A previously unknown volcanic eruption helped trigger a decade of global cooling 200 years ago, according to a new study published by a scientific team including a UC San Diego researcher.
The eruption took place in 1809, according to the study, published last week in the scientific journal Geophysical Research Letters. A second eruption, which had been previously documented, took place in 1815 in Indonesia. Together, the eruptions caused a decade of unusually cool weather.
The team took ice samples from Greenland and Antarctica. The samples contained unusually high levels of sulfuric acid, a telltale sign of a volcanic eruption.
The team included Mark Thiemens, UCSD's dean of physical sciences. Others were David Ferris, a researcher from South Dakota State, and Mélanie Baroni of L'Université Paul Cézanne in France.
Volcanos spew large amounts of sulfur-containing gases into the atmosphere that cause formation of extremely small particles, called "aerosols," that block the sunlight. Very large eruptions can cause these aerosols to reach the stratosphere, where they can be circulated globally.
It's not known exactly where the first eruption took place, but the evidence points to somewhere in the tropics, the study said.
Moreover, the study noted, the cooling effect from these eruptions is the same as that proposed by advocates of "geoengineering" to counteract global warming.
"The global-cooling effect of stratospheric volcanic aerosols provides the physical basis for the geoengineering proposition to counteract the human-enhanced greenhouse warming by injecting (sulfur dioxide) into the stratosphere," the study stated.
Geoengineering advocates, including the authors of "SuperFreakonomics," say it promises to be a much more effective and less costly fix to global warming than reducing the amount of carbon dioxide in the atmosphere.
Opponents of geoengineering have bitterly criticized the proposal as unworkable and a diversion from dealing with the problem.
Congress is scheduled to consider geoengineering Thursday at a hearing of the House Committee on Science and Technology. More information is available at http://house.science.gov.
Call staff writer Bradley J. Fikes at 760-739-6641. Read his blogs at bizblogs.nctimes.com.
