A search for large-scale effects of ship emissions on clouds and radiation in satellite data
This publication was chosen as research highlight by Nature Climate Change
Aerosols released by ships can locally induce brighter or even new clouds, but it has been unclear whether this phenomenon extends far beyond the narrow ship tracks visible in satellite images, which might be expected if aerosols are blown far downwind.
To address this issue, Dr. Karsten Peters (formerly at the Max Planck Institute for Meteorology in Hamburg, Germany), and colleagues studied the climatic effects of ship-produced aerosols around major shipping corridors cutting across subtropical and tropical oceans, where air quality is otherwise good.
Using satellite-derived data, they investigated cloud properties along the shipping lanes as well as in upwind and downwind regions, taking into account wind trajectories and large-scale meteorological observations.
They failed to detect statistically significant effects of shipping emissions on large-scale cloud distributions in regions close to shipping lanes over the study period (2005 - 2007). They therefore concluded that, for the regions considered, such emissions have at most an effect on cloud presence and formation which is small compared to the natural variability, except perhaps in the immediate vicinity of ship tracks.
(Image courtesy: 
http://heliophage.wordpress.com/2009/08/20/the-international-maritime-organisations-plans-to-warm-the-world/)
Original paper:
Peters, K., J. Quaas, and H. Graßl: J. Geophys. Res., 116, D24205, doi:10.1029/2011JD016531
Journal of Geophysical Research: http://www.agu.org/journals/jgr/
Contact:
Dr. Karsten Peters
Monash University, Australia
Email: 
karsten.peters@zmaw.de
Prof. Dr. Johannes Quaas
University of Leipzig
Phone: +49 (0)341 97 32852
Email: johannes.quaas@uni-leipzig.de
Prof. Dr. Hartmut Graßl
Max Planck Institute for Meteorology
Phone: +49 (0)40 41173 151
Email: hartmut.grassl@zmaw.de
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