STRATOSPHERIC POLLUTER?: Eruptions like that of Soufriere Hill in Montserrat pictured here may be adding enough aerosols to the stratosphere recently to slow global warming--or coal burning in China may be the primary culprit. Image: Courtesy of NASA
Scientific American: Particles of sulfuric acid–injected by volcanoes or humans–have slowed the pace of climate change in the past decade
Despite significant pyrotechnics and air travel disruption last year, the Icelandic volcano Eyjafjallajokull simply didn’t put that many aerosols into the stratosphere. In contrast, the eruption of Mount Pinatubo in 1991, put 10 cubic kilometers of ash, gas and other materials into the sky, and cooled the planet for a year. Now, research suggests that for the past decade, such stratospheric aerosols—injected into the atmosphere by either recent volcanic eruptions or human activities such as coal burning—are slowing down global warming.
“Aerosols acted to keep warming from being as big as it would have been,” says atmospheric scientist John Daniel of the National Oceanic and Atmospheric Administration’s (NOAA) Earth System Research Laboratory, who helped lead the research published online in Science on July 21. “It’s still warming, it’s just not warming as much as it would have been.”
… Combined with a decrease in atmospheric water vapor and a weaker sun due to the most recent solar cycle, the aerosol finding may explain why climate change has not been accelerating as fast as it did in the 1990s.
More … http://www.scientificamerican.com/article.cfm?id=stratospheric-pollution-helps-slow-global-warming
http://www.sciencemag.org/content/early/2011/07/20/science.1206027.abstract
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The Persistently Variable “Background” Stratospheric Aerosol Layer and Global Climate Change
Note, not WattsUpWithat but “Science Magazine” …
http://www.sciencemag.org/content/early/2011/07/20/science.1206027.abstract
Abstract
Recent measurements demonstrate that the “background” stratospheric aerosol layer is persistently variable rather than constant, even in the absence of major volcanic eruptions. Several independent data sets show that stratospheric aerosols increased in abundance since 2000. Near-global satellite aerosol data imply a negative radiative forcing due to stratospheric aerosol changes over this period of about –0.1 W/m2, reducing the recent global warming that would otherwise have occurred. Observations from earlier periods are limited but suggest an additional negative radiative forcing of about –0.1 W/m2 from 1960 to 1990. Climate model projections neglecting these changes would continue to overestimate the radiative forcing and global warming in coming decades if these aerosols remain present at current values or increase.