Plan to cool planet could be disastrous

By Steve Connor

Geoengineering climate would in effect create another catastrophe, study finds.

Photo / Christine Cornege
Photo / Christine Cornege

A controversial proposal to cool the planet artificially by injecting tiny reflective particles into the upper atmosphere which block out sunlight would cause droughts and climate chaos in the poorest countries of the world, a study has found.

One of the more serious plans to "geoengineer" the global climate would in effect create another climate catastrophe that would result in misery for millions of people, according to a computer model of the plan.

Some climate researchers have suggested that mimicking the cooling effects of volcanic eruptions with massive injections of sulphate particles into the atmosphere may be necessary in an emergency if global temperatures and carbon dioxide levels continue to rise unabated.

It is known that the sulphate particles produced by volcanoes, which are relatively quickly washed out of the atmosphere, can reduce incoming solar radiation significantly.

However, a study by scientists at Reading University has found that the effect of a massive and continuous injection of sulphates into the air would be to alter the rainfall patterns over vast regions of the world, notably Africa, South America and Asia which could as a result be devastated by drought.

"We have shown that one of the leading candidates for geo-engineering could cause a new unintended side-effect over a large part of the planet," said Dr Andrew Charlton-Perez of the University of Reading, a co-author of the study published in the journal Environmental Research Letters.

"The risks from this kind of geo-engineering are huge. A reduction in tropical rainfall of 30 per cent would, for example, would dry out Indonesia so much that even the wettest years after a man-made intervention would be equal to drought conditions now," Charlton-Perez said.

"The ecosystems of the tropics are among the most fragile on Earth. We would see changes happening so quickly that there would be little time for people to adapt."

Volcanoes, such as the Mt Pinatubo eruption in 1991, can cool temperatures significantly for short periods, but to reverse the expected 4C rise in global temperatures would need large quantities of sulphate aerosols to be injected into the upper atmosphere over several years.

"To reduce global temperatures enough to counter effects of global warming would require a massive injection of aerosol - the small particles that reflect sunlight back into space. This would be equivalent to a volcanic eruption five times the size of that of Mt Pinatubo every year," said Dr Angus Ferraro of Exeter University.

Professor Ellie Highwood of University of Reading, a co-author of the study, said: "On the evidence of this research, stratospheric aerosol geo-engineering is not providing world leaders with any easy answers to the problem of climate change."

- Independent

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