Small Volcanoes Also Affect Climate
July 6, 2012

Small Volcanoes Also Affect Climate

Lawrence LeBlond for - Your Universe Online

An international team of researchers have found that even small volcanic eruptions can lead to a cooler climate if they coincide with weather systems such as monsoons, which boost aerosols produced by eruptions high into the atmosphere affecting global temperatures.

The research, led by scientists from the University of Saskatchewan in Canada, suggests that the previously held belief that only massively energetic eruptions could inject enough aerosols past the troposphere -- Earth´s closest atmospheric layer -- and up into the stable layers of the stratosphere, is wrong.

Research leader, Adam Bourassa, from the Institute of Space and Atmospheric Studies at U of S, said: “If an aerosol is in the lower atmosphere, it's affected by the weather and it precipitates back down right away.” But, once these aerosols reach the stratosphere, they “can persist for years, and with that kind of a sustained lifetime, it can really have a lasting effect,” he explained.

That effect is the scattering of incoming sunlight and the potential to cool the Earth´s surface, he added.

For their research, the team examined the June 2011 eruption of the Nabro volcano in Eritrea in northeast Africa. Wind carried the volcanic gas and aerosol into the path of the annual Asian summer monsoon. While it was previously assumed that storms could not pierce through the stratospheric layers, they found that volcanic gas and aerosol from the Nabro volcano did in fact make its way into the stratosphere, as was detected by the Canadian Space Agency´s OSIRIS instrument aboard the Swedish satellite Odin.

“There are only a few instruments that can measure stratospheric aerosols, and OSIRIS is one of them,” Bourassa said. “It´s become extremely important for climate studies, because we´ve captured more than a full decade of data. The longer it´s up, the more valuable it becomes.”

The aerosol load produced by the Nabro volcano pushed up through the stratosphere by the monsoon provided OSIRIS with its largest record of stratospheric aerosol in its ten-year run in orbit. Scientists hope that the latest data will help them create more accurate models of climate change.

Funding for this research, which appears in the July 6 issue of the journal Science, was provided by NSERC, the Canadian Space Agency, the US National Science Foundation, with support from the NASA Aura Science Team.