Today Norfolk, tomorrow the world – geo-engineering technology on test
Scientists are to spray tap water from a helium balloon tethered a kilometre above north Norfolk later this year. They aim to test the technology of ‘geo-engineering,’ which may be used to reduce global temperatures in future decades.
The SPICE project (Stratospheric Particle Injection for Climate Engineering) is investigating the technical feasibility of injecting particles into the upper atmosphere at about 20 km to reflect radiation from the Sun back into space. The particles could lower global temperatures by as much as 2 degrees Celsius. .
The project, based at Cambridge, Oxford, Bristol and Edinburgh universities and involving Marshall Aerospace and the Met Office, is partly inspired by observations of what happened after the huge volcanic eruption of Mount Pinatubo in the Philippines in June 1991. This injected 10-20 million tonnes of sulphate particles into the upper atmosphere, lowering global temperatures for several years afterwards.
Dr Hugh Hunt from Cambridge University is leading the engineering, and described some of the challenges of pumping liquid through a hose 20 km long to a balloon tethered in the stratosphere at twice the cruising height of a commercial airliner. The liquid would have to be pumped from the surface at 6,000 Bar, about 50 times more than a pressure washer. Nobody has ever produced a pipe long enough or strong enough, and the balloon could be as long as Wembley Stadium. There is also uncertainty over the dynamic effects of wind and weight forces on the system. However, Dr Hunt likened the challenges to the Apollo mission – all the technologies needed were ‘nearly there’ and it was partly a matter of believing it was possible.
One major uncertainty is what chemical to use. It should ideally be highly reflective, with particles about 0.1 micrometre in diameter, and would have no chemical impact on the stratosphere or when it eventually fell to the Earth’s surface. However, the researchers point out that the quantities involved would be very small. The project is investigating different types of particle in the laboratory to decide which might be used in full-scale operation.
Another issue is how the cooling might be distributed around the globe. About 20 balloons might be used. They might not negate the effects of global warming in specific places even if they reduced global average temperature. The team is using climate models to predict the effects of different injection strategies.
Perhaps surprisingly, the scientists estimate that the scale and cost of full deployment could be modest – around 10 to 20 balloons globally at a cost of £5 billion, each balloon delivering at one tenth the flow of a garden hose. Dr Hunt pointed out that this sum is comparable to five nuclear power stations.
The team admits that the legal and ethical issues are “huge” and that world nations would never all agree to deployment unless there was a “dire emergency” with warming, but the study was needed in order to be able to pose the question. Marshall Engineering is working on some of the safety issues involved and is also experienced in flight-testing novel aircraft.
Speaking at the Science Festival in Bradford, volcanologist Dr Matt Watson, a leader of the project, emphasised that no form of geo-engineering was a substitute for reducing emissions of greenhouse gases and stressed that efforts to cut emissions are the true priority.
The SPICE project (Stratospheric Particle Injection for Climate Engineering) is investigating the technical feasibility of injecting particles into the upper atmosphere at about 20 km to reflect radiation from the Sun back into space. The particles could lower global temperatures by as much as 2 degrees Celsius. .
The project, based at Cambridge, Oxford, Bristol and Edinburgh universities and involving Marshall Aerospace and the Met Office, is partly inspired by observations of what happened after the huge volcanic eruption of Mount Pinatubo in the Philippines in June 1991. This injected 10-20 million tonnes of sulphate particles into the upper atmosphere, lowering global temperatures for several years afterwards.
Dr Hugh Hunt from Cambridge University is leading the engineering, and described some of the challenges of pumping liquid through a hose 20 km long to a balloon tethered in the stratosphere at twice the cruising height of a commercial airliner. The liquid would have to be pumped from the surface at 6,000 Bar, about 50 times more than a pressure washer. Nobody has ever produced a pipe long enough or strong enough, and the balloon could be as long as Wembley Stadium. There is also uncertainty over the dynamic effects of wind and weight forces on the system. However, Dr Hunt likened the challenges to the Apollo mission – all the technologies needed were ‘nearly there’ and it was partly a matter of believing it was possible.
One major uncertainty is what chemical to use. It should ideally be highly reflective, with particles about 0.1 micrometre in diameter, and would have no chemical impact on the stratosphere or when it eventually fell to the Earth’s surface. However, the researchers point out that the quantities involved would be very small. The project is investigating different types of particle in the laboratory to decide which might be used in full-scale operation.
Another issue is how the cooling might be distributed around the globe. About 20 balloons might be used. They might not negate the effects of global warming in specific places even if they reduced global average temperature. The team is using climate models to predict the effects of different injection strategies.
Perhaps surprisingly, the scientists estimate that the scale and cost of full deployment could be modest – around 10 to 20 balloons globally at a cost of £5 billion, each balloon delivering at one tenth the flow of a garden hose. Dr Hunt pointed out that this sum is comparable to five nuclear power stations.
The team admits that the legal and ethical issues are “huge” and that world nations would never all agree to deployment unless there was a “dire emergency” with warming, but the study was needed in order to be able to pose the question. Marshall Engineering is working on some of the safety issues involved and is also experienced in flight-testing novel aircraft.
Speaking at the Science Festival in Bradford, volcanologist Dr Matt Watson, a leader of the project, emphasised that no form of geo-engineering was a substitute for reducing emissions of greenhouse gases and stressed that efforts to cut emissions are the true priority.
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