Is Eyjafjallajökull Good for the Climate?

By now you've probably heard about the eruption of a volcano in Iceland by the name of Eyjafjallajökull (pronounced "EYE-a-fyat-la-yu-goot" for all you non-Icelandic speakers out there). And you likely know of the nearly unprecedented effect it has had on European air travel. But what you may not be aware of is the effect it's having on our climate.

Past volcanic eruptions were reported to have a noticeable global cooling effect. In 1991, when Mount Pinatubo spewed ash for nearly two weeks in the Philippines, it injected about 20 million tons of sulfur dioxide (SO₂) into the stratosphere, which decreased air temperatures over the northern hemisphere the following summer by as much as 2 degrees Celsius. Globally, Pinatubo cooled the planet nearly 0.5 degrees Celsius, effectively negating the impact of greenhouse gases emitted from 1991 to 1993.

So what is it that caused Pinatubo to affect the climate in this way? It has to do with the release of SO₂ into the stratosphere. Following an eruption, the SO₂ emissions are quickly converted to sulfuric acid (H₂SO₄), which then condenses in the stratosphere to form fine sulfate aerosols. These sulfur rich particles have a long shelf life, sometimes remaining for as much as a few years in the stratosphere. While there, they reflect the energy of the sun back into space, thereby cooling the Earth's lower atmosphere, or troposphere. This is precisely the effect suggested by a variety of controversial geoengineering proposals that are aimed at mitigating the effects of global warming.

Although Eyjafjallajökull still has a large enough plume of ash to be recorded by NASA satellites, it pales in comparison to Pinatubo. Emitting around 3,000 tons of SO₂ each day, Iceland's mountain of magma has a long way to go before it even comes close to the 20 million tons released by Pinatubo.

There's another key atmospheric ingredient emitted by volcanoes: carbon dioxide (CO₂). But current estimates say that Eyjafjallajökull is ejecting just 150,000-300,000 tons of CO₂ each day, placing it on par with the daily emissions of a small to mid-size European economy. For comparison, 42 million tons of CO₂ were put into the atmosphere as a result of Pinatubo.

An interesting consideration is not just the toxic gas released by Eyjafjallajökull but its indirect effect on reducing CO₂ emissions as a result of grounded flights. Nonetheless, a recent infographic from Information is Beautiful (re-posted below) illustrates that the net effect doesn't drastically change the outlook for our climate.



Some have speculated that it is possible the current cough of Eyjafjallajökull could trigger an eruption of the neighboring Katla volcano as it did in 1823. However, scientists are quick to emphasize there is no evidence linking the two magmatic vessels.

Unfortunately, it doesn't look like Eyjafjallajökull will offer any respite from global climate change in the near future.