, but new research published this week shows how fleeting the chill of future eruptions could be.

The last time Mt. Agung erupted in 1963, it put a chill on global temperatures for a few years. The global average temperature dropped up to 0.7 degrees Fahrenheit in the years immediately following the eruption, which also left more than 1,700 dead and a devastated landscape in its aftermath.

When a volcano blows its top, it sends hundreds of thousand of tons of sulfur dioxide and ash into the stratosphere. Those fine particles remain suspended high above the planet for years, reflecting some of the incoming sunlight back into space. With less sunlight reaching Earth’s surface, there’s less energy to be trapped by greenhouse gases. So voila, cooling.

Mt. Agung’s 1963 eruption is hardly the only one to leave a mark on the climate record books. In 2014, scientists found that a handful of small eruptions since 2000 also played a role in slowing global warming.

Still other research has shown that cooling can extend to the oceans, further dampening the impacts of climate change. Take the 1991 eruption of Mt. Pinatubo, the second-largest eruption of the 20th century. It cooled the oceans so much, it actually caused sea levels to drop by six millimeters over two years.


Of course, those particles eventually drop out of the stratosphere. And when they do, the effects of carbon dioxide quickly reassert themselves. After the stratosphere cleared due to the Pinatubo eruption, sea level rise rates ticked back up, and have been accelerating since as climate models predicted they would.

And after the tamping down temperatures in the early 2000, global warming has roared onward. The planet has had back-to-back-to-back hottest years on record since 2014. This year is on track to be the second-hottest year on record for the globe.


The burbling volcanoes in Bali and Vanuatu are unlikely to knock the planet off that pace. But next year could be a different, slightly cooler story.

“The impact would be felt in 2018 and not 2017. It will take some months for the volcanic veil to spread out across the globe and hence the impacts on global climate to be felt,” Peter Thorne, a climate scientist at Maynooth University in Ireland, told Earther. “The duration of impact of volcanoes depends upon the magnitude but a good rule of thumb is a few years.”


Thorne and his colleagues published a timely study in Nature Climate Change on Monday about the need to improve how scientists model volcanoes in future climate simulations. Most models keep stratospheric cooling from volcanoes as a constant hum in the background, which isn’t how volcanoes work.

Temperature measurements of the globe have also sprung up in a time of relatively quiet volcano activity. Thorne’s study used a reconstruction of 2,500 years of volcanic activity to create a more realistic representation of what future eruptions could look like in the 21st century, and overlaid them on a climate scenario where humans start cutting carbon emissions by mid-century. While we may see more relatively cool years if volcanic activity picks up, the world still ultimately ends up on a path of ever-rising temperatures.


“Although the final destination does not change considerably (volcanoes are not a get out of jail free card for human-induced climate change), the pathway we follow to get there could be much bumpier than the projections in common use (that ignore volcanoes) imply,” Thorne said.

On top of that, more eruptions will also put more lives and infrastructure at risk. Eruptions can also block sunlight, reduce crop yields and triggering mass starvation. That’s what happened in 1816 following Mt. Tambora’s eruption in Indonesia, dubbed the year without a summer.


So yeah, volcanoes probably aren’t the best way to reduce the impacts of climate change. While the two impending eruptions in Bali and Vanuatu might provide a global warming respite for a year or two, humanity should probably get started on that whole reducing carbon emissions thing.

[Nature Climate Change]


Managing editor at Earther, writing about climate change, environmental justice, and, occasionally, my cat.



Counting on volcanic eruptions to slow down climate change is like hoping for a tsunami to put out a forest fire.