Trial aims to hose down warming climate

A team of scientists and engineers will in October pump water through a high-pressure hose suspended from a helium balloon 1km above a disused airfield in Norfolk in an unlikely bid to develop a technological solution to combating climate change.

The test at Sculthorpe will be Britain’s first experiment in the controversial field of geoengineering – counteracting global warming by deliberately cooling the climate.

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The team launched the £1.6m Spice (Stratospheric Particle Injection for Climate Engineering) project at the British Science Festival in Bradford on Tuesday.

“The project itself is not carrying out geoengineering, just investigating the feasibility of doing so,” said Matt Watson of Bristol University, Spice leader.

Even so, the experiment was condemned as a “climate technofix” by ETC, an environmental group opposed on principle to geoengineering, on the grounds that it distracts from the drive to cut carbon emissions and its effects are unpredictable.

“No form of geoengineering is a replacement for reducing carbon dioxide emissions,” Dr Watson insisted. “We hope that by carrying out this research we will start to shed light on some of the uncertainties surrounding this controversial subject, and encourage mature and wide-ranging debate that will help inform any future research and decision-making.”

The Sculthorpe experiment will assess the behaviour of hose and balloon in various weather conditions. It is designed to test the feasibility of injecting particles into the stratosphere 20km high, where they would make a real difference to the climate.

The approach – known as global radiation management – simulates the effect of a large volcanic eruption such as Mount Pinatubo in the Philippines in 1991, which cooled the Earth by 0.5C for two years by reflecting some incoming solar radiation back into space.

Although the Sculthorpe test will be pumping water droplets into the sky, any operational global system would probably not release water but an aerosol of sulphate particles like a volcano.

Part of the Spice project will look for the best material to inject into the stratosphere, combining excellent solar radiation scattering with minimal side-effects on weather, ecosystems and health.

A full-scale global cooling system would cost more than £5bn and take two decades to develop and install, said Hugh Hunt of Cambridge university, another team member. It would require 10 to 20 gigantic balloons, each the size of Wembley stadium, attached to ships distributed around the world’s oceans and pumping a total of 10m tonnes a year of material into the stratosphere.

Other forms of geoengineering have been proposed to remove carbon dioxide from the atmosphere, for example by fertilising the oceans to stimulate the growth of marine organisms.

“But if there was a dire climate emergency [with runaway global warming, in 20 years’ time] solar radiation management is the only thing we could do fast enough,” said Dr Watson.