Palm trees standing in a cyclone

Geoengineering could have devastating side effects, study warns

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A University of Exeter study suggests that artificially cooling regions of the planet to counter the effects of climate change could cause devastation in other parts of the world.

Geoengineering is the deliberate manipulation of the climate, mainly to reduce the impact of climate change in addition to reducing carbon emissions and adapting to large-scale change. This could include capturing huge amounts of carbon dioxide from the atmosphere through tree planting or artificial carbon storage, or blasting aerosols into the atmosphere to create a ‘global dimming’ effect.

The latter approach – stratospheric aerosol injection – essentially imitates volcanic eruptions. Aerosols are injected into the atmosphere, reflecting some solar radiation before it is able to heat the surface of the Earth.

Solar geoengineering has long been considered a risky approach to countering climate change, although its potential impacts are difficult to predict.

Now, a team at the University of Exeter have published a study in Nature Communications which suggests that targeting geoengineering in one hemisphere could have catastrophic effects in the other hemisphere, particularly in areas prone to storms or droughts.

The researchers used simulations with a coupled atmosphere-ocean model in order to study the effect of stratospheric aerosol injection in the northern hemisphere, where it has the potential to reduce tropical cyclone activity responsible for extreme weather. Extreme weather events such as Hurricane Katrina are associated with climate change and have become more frequent in recent years.

Filling the northern hemisphere with these aerosols, they found, could reduce the frequency of these cyclones, but also lead to the increased likelihood of drought in the Sahel, south of the Sahara desert. Their results suggest that solar geoengineering could have unpredictable and counterproductive effects which must be taken into consideration.

Based on their findings, the University of Exeter team has called on international policymakers to tightly regulate any large-scale, unilateral geoengineering programmes in order to minimise the risk of inducing extreme weather elsewhere.

“Our results confirm that regional solar geoengineering is a highly risky strategy which could simultaneously benefit one region to the detriment of another,” said Dr Anthony Jones, climate scientist and lead author of the study. “It is vital that policymakers take solar geoengineering seriously and act swiftly to install effective regulation.”

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