A HELIUM balloon the size of Wembley Stadium floating 20km overhead may provide a means of checking rising global temperatures.
A British research team is assessing the possibility of temporarily changing the atmosphere by spraying reflective particles into the upper atmosphere so as to reflect the sun’s radiation.
The balloon would be anchored to the ground and used to carry aloft a 20km-long pipe. This would spew out particles that would disperse into the stratosphere, performing like the ash blown out of a volcano to reduce the amount of solar energy reaching the earth’s surface.
Attempts to alter the planet or its atmosphere are referred to as “geoengineering”. The concept is contentious, however, given uncertainties about long-term consequences from interventions such as directly altering the atmosphere or the oceans.
Even so, a research consortium has been formed to examine the feasibility of using geoengineering in response to climate change-driven warming. Known as Spice (Stratospheric Particle Injection for Climate Engineering), the collaboration involves the universities of Bristol, Cambridge, Edinburgh and Oxford with Marshall Aerospace. Details of the Spice consortium were released yesterday in Bradford at the annual UK Festival of Science.
Geoengineering is not an attempt to circumvent action on climate change and could only be used in the most dire of circumstances, said project leader Dr Matt Watson from Bristol. “No form of geoengineering is a replacement for carbon dioxide emission reduction,” he said. “CO2 reduction is the way to go.”
He and other researchers believe, however, that scientists and the public should be aware of a geoengineering response to climate change, to reduce uncertainty and foster wider debate. To this end, the consortium applied for and received research funding worth £1.6 million (€1.8 million) to run a feasibility study to see if the massive engineering challenges could be overcome.
It would cost up to £5 billion to get a 200m-long balloon into the stratosphere and could take 20 years, according to Dr Hugh Hunt from Cambridge, whose three-year feasibility study is much more modest.
In October they plan to launch a much smaller balloon from a disused airport in Sculthorpe, East Anglia, that will carry a pressurised pipe up one kilometre.
This will serve as a test bed, allowing them to try different kinds of pipe and whether it could be used to spray out reflective particles, said design engineer Dr Kirsty Kuo. It will also allow them to test different tethering methods and study the aerodynamic properties of the pipe. Strong winds will buffet the pipe causing it to flex and the researchers want to understand how it will perform.
The research will split into three parts: finding the ideal particle, developing the delivery system and assessing environmental effects, Dr Watson said.
The idea is to have the kind of planetary impact as that caused by the 1991 Mount Pinatubo eruption in the Philippines. That discharge sent ash and sulphur dioxide as high as 30km, and caused global temperatures to drop by half a degree for two or three years.
The Spice consortium was not an advocate for geoengineering and the speakers described being cool on the idea.