The Science Hour

As a series of UN climate reports have warned recently, drastic reductions in greenhouse gas emissions – a halving over the next decade – are needed if we are to keep global warming down to manageable levels. No sign of that happening. An emergency measure to buy time that’s sometimes discussed is solar geoengineering – creating an atmospheric sunscreen that reduces incoming solar heat. Sulphate compounds in volcanic gases or in industrial fumes attract water vapour to make a fine haze and have that effect. The difference would be starting a deliberate programme of injecting sulphate particles into the stratosphere. There are a host of arguments against it, including a revulsion against adding another pollutant to the atmosphere to offset the one, carbon dioxide, that’s giving us problems in the first place. Another objection, outlined this week, is that it could set back the global fight against malaria - a major killer in its own right. University of Cape Town ecologist Chris Trisos tells Roland Pease what