Can/should GE fill the breach? - G The .pdf file is on http://www.atmos-chem-phys.net/12/2399/2012/acp-12-2399-2012.pdf.
Atmos. Chem. Phys., 12, 2399-2408, 2012 www.atmos-chem-phys.net/12/2399/2012/ doi:10.5194/acp-12-2399-2012 © Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 License. Decreasing particle number concentrations in a warming atmosphere and implications F. Yu1, G. Luo1, R. P. Turco2, J. A. Ogren3, and R. M. Yantosca4 1Atmospheric Sciences Research Center, State University of New York at Albany, Albany, New York, USA 2Department of Atmospheric and Oceanic Sciences, University of California at Los Angeles, Los Angeles, California, USA 3Global Monitoring Division (GMD), Earth System Research Laboratory (ESRL), NOAA, Boulder, Colorado, USA 4School of Engineering and Applied Sciences, Harvard University, Boston, Massachusetts, USA Abstract. New particle formation contributes significantly to the number concentration of condensation nuclei (CN) as well as cloud CN (CCN), a key factor determining aerosol indirect radiative forcing of the climate system. Using a physics-based nucleation mechanism that is consistent with a range of field observations of aerosol formation, it is shown that projected increases in global temperatures could significantly inhibit new particle, and CCN, formation rates worldwide. An analysis of CN concentrations observed at four NOAA ESRL/GMD baseline stations since the 1970s and two other sites since 1990s reveals long-term decreasing trends that are consistent in sign with, but are larger in magnitude than, the predicted temperature effects. The possible reasons for larger observed long-term CN reductions at remote sites are discussed. The combined effects of rising temperatures on aerosol nucleation rates and other chemical and microphysical processes may imply substantial decreases in future tropospheric particle abundances associated with global warming, delineating a potentially significant feedback mechanism that increases Earth's climate sensitivity to greenhouse gas emissions. Further research is needed to quantify the magnitude of such a feedback process. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
