Storms, volcanoes could cool the Earth
Jul 5, 2012 / 4:41 pm
An international team led by University of Saskatchewan researchers says small volcanic eruptions could cool the climate.
The team says aerosols, minute droplets of sulphuric acid, from relatively small volcanic bursts can be shot into the high atmosphere by weather systems such as monsoons.
"If an aerosol is in the lower atmosphere, it's affected by the weather and it precipitates back down right away," lead researcher Adam Bourassa, who is with the university's Institute of Space and Atmospheric Studies, said in a news release Thursday.
"Once it reaches the stratosphere, it can persist for years, and with that kind of a sustained lifetime, it can really have a lasting effect."
The result, he said, is the scattering of incoming sunlight and the potential to cool the Earth's surface.
Bourassa said that until now it was thought that a massive eruption was needed to inject aerosols past the troposphere, the turbulent atmospheric layer closest to the Earth, into the stable layers of the stratosphere higher up.
Researchers noted that the massive eruption of Mount Pinatubo in the Philippines in 1991 temporarily dropped temperatures by half a degree Celsius worldwide.
The team, including scientists from Rutgers University in New Jersey, the National Center for Atmospheric Research in Colorado and the University of Wyoming, looked at the June 2011 eruption of the Nabro volcano in Eritrea in northeast Africa.
The researchers found that wind carried the volcanic gas and the droplets of sulphuric acid into the path of the annual Asian summer monsoon.
Dust from the Nabro volcano, being slightly heavier, settled out. But the monsoon lofted volcanic gas and the lighter liquid droplets into the stratosphere where they were detected by the Canadian Space Agency's OSIRIS instrument aboard the Swedish satellite Odin. The Nabro volcano caused the largest stratospheric aerosol load ever recorded by OSIRIS in its more than 10 years of flight.
Researchers say they hope the findings will allow more accurate models of climate behaviour and change.
The findings appear in Friday's issue of the journal Science.
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