Climate conundrumParticle injection into the stratosphere could mitigate effects of climate change

Published 16 July 2010

In what scientists describe as Plan D, or an insurance policy for the situation in which Earth hits a tipping point in climate change quickly, a 20-kilometer pipe — “garden hose to the sky” — would be deployed to spray a shield of sulphate particles into the stratosphere; the idea is to emulate the eruption of volcanoes which spew sulphur-rich gas that spread worldwide, blocking sunlight and lowering temperatures

A 20-kilometer pipe designed to spray a shield of sulphate particles into the stratosphere could be deployed to mitigate the potentially devastating effects of climate change. The team involved with the SPICE (Stratospheric Particle Injection for Climate Engineering) project has received £1.6 million from the U.K. Engineering and physical Sciences Research Council (EPSRC) to test the feasibility of constructing what some in the research community have referred to as a “garden hose to the sky.”

Principal investigator, Bristol University’s Matt Watson, told Siobhan Wagner that the idea is inspired by volcanoes and the way they can affect the climate after eruptions.

An extreme example took place in 1815 when a volcanic eruption on the Indonesian island of Sumbawa led to 1816 being known as the ‘”ear without summer.” The eruption from the volcano Tambora spewed out 400 million tons of sulphur-rich gas that spread worldwide, blocking sunlight and lowering temperatures.

Watson said the SPICE project is not looking to recreate a Tambora, but it will be relying on the same principle of using stratospheric particles to refract light and cool the Earth.

Their work will begin at the Rutherford Appleton Laboratory in Oxford, where the researchers will use lasers and molecular spectroscopy to choose the particles they want to use. According to Watson, the team is drawn to the use of sulphate because of its particular “shininess” to visible light. The team, however, will trial other particles including clays, salts and mineral oxides.

Whatever they choose, Watson said, will not matter unless they can get it into the stratosphere.

Wagner writes that the current proposal sees the construction of a 20-km Kevlar pipe tethered by one or more balloons. Cambridge University’s Hugh Hunt, who is leading the delivery systems portion of the project, will address the engineering challenges inherent in such an ambitious idea.

Hunt and his team of Ph.D. students will address material-science questions ranging from how the pipe will be manufactured to how it will withstand the extreme stresses and pressures when in use.

Watson said the team will be especially concerned with how the pipe and tethered balloon or balloons will behave in different types of weather systems. “If you’re going to loft a helium balloon to 20 kilometers you would need have to have a very good handle on what the wind is doing at these elevations.”

Watson said the base of the pipe will have to be especially reinforced because it