Sustainability
Artificial darkening of the sun only partially effective
Geoengineering would not easily prevent the collapse of the West Antarctic Ice Sheet – an important climate tipping point. This is the conclusion of a study published by the University of Bern in August.
To darken the sun, a whole fleet of extremely high-flying airplanes would have to spread millions of tons of aerosols – suspended particles in a gas – in the stratosphere every year. This would require two to three times the amount released by the eruption of the Pinatubo volcano in 1991 – the second-largest volcanic eruption of the 20th century, as a result of which the global average temperature dropped by around 0.5 degrees Celsius for around a year.
How effective such an approach would be depends on how emissions develop: If emissions continue unabated, the collapse of the West Antarctic Ice Sheet could be delayed somewhat, but not prevented. In a medium emission scenario, however, it could prove to be an “effective tool” to slow or even prevent ice sheet collapse.
Thomas Stocker, professor of climate and environmental physics at the University of Bern and co-author of the study, says: “Geoengineering would be another global experiment and a potentially dangerous human intervention in the climate system, which should in any case be prevented according to Article 2 of the UN Framework Convention on Climate Change.”