We're Destroying the Ocean's Ability to Buffer Us From Massive Volcanic Eruptions

The ocean stays cool on a hot day, but climate change will make that harder. Carl Court/AFP/Getty Images

Think back to the last time you spent a summer day at the ocean: The water was probably much cooler than the air. But if you stuck around to enjoy the sunset, you may have noticed that the temperature of the water dropped much more gradually than that of the air around you. The ocean plays a similar role with climate writ large, buffering the planet's temperatures from large swings—but climate change is interfering with its ability to so.

And that could be bad news when it comes to one of the sharpest types of climate swings, those caused by extremely powerful volcanic eruptions. That's according to a new paper published in the journal Nature Communications, which modeled the effect of the gigantic Mt. Tambora eruption of 1815 and a hypothetical future event of similar size on climate.

Particularly strong eruptions can cool the planet by a degree or two for a year or two. That's because powerful enough volcanoes can fill the top layer of the atmosphere with aerosols, tiny particles that grow clouds around them and reflect sunlight away from the Earth.

The 1815 eruption did just that and shaped history: It caused what's known as "the year without a summer" in 1816, an unusually cold and wet summer, particularly in North America and Europe. The strange weather conditions affected agriculture particularly strongly, including a potato blight in Ireland, causing food shortages and high prices. Some scholars have argued that the missing summer helped inspire Mary Shelley to write Frankenstein.

So the team behind the new paper modeled what happened in 1815 and the following few years. They found that the oceans moderated how the eruption influenced climate: They reduced the scale of the cooling, but made it last longer.

Then, the scientists looked at how a similar eruption might play out in the year 2085, after 68 more years of humans spitting out huge amounts of carbon dioxide. Currently, about 90 percent of the extra heat hanging around Earth because of climate change is being absorbed by the oceans. That's awfully convenient right now, but they can't keep warming up forever, and the heat is messing with the ocean's structure, reducing the amount of mixing between different depths.

And in the new paper, the scientists found that without as much mixing, the oceans weren't as able to modulate the climate implications of a Tambora-scale eruption. Their modeling predicted that such an eruption could cause almost half again as much cooling as the 1815 eruption did—which means that a "year without a summer" event in the future could be even worse than the disastrous summer of 1816. But at least we might get more Frankensteins.