The climate effects of high-latitude volcanic eruptions: Dr. Ben Kravitz
In August 2008, in the Aleutian Islands, there was a small high-latitude eruption, the eruption of Kasatochi Volcano, which put about 1½ megatons of sulfur dioxide into the stratosphere. And then the following year in June, there was the eruption of Sarychev in the Kuril Islands, which put about the same amount. The climate effects weren’t detectable, both according to observations and according to climate model simulations that we did.
So we wanted to figure out what it would take, basically, for a high-latitude eruption to have climate effects. And so we used a climate model, and we first decided to do five megaton eruptions, both paralleling the eruptions of Sarychev and Kasatochi, so at the same time of year. And we found out that Sarychev at 5 megatons gave us climate effects, but Kasatochi didn’t. That suggested to us that the time of year of a high-latitude eruption actually plays a major role in what the climate effects will be.
In addition, we did climate model simulations of eruptions in the winter and the spring, both of 5 megatons. So we have a 5 megaton eruption in each season, and we looked at the climate effects according to the climate model. What we found is that the summer was the only one where we got noticeable climate effects at a level of statistical significance.
We concluded that, at least for the size of the eruptions that we looked at, the time of year actually plays a more important role in determining whether the eruption will have climate effects than the amount.