Volcanic eruptions of the past provide new clues about climate change

A team of researchers led by the University of Copenhagen recently looked at volcanic eruptions on Earth for the last 60,000 years. To estimate the number and intensity of these eruptions, the scientists looked at ice cores drilled in Antarctica and Greenland. Gases trapped in the ice cores revealed the surprising history of volcanoes. 

“We haven’t experienced any of history’s largest volcanic eruptions. We can see that now. Eyjafjellajökull, which paralyzed European air traffic in 2010, pales in comparison to the eruptions we identified further back in time. Many of these were larger than any eruption over the last 2,500 years,” said Anders Svensson of Niels Bohr Institute.

In the span of time examined, the scientists found 85 large global eruptions, 69 of which were more explosive than the largest volcanic eruption in recorded history – Mt. Tambora in Indonesia in 1815. Mt. Tambora caused significant cooling in its wake, along with famine, drought, tsunamis, and the deaths of 80,000 people. 

“The new 60,000-year timeline of volcanic eruptions supplies us with better statistics than ever before,” said Svensson.

“Now we can see that many more of these great eruptions occurred during the prehistoric Ice Age than in modern times. Because large eruptions are relatively rare, a long timeline is needed to know when they occur. That is what we now have.”

Although the history of volcanic eruptions gives us valuable information, the data needed to predict the next major volcanic eruption isn’t forthcoming. 

“Three eruptions of the largest known category occurred during the entire period we studied, so-called VEI-8 eruptions (see fact box). So, we can expect more at some point, but we just don’t know if that will be in a hundred or a few thousand years. Tambora sized eruptions appears to erupt once or twice every thousand years, so the wait for that may be shorter.”

The data does provide some insight into how the climate changed after each eruption, such as how much material in the atmosphere drove what amount of cooling. 

“Ice cores contain information about temperatures before and after the eruptions, which allows us to calculate the effect on climate. As large eruptions tell us a lot about how sensitive our planet is to changes in the climate system, they can be useful for climate predictions,” explained Svensson.

The study is published in the journal Climate of the Past.

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By Zach Fitzner, Earth.com Staff Writer