Geoengineering poses huge environmental threat, say scientists
An abrupt halt to climate engineering would have "devastating" consequences for the planet, scientists have warned.
Mimicking the effects of a volcanic eruption by spraying sulphur dioxide particles high in the atmosphere has been proposed as a last resort answer to climate change.
But if the operation had to stop suddenly for any reason the global impact could be disastrous, new research suggests.
The US team conducted computer simulations of a scenario in which large-scale geoengineering is used to achieve a moderate level of climate cooling.
It involved aircraft spraying five million tonnes of sulphur dioxide into the upper atmosphere every year from 2020 to 2070.
The strategy was calculated to lower global temperature by about 1C, roughly reversing the amount of warming that had occurred since the start of the Industrial Revolution.
However, a sudden halt to the spraying led to hugely accelerated climate change, with the planet heating up 10 times faster than it would have done had geoengineering not been deployed.
Lead scientist Professor Alan Robock, from Rutgers University, said: "Rapid warming after stopping geoengineering would be a huge threat to the natural environment and biodiversity.
"If geoengineering ever stopped abruptly, it would be devastating, so you would have to be sure that it could be stopped gradually, and it is easy to think of scenarios that would prevent that.
"Imagine large droughts or floods around the world that could be blamed on geoengineering, and demands that it stop. Can we ever risk that?"
Maintaining the sulphur dioxide cloud would mean aircraft having to fly continuously into the upper atmosphere, said Prof Robock. Without continual spraying, it would last only about a year.
Many animals and plants would not be able to survive in a rapidly warming world, said the researchers whose findings are reported in the journal Nature Ecology and Evolution.
"We really need to look in a lot more detail at the impact on specific organisms and how they might adapt if geoengineering stops suddenly," Prof Robock added.