Cooling from volcanic eruptions likely underestimated

A new study from the University of Cambridge (UK) has determined that the temporary, global cooling effect from volcanic eruptions has been underestimated by at least a factor of two and possibly as high as a factor of four.

When certain volcanoes erupt, they can send sulfuric gases high up into the atmosphere and stratosphere. The particles that are produced from these aerosols end up reflecting more sunlight back into space, which means less sunlight is reaching the surface, leading to a cooling effect.

The massive 1991 eruption of Mount Pinatubo in the Philippines caused a period of global cooling (note the sharp downward peak of the stratospheric aerosols in the early 1990s on the graph below), but large eruptions like this are rare.

The research team found that even small-magnitude eruptions, which are much more common, are responsible for as much as half of the volcanic forcing of the climate system.

Key excerpts from the EurekAlert story.....

Their simulations show that the impacts of volcanic eruptions on climate, including global surface temperature, sea level and sea ice extent, are underestimated because current climate projections largely underestimate the plausible future level of volcanic activity.

For the median future scenario, they found that the effect of volcanoes on the atmosphere, known as volcanic forcing, is being underestimated in climate projections by as much as 50%, due in large part to the effect of small-magnitude eruptions.

“We found that not only is volcanic forcing being underestimated, but small-magnitude eruptions are actually responsible for as much as half of the volcanic forcing,” said first author May Chim. “These small-magnitude eruptions may not have a measurable effect individually, but collectively, their effect is significant.

“I was surprised to see just how important these small-magnitude eruptions are – we knew they had an effect, but we didn’t know it was so large.”

Report a Typo