"For all their destructive power, most volcanic eruptions are local events.
Lava flows tend to reach only a few miles at most, while airborne ash and soot travel a little farther. But occasionally, larger eruptions can launch particles into the stratosphere, more than 6 miles above Earth’s surface.
When volcanic particles reach the stratosphere they stay aloft for a long time, reflecting sunlight and temporarily cooling the planet.
By understanding the history of these big eruptions, researchers can begin to place short cooling episodes and other discrete climate events into the context of large-scale climate patterns.
...“For eruptions that are intense enough to inject material into the stratosphere, there is a telltale signature in the sulfur isotope ratios of sulfate preserved in ancient ice layers,” explained Farquhar, who also has an appointment in UMD’s Earth System Science Interdisciplinary Center.
“By instead focusing on this distinct sulfur isotope signature, our new method yielded some surprising and useful results.
We found that prior reconstructions missed some stratospheric events and falsely identified others.”
...“This is a strength of our approach, because these events would have a climate impact but are missed by other methods,” Farquhar said.
“We have made a significant improvement to the reconstruction of large stratospheric eruptions that occurred over the past 2,600 years.
This is critically important for understanding the role of volcanic eruptions on climate and possibly for understanding certain events in human history, such as widespread famines.
It can also help to inform future climate models that will take large volcanic events into account.”
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