Agri Kultuur December / Desember 2018 - Page 35

that existing aircraft could be modified to lift huge quantities of sulphur dioxide to great heights, and then release it. “Dozens of countries could fund such a programme, and the required technology is not particularly exotic.” “Turns out that is not so,” he said. “It would indeed take an entirely new plane design to do SAI under reasonable albeit entirely hypothetical parameters. No existing aircraft has the combination of altitude and payload capabilities required.” Political tensions But solar radiation management or SRM – the catch-all term for any plans to cool the world by dimming the sunlight, rather than reducing greenhouse gas emissions – remains politically fraught, and in any case an incomplete answer: it would, for instance, do nothing to slow the increasing acidification of the world’s oceans, and it could seriously affect rainfall patterns in so far unpredictable ways. Detailed design The scientists outlined a solution: it had the same weight as a large, narrow-bodied jet passenger aircraft. But to sustain level flight at 20kms, it needed roughly double the wing surface of such an airliner, and double the thrust, with four engines rather than two. “At the same time, its fuselage would be stubby and narrow, sized to accommodate a heavy but dense mass of molten sulphur rather than the large volume of space and air required for passengers,” Mr Smith said. They then calculated the rate at which such planes could be built, and the numbers needed to make a significant difference to global warming. Global projects on such a scale need international agreement, and the two authors rule out the possibility that any individual nation could hope to secretly operate such a high-flying programme, involving so many flights, without detection. But they do not see it as excessively costly. “Given the potential benefits of halving average projected increases to radiative forcing from a particular date onward, these numbers invoke the ‘incredible economics’ of solar geoengineering,” Dr Wagner said. AgriKultuur |AgriCulture The world has already warmed by 1°C in the last century. In Paris in 2015 the nations of almost the entire world agreed to try to contain global warming to 1.5°C if at all possible. And the world now has only about a dozen years to make this happen. “Why then set out a plan to implement solar radiation management from a date 15 years hence? This plan is a distraction that may well encourage weaker action on emissions reduction by governments in the hope they will no longer be necessary”, said Joanna Haigh, co-director of the Grantham Institute for Climate Change at Imperial College in the UK. “Previously, proponents of SRM have suggested that it be used to delay the onset of the inevitable warming arising from human greenhouse gas emissions. This paper, however, seems to suggest that the implementation should be ongoing. Forever?” – Climate News Network info@ 35