Sorry, Andrew, I seem to have thoughtlessly double threaded -- feel free to put my recent post into this thread if that is within your moderating remit...
On Monday, 1 April 2013 11:17:28 UTC+1, andrewjlockley wrote: > > Posters note: a discussion of the policy implications of this paper can be > found at > http://m.guardian.co.uk/environment/2013/mar/31/earth-cooling-schemes-global-signoff, > > pasted below. > > http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1857.html > > Asymmetric forcing from stratospheric aerosols impacts Sahelian rainfall > > Jim M. Haywood, Andy Jones, Nicolas Bellouin & David Stephenson > Nature Climate Change (2013) doi:10.1038/nclimate1857 > Received 23 October 2012 > Accepted 22 February 2013 > Published online 31 March 2013 > > 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 refugees. It has been attributed to natural > variability, over-grazing and the impact of industrial emissions of sulphur > dioxide. Each mechanism can influence the Atlantic sea surface temperature > gradient, which is strongly coupled to Sahelian precipitation. 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. > > Comment piece below, > http://m.guardian.co.uk/environment/2013/mar/31/earth-cooling-schemes-global-signoff > > Guardian, Sunday 31 March 2013 17.59 BST > AIan Sample, science correspondent > > Earth-cooling schemes need global sign-off, researchers say > > World's most vulnerable people need protection from huge and unintended > impacts of radical geoengineering projects. > > Controversial geoengineering projects that may be used to cool the planet > must be approved by world governments to reduce the danger of catastrophic > accidents, British scientists said.Met Office researchers have called for > global oversight of the radical schemes after studies showed they could > have huge and unintended impacts on some of the world's most vulnerable > people.The dangers arose in projects that cooled the planet unevenly. In > some cases these caused devastating droughts across Africa; in others they > increased rainfall in the region but left huge areas of Brazil parched."The > massive complexities associated with geoengineering, and the potential for > winners and losers, means that some form of global governance is > essential," said Jim Haywood at the Met Office's Hadley Centre in > Exeter.The warning builds on work by scientists and engineers to agree a > regulatory framework that would ban full-scale geoengineering projects, at > least temporarily, but allow smaller research projects to go > ahead.Geoengineering comes in many flavours, but among the more plausible > are "solar radiation management" (SRM) schemes that would spray huge > amounts of sun-reflecting particles high into the atmosphere to simulate > the cooling effects of volcanic eruptions.Volcanoes can blast millions of > tonnes of sulphate particles into the stratosphere, where they stay aloft > for years and cool the planet by reflecting some of the sun's energy back > out to space.In 2009, a Royal Society report warned that geoengineering was > not an alternative to cutting greenhouse gas emissions, but conceded the > technology might be needed in the event of a climate emergency.Writing in > the journal Nature Climate Change, Haywood and others show that moves to > cool the climate by spraying sulphate particles into the atmosphere could > go spectacularly wrong. They began by looking at the unexpected impacts of > volcanic eruptions.In 1912 and 1982, eruptions first at Katmai in Alaska > and then at El Chichón in Mexico blasted millions of tonnes of sulphate > into northern skies. These eruptions preceded major droughts in the Sahel > region of Africa. When the scientists recreated the eruptions in climate > models, rainfall across the Sahel all but stopped as moisture-carrying air > currents were pushed south.Having established a link between volcanic > eruptions in the northern hemisphere and droughts in Africa, the scientists > returned to their climate models to simulate SRM projects.The scientists > took a typical project that would inject 5m tonnes of sulphate into the > stratosphere every year from 2020 to 2070. That amount of sulphate injected > into the northern hemisphere caused severe droughts in Niger, Mali, Burkina > Faso, Senegal, Chad and Sudan, and an almost total loss of vegetation.The > same project had radically different consequences if run from the southern > hemisphere. Rather than drying the Sahel, cooling the southern hemisphere > brought rains to the Sahel and re-greened the region. But Africa's benefit > came at the cost of slashing rainfall in north-eastern Brazil.The > unintended consequences of SRM projects would probably be felt much farther > afield. "We have only scratched the surface in looking at the Sahel. If > hurricane frequencies changed, that could have an impact on the US," said > Haywood.Matthew Watson, who leads the Spice project at Bristol University, > said the study revealed the "dramatic consequences" of uninformed > geoengineering."This paper tells us there are consequences for our actions > whatever we do. There is no get-out-of-jail-free card," he told the > Guardian."Whatever we do is a compromise, and that compromise means there > will be winners and losers. That opens massive ethical questions: who gets > to decide how we even determine what is a good outcome for different > people?"How do you get a consensus with seven billion-plus stakeholders? If > there was a decision to do geoengineering tomorrow, it would be done by > white western men, and that isn't good," Watson said. > -- 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.
