When the weather suddenly got colder in Northern Europe a few centuries ago, some people blamed witchcraft. But now an international team of scientists has identified a more likely cause of the 'Little Ice Age':
"The new study suggests that the onset of the little Ice Age was caused by an unusual, 50-year-long episode of four massive tropical volcanic eruptions," According to a statement from the American Geophysical Union. These "erupting volcanoes...cooled the planet by ejecting shiny aerosol particles that reflected sunlight back into space."
Normally, the effects would persist for only a few years. But study co-author Bette Otto-Bliesner, a scientist with the National Center for Atmospheric Research, told the Daily Mail that "The eruptions could have triggered a chain reaction, affecting sea ice and ocean currents in a way that lowered temperatures for centuries."
The cold period, which was kicked off in the 13th century and lasted until the 19th, helped define Northern European life from before the Renaissance through the Industrial Revolution—ever wondered why the Old Masters painted so many winter scenes? The research was “the first time anyone has clearly identified the specific onset of the cold times marking the start of the Little Ice Age,” said Professor Gifford Miller, the geologist at the University of Colorado, Boulder who led the study.
To get these dates, the team radiocarbon-dated dead plants from receding ice caps on Baffin in Canada. They found that one group of the plants had died from 1275-1300 A.D. and another around 1450 A.D.
Then the researchers compared the dates to the layers of ice in a glacial lake in Iceland. The stratified ice shows the passage of time and changes in the environment, sort of like the rings on a tree trunk—when the scientists saw volcanic ash deposits at the late-13th century and the 15th century marks, it was clear what had caused the plants to die.
The scientists published their research in the January 31 issue of Geophysical Research Letters.