On paper, there’s not much to suggest that the experiment should be the first step towards humanity’s destruction. High over the New Mexico desert, a repurposed balloon similar to those used by Nasa will float to an altitude of about 20km and release a payload. Scientific balloons can lift up to 3,600kg – the weight of three small cars – but in this instance, the cargo will be minuscule by comparison: first, a small volume of water, then, on a later trip, sulphates. The goal? To increase the density of particles in the clouds below, making them more reflective and bouncing solar radiation back into space. In other words, to dim the sun. Proponents of the experiment suggest it might be the first step in developing technology that could save the lives of tens of millions. Its detractors, however, predict it could kill or displace just as many.
The experiment, known as Scopex (Stratospheric Controlled Perturbation Experiment) is being designed by scientists at Harvard and is awaiting review from an external advisory committee before it launches its first-phase $3 million (£2.3m) test. With financial backing from Bill Gates, it will be one of the first real-life experiments to emerge from the untested field of geoengineering – the sketchy science of deliberately interfering with the earth’s climate. Ever since it became apparent that perilously little action was being taken to reduce global carbon emissions, a growing number of scientists around the world have advocated opening the Pandora’s Box that is man-made climate intervention. And Harvard’s not the only institution getting involved; in March, Cambridge University announced a proposed Centre For Climate Repair, headed by the chief scientific advisor to three British governments, Professor Sir David King, to look into radical ways to blunt the now-inevitable climate catastrophe.
These solutions typically range from the noncontroversial (technically, reforestation counts as man-made climate intervention) to the radical – “greening the ocean” by dumping tonnes of iron filings, to spur the growth of phytoplankton, or sprinkling billions of silica beads over a Belgium-sized section of the Arctic, to make the ice more reflective. Somewhere in the middle of the spectrum falls solar radiation management (SRM, or cloud brightening), the Scopex approach, which might just be the most feasible.
By no means is there consensus on how brightening should, or could, be done. King opposes the release of stratospheric sulphates as anything but a last resort, because they might damage the tentative recovery of the ozone layer, but he is keener on a similar alternative: marine cloud brightening (MCB). First conceived by the physicist John Latham in the early noughties, MCB proposes spraying a super-fine mist of seawater into the air over the ocean to increase cloud density – a natural, cheaper and mobile alternative. Professor Stephen Salter of the University Of Edinburgh, who worked with Latham, estimates that for around £90m per annum, a fleet of autonomous “spray vessels” built to his design could sail across the oceans where needed, sucking saltwater out of the sea and spraying it skywards to increase cloud density. Kelly Wanser, whose NGO Silver Lining advocates for cloud brightening, claims that a total increase of one per cent brightness could offset 2C of warming. King, Salter and Wanser believe that the technology could buy the world the 30-odd years needed to go fully carbon neutral. “[It] could protect the coral reefs that are dying,” says Wanser. “It could protect forests and ecosystems and species that will otherwise be devastated by the heat.”
Despite the enthusiasm in the scientific community, Al Gore has called geoengineering “delusional in the extreme”. In 2010, the UN Convention On Biological Diversity announced a moratorium on all large-scale geoengineering experiments that could impact the environment.
Spearheading opposition to SRM is the ETC Group, a watchdog and pressure group that has released statements in the past denouncing geoengineering as “a techno-fix” for climate change. Its co-executive director, Jim Thomas, believes that talk of man-made intervention “is a political strategy to try to change the way in which the debates on climate change happen”. The point, he says, is not whether SRM might work – he thinks it would – but that it distracts from real efforts to reduce carbon emissions and the knock-on effects would harm the globe’s poorest, whether through chance or design.
What’s more, Thomas says, geoengineering has a history of military application dating back to the Vietnam War. He points to a massive project on the Tibetan Plateau named Sky River, which is being carried out by a Chinese aerospace contractor on behalf of the military and involves lighting thousands of industrial burners on contested territory to manipulate precipitation. At the moment, the geoengineering arms race is a metaphorical one between scientists, start-ups and philanthropists, but it’s not hard to see the military advantage of a technology that could cause a massive spike in rainfall, or indeed a targeted drought.
Proponents of cloud brightening plead realpolitik, arguing that humanity has no alternative but to test them. “We don’t know yet whether or not these things are possibilities,” Wanser says. “If we don’t look at them fairly soon, then we won’t have these options available.” King agrees: “We have already destroyed our environment. We need these new technologies or, frankly, we are cooked.”
+ Dry run
During the 2008 Olympics, the Chinese government used a similar technique to cloud brightening to “seed” clouds with silver iodide, causing them to burst before they could rain on the Olympic Village.
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