burning wood or dung -- and where there would otherwise be pressure to build coal- fired power stations. RENEWABLES It would be hard to think of a more inspiring challenge for young engineers than devising clean energy systems for the world. But if this fails, and if it’s clear, 20 years from now, that our climate seems heading irreversibly into dangerous territory, there may then be a pressure for ‘panic measures’. GEOENGINEERING --- being fatalistic about continuing dependence on fossil fuels, but combating its effects by geoengineering. GEOENGINEERING (PICTURE) It’s feasible, for instance, to inject enough aerosols into the stratosphere to cool the world’s climate -- indeed what is scary is that this might be within the resources of a single nation, or even a single corporation. There could be unintended side- effects. Moreover, the warming would return with a vengeance if the countermeasures were ever discontinued; and other consequences of rising CO2 (especially the deleterious effects of ocean acidification) would be unchecked. Geoengineering would be a political nightmare: not all nations would want to adjust the thermostat the same way. Very elaborate climatic modelling would be needed in order to calculate the regional impacts of an artificial intervention. (The only beneficiaries would be lawyers. They’d have a bonanza if nations could litigate over bad weather!). It may be prudent to explore geoengineering techniques enough to clarify which options make sense, and perhaps damp down undue optimism about a technical ‘quick fix' of our climate. EARTH I think we should be evangelists for new technologies - without them the world can’t provide food, and sustainable energy, for an expanding .and more demanding population. But we need wisely-directed technology - advanced renewables are wise goals, geoengineering techniqoes probably aren't. But what about the other technologies that pervade our lives? Can we cope with their HOUSE_OVERSIGHT_026736