9 Jan 2014

Geoengineering could bring severe drought to the tropics

Reversing climate change via huge artificial volcanic eruptions could bring severe droughts to large regions of the tropics, according to new scientific research. The controversial idea of geoengineering – deliberately changing the Earth's climate – is being seriously discussed as a last-ditch way of avoiding dangerous global warming if efforts to slash greenhouse gas emissions fail.

An agricultural aircraft flies over Prachuab Khirikhan in a bid to seed clouds

But the new work shows that a leading contender – pumping sulphate particles into the stratosphere to block sunlight – could have side-effects just as serious as the effects of warming itself. Furthermore, the impacts would be different around the world, raising the prospect of conflicts between nations that might benefit and those suffering more damage. "There are a lot of issues regarding governance – who controls the thermostat – because the impacts of geoengineering will not be uniform everywhere," said Dr Andrew Charlton-Perez, at the University of Reading and a member of the research team.

The study, published in the journal Environmental Research Letters, is the first to convincingly model what happens to rainfall if sulphates were deployed on a huge scale. While the computer models showed that big temperature rises could be completely avoided, it also showed cuts in rain of up to one-third in South America, Asia and Africa. The consequent droughts would affect billions of people and also fragile tropical rainforests that act as a major store of carbon. "We would see changes happening so quickly that there would be little time for people to adapt," said Charlton-Perez.

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