I was asked by a colleague about what is expected to happen as marine bunker fuels are desulfurized over the coming several years. My first response was that it would reduce the SO2 emissions and so the sulfate, and since sulfate adds to cooling, this would suggest the desulfurization would lead to a warming influence.
But then, the key to cloud brightening is addition of CCN in relatively unpolluted regions (so yes, over remote oceans), but is not much of the ship traffic in relatively polluted regions? Experiments do seem to indicate that over-saturation of CCN tends to lead to cloud clearing--so basically we are in the Goldilocks situation--one needs to have neither too few CCN nor too many to get cloud brightening. So, might it be that in some polluted regions, reducing the SO2 emissions from marine sources might actually lead to an increase in clouds/cloud brightness? Has anyone done a really careful analysis of this? Do we really have good quantitative estimates of what might happen? And how might all of this play out as the other sources of SO2 are changing? Perhaps Stephen Salter, John Latham, Alan Gadian, et al. have a paper(s) on this that I have missed. Mike MacCracken -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
