There is yet another article that documents that the role of humans in the climate system is much more than the radiative effect of CO2 and a few other gases (h/t to Marc Morano). This new study bolsters our conclusions in
Pielke Sr., R., K. Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D. Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E. Philip Krider, W. K.M. Lau, J. McDonnell, W. Rossow, J. Schaake, J. Smith, S. Sorooshian, and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases. Eos, Vol. 90, No. 45, 10 November 2009, 413. Copyright (2009) American Geophysical Union
The Scientific American article, however, still misinterprets climate system heat changes (and climate change more generally) as dominated by added CO2.
The new article is
Stratospheric Pollution Helps Slow Global Warming By David Biello July 22 2011 in Scientific American
with the headline
Particles of sulfuric acid–injected by volcanoes or humans–have slowed the pace of climate change in the past decade.
My comment on this statement is that the ejection of aerosols from humans into the stratosphere IS part of human climate change. The implication from the term “pace” is that the radiative effect of CO2 and a few other greenhouse gases is climate change. It is NOT as we summarize in our EOS article
Although the natural causes of climate variations and changes are undoubtedly important, the human influences are significant and involve a diverse range of first-order climate forcings, including, but not limited to, the human input of carbon dioxide (CO2). Most, if not all, of these human influences on regional and global climate will continue to be of concern during the coming decades.
Excerpts from the Scientific American text read [highlights added]
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.
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. The effect also illustrates one proposal for so-called geoengineering—the deliberate, large-scale manipulation of the planetary environment—that would use various means to create such sulfuric acid aerosols in the stratosphere to reflect sunlight and thereby hopefully forestall catastrophic climate change.
But that points up another potential problem: if aerosol levels, whether natural or human-made, decline in the future, climate change could accelerate—and China is adding scrubbing technology to its coal-fired power plants to reduce SO2 emissions and thereby minimize acid rain. In effect, fixing acid rain could end up exacerbating global warming. China “could cause some decreases [in stratospheric aerosols] if that is the source,” Neely says, adding that growing SO2 emissions from India could also increase cooling if humans are the dominant cause of injecting aerosols into the atmosphere. On the other hand, “if some volcanoes that are large enough go off and if they are the dominant cause [of increasing aerosols], then we will probably see some increases” in cooling.
First, the statement that water vapor has been decreasing is remarkable. An increase in atmospheric water vapor is central to the hypothesis that the radiative effect of added CO2 would result in global warming that is significant in terms of effects on society. A lack of such an increase in water vapor is in contradiction to the 2007 IPCC model projections.
Second, the claim that “fixing acid rain could end up exacerbating global warming” somehow seems to suggest we should consider geoengineering that retains these aerosol emissions in order “to forestall catastrophic climate change“. This is an absurd claim. I wrote about this in my post
I ended that post with the conclusion
Thus, when I see attempts to delay implementation of any air quality improvement, which will cost lives, in order to provide a climate effect (i.e. through the delay in reducing sulphate emissions), we need to recognize that the priorities of those making such climate recommendations are misplaced.