Climate: Tracking atmospheric aerosols

New satellite data shows volcanoes are a bigger factor than industrial emissions, at least high in the atmosphere

Alaska's Redoubt Volcano erupting in 1990. Photo courtesy USGS/R.J. Clucas.
Alaska’s Redoubt Volcano erupting in 1990. Photo courtesy USGS/R.J. Clucas.

By Summit Voice

FRISCO — Scientists have long known that aerosols can have a major effect on climate, and with measurements from sensitive satellite-based instruments, they’re getting a better handle on the formation, distribution and sources of various sulfur compounds in the atmosphere.

In a new study, researchers with the Karslruhe Institute of Technology say they’ve compiled one of the most comprehensive overview of sulfur dioxide measurements.

“Sulfur compounds up to 30 km altitude may have a cooling effect,” said KIT researcher Michael Höpfner, explaining that sulfur dioxide and water vapor react to sulfuric acid that forms aerosols, that reflect solar radiation back into universe.

The tools help pinpoint compounds like carbonyl sulfide, a gas produced by organisms in the oceans that disintegrates at altitudes higher than 25 km and provides for a basic concentration of sulfur dioxide.

The increase in the stratospheric aerosol concentration observed in the past years is caused mainly by sulfur dioxide from a number of volcano eruptions.

“Variation of the concentration is mainly due to volcanoes,” Höpfner said. “We can now exclude that anthropogenic sources, e.g. power plants in Asia, make a relevant contribution at this height,” He said.

Devastating volcano eruptions, such as those of the Pinatubo in 1991 and Tambora in 1815, had big a big effect on the climate. The present study also shows that smaller eruptions in the past ten years produced a measurable effect on sulfur dioxide concentration at altitudes between 20 and 30 km.

“The new measurement data help improve consideration of sulfur-containing substances in atmosphere models. This is also important for discussing the risks and opportunities of climate engineering in a scientifically serious manner,” he added.

The new data came from an interferometer aboard  the European environmental satellite ENVISAT that supplied data from 2002 to 2012. Around the clock, the instrument measured temperature and more than 30 atmospheric trace gases.


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