Fake eruption could combat global warming
A scheme to dim the Sun by mimicking the impact of volcanic eruptions will move a step closer next year with the first experiment in the stratosphere.
Scientists hope to prove that spraying tiny particles 19km above Earth’s surface could reduce global warming, by reflecting some of the Sun’s rays back into space.
They believe this would replicate what happened naturally in 1991, when Mt Pinatubo erupted in the Philippines and spewed 20 million tonnes of sulphur dioxide into the stratosphere. This cooled the planet by about 0.5 degrees C for 18 months. That could be enough to prevent some of the worst effects of climate change, saving coral reefs and Arctic ice and protecting low-lying communities from floods.
Such proposals for manipulating the climate, known collectively as geoengineering, face fierce opposition from some scientists and environmental groups, who believe that they distract attention from the need to cut greenhouse gas emissions.
There are also fears that particle spraying could damage the ozone layer and disrupt rainfall patterns, causing droughts and famines in some regions.
The US$3 million (NZ$4.3m) ‘‘stratospheric controlled perturbation experiment’’ (Scopex), partly funded by Microsoft billionaire Bill Gates, is being planned by a team of scientists from Harvard University.
They hope to send a steerable balloon above the southwest US in the first half of 2019. It will release small plumes of calcium carbonate and measure how this scatters light and changes stratospheric chemistry. They will use the results to improve computer models used to predict the impact and risks of geoengineering.
David Keith, a member of the team, said there was no evidence that any region would be worse off from a modest solar geoengineering programme conducted evenly around the world.
A study by Harvard and Yale scientists found that spraying particles into the stratosphere would be a ‘‘remarkably inexpensive’’ way of cooling the planet, costing US$2b to $2.5b (NZ$2.9b to $3.6b) a year.