Hello Oliver, Thank you for the correction. Apologies!
I must have muddled-up the authorships of the various papers. All Best Wishes from yr semi-senile friend, John. John Latham Address: P.O. Box 3000,MMM,NCAR,Boulder,CO 80307-3000 Email: lat...@ucar.edu or john.latha...@manchester.ac.uk Tel: (US-Work) 303-497-8182 or (US-Home) 303-444-2429 or (US-Cell) 303-882-0724 or (UK) 01928-730-002 http://www.mmm.ucar.edu/people/latham ________________________________________ From: geoengineering@googlegroups.com [geoengineering@googlegroups.com] on behalf of O Morton [omeconom...@gmail.com] Sent: 02 April 2013 22:25 To: geoengineering@googlegroups.com Cc: omeconom...@gmail.com Subject: Re: [geo] SRM and droughts in the Sahel - rectification Dear John In my piece I didn't use the term SRM, which I try to avoid, and specifically addressed the application of cloud brightening in such a scenario Best o On Tuesday, 2 April 2013 20:09:16 UTC+1, JohnLatham wrote: SRM and droughts in the Sahel, Hello Oliver, Jim, Andy, and All, Good to read the several interesting results and arguments, hopefully to be developed further. However, I’d like to request rectification of a common tendency for the terms SRM, and sometimes climate geoengineering to be regarded as synonymous with stratospheric sulphur seeding. The latter is without question the best known SRM technique, and clearly has a significant likelihood of proving useful, but other SRM ideas, including Marine Cloud Brightening (MCB) and Russell Seitz’s microbubble technique also have promise and should not be disregarded at this stage. Bala, Caldeira et al. found that extensive oceanic cloud seeding via MCB did not significantly reduce rainfall over land. Jones et al. found that – with geographically more limited seeding - the occurrence of rainfall reduction over land via MCB did or did not occur dependent on the choice of seeding locations. Our own work on MCB, with larger seeding areas, gave results similar to those of Bala et al. So it is too sweeping and also misleading to say that SRM would cause droughts in the Sahel. Although designed to produce global effects MCB, in principle, could also be used to address much smaller-scale issues, such as hurricane weakening and coral reef preservation: and could perhaps prove helpful regarding the prevention of polar sea-ice loss Best Wishes, John. John Latham Address: P.O. Box 3000,MMM,NCAR,Boulder,CO 80307-3000 Email: lat...@ucar.edu or john.l...@manchester.ac.uk Tel: (US-Work) 303-497-8182 or (US-Home) 303-444-2429 or (US-Cell) 303-882-0724 or (UK) 01928-730-002 http://www.mmm.ucar.edu/people/latham ________________________________________ From: geoengi...@googlegroups.com [geoengi...@googlegroups.com] on behalf of O Morton [omeco...@gmail.com] Sent: 02 April 2013 14:53 To: geoengi...@googlegroups.com Subject: [geo] SRM and droughts in the Sahel Asymmetric forcing from stratospheric aerosols impacts Sahelian rainfall * Jim M. Haywood<http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1857.html#auth-1>, * Andy Jones<http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1857.html#auth-2>, * Nicolas Bellouin<http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1857.html#auth-3> * & David Stephenson<http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1857.html#auth-4> Nature Climate Change (2013) doi:10.1038/nclimate1857 Received 23 October 2012 Accepted 22 February 2013 Published online 31 March 2013 Article tools The Sahelian drought of the 1970s–1990s was one of the largest humanitarian disasters of the past 50 years, causing up to 250,000 deaths and creating 10 million refugees1<http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1857.html#ref1>. It has been attributed to natural variability2<http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1857.html#ref2>, 3<http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1857.html#ref3>, 4<http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1857.html#ref4>, 5<http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1857.html#ref5>, over-grazing6<http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1857.html#ref6> and the impact of industrial emissions of sulphur dioxide7<http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1857.html#ref7>, 8<http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1857.html#ref8>. Each mechanism can influence the Atlantic sea surface temperature gradient, which is strongly coupled to Sahelian precipitation2<http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1857.html#ref2>, 3<http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1857.html#ref3>. We suggest that sporadic volcanic eruptions in the Northern Hemisphere also strongly influence this gradient and cause Sahelian drought. Using de-trended observations from 1900 to 2010, we show that three of the four driest Sahelian summers were preceded by substantial Northern Hemisphere volcanic eruptions. We use a state-of-the-art coupled global atmosphere–ocean model to simulate both episodic volcanic eruptions and geoengineering by continuous deliberate injection into the stratosphere. In either case, large asymmetric stratospheric aerosol loadings concentrated in the Northern Hemisphere are a harbinger of Sahelian drought whereas those concentrated in the Southern Hemisphere induce a greening of the Sahel. Further studies of the detailed regional impacts on the Sahel and other vulnerable areas are required to inform policymakers in developing careful consensual global governance before any practical solar radiation management geoengineering scheme is implemented. Full article at http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1857.html Blogpost by me at http://heliophage.wordpress.com/2013/03/31/climate-geoengineering-for-natural-disasters/ Extract: One implication is that climate geoengineering deployed in just the northern hemisphere looks like a very bad idea. Programmes in just the north have been considered and studied, in part because of the worries people have about something suddenly going wrong in the Arctic, something that needs “fixing” quickly. This research makes such approaches look dangerous. More interesting, and more novel, is the implication that geoengineering might be used to avert a Sahelian drought caused by a volcano. If the stratospheric sulphates released in a major northern eruption were promptly countered by a deliberate release of sulphates into the southern hemisphere, both hemispheres would cool. The ITCZ would stay put, and a drought might well be averted. For a major drought, that would be a big win. The drought in the 1980s, which followed on the 1982 eruption of El Chichon in Mexico, killed about a quarter of a million people and turned millions more into refugees. ... And if the Earth is left to its own devices, such droughts will happen again. Last century there were two eruptions that cooled the north and were followed by drought in the Sahel. The north is better endowed with volcanoes than the south, since the Pacific “ring of fire” is more a horseshoe of fire, with a gap in the south but a continuous arc in the north. The odds of at least one eruption in the Pinatubo-to-Krakatoa range somewhere of the Earth in this century are better than even. The chances of one happening in the north are obviously lower; but the odds are hardly long. If humans had had the technological wherewithal to stop the 1980s Sahel drought in its tracks, would people have wanted to use it? It seems likely that there would have been a constituency for it, not least in the Sahel. And many of the reasons people have for objecting to geoengineering as an inappropriate “technical fix” to man-made climate change might apply with rather less force if the technology was being used to forestall a natural disaster on a continental scale. -- 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 geoengineerin...@googlegroups.com. To post to this group, send email to geoengi...@googlegroups.com. Visit this group at http://groups.google.com/group/geoengineering?hl=en. For more options, visit https://groups.google.com/groups/opt_out. -- 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 geoengineering+unsubscr...@googlegroups.com. To post to this group, send email to geoengineering@googlegroups.com. Visit this group at http://groups.google.com/group/geoengineering?hl=en. For more options, visit https://groups.google.com/groups/opt_out. -- 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 geoengineering+unsubscr...@googlegroups.com. To post to this group, send email to geoengineering@googlegroups.com. Visit this group at http://groups.google.com/group/geoengineering?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
