Gwynne Dyer: Geo-engineering takes off to cool Earth's surface

Scientists who are working on various concepts for “geo-engineering” the climate are almost comically eager to stress that they are not trying to come up with a substitute for reducing carbon dioxide emissions, the main cause of manmade global warming. They are just researching backup systems that we might need if the reductions don’t happen fast enough.

“It’s hard to imagine a situation except a dire emergency where this will be used, but in order to have that conversation sensibly, we need to provide some evidence-based research,” Dr. Matt Watson of Bristol University told the British Science Festival in Bradford last week. He is planning to test the feasibility of an “artificial volcano” that injects sulphur dioxide into the stratosphere, so where better to try it than in the pancake-flat county of Norfolk?

Interestingly, he has the implicit blessing of the British armed forces, which take the threat of climate change very seriously. His experiment will be carried out at Sculthorpe airfield, a bomber base during the Second World War and still an active Royal Air Force facility. The goal is to find out whether non-rigid balloons (blimps) could be used to spray sulphur dioxide particles into the air and cool the planet’s surface.

Why an “artificial volcano”? Nobel Prize-winning atmospheric chemist Paul Crutzen, who first suggested this method of cooling the planet five years ago, pointed out that big volcanic explosions inject millions of tonnes of sulphur dioxide into the stratosphere, where they remain on average for a couple of years. During that time, they reflect enough incoming sunlight to lower the temperature at the surface appreciably.

The Mount Pinatubo explosion in the Philippines in 1991 put enough sulphur dioxide in the upper atmosphere to lower the average global temperature by half a degree Celsius (almost one degree Fahrenheit) for two years. No mass extinction or global famine ensued, so we can tentatively assume that human beings could also put sulphur dioxide into the stratosphere without causing instant global disaster.

We cannot assume that there would be no negative side-effects, however, which is why some scientists have been urging that we carry out small-scale experiments to learn more about the process. They also want to investigate how we could put such a large volume of sulphate particles into the stratosphere, for the task might turn out to be too expensive or just impossible.

That is the goal of a three-year project called Stratospheric Particle Injection for Climate Engineering (Spice), which is being supported by the universities of Bristol, Cambridge, Edinburgh and Oxford. The first phase of the project involves testing a blimp that will lift a reinforced hosepipe to an altitude of one km. (one thousand yards) and spray water into the air.

It’s purely about delivery methods: will a balloon tethered to the ground be stable enough to support such a length of hose, or will it become uncontrollable in the wind? If it passes that test, then the long process begins of scaling up to a blimp big enough to support a 20-kilometre (12-mile) hose, for that is the height at which the sulphate particles must be dispersed in order to stay up for a long time.

A blimp big enough to do that would be the size of a football stadium, and the Spice researchers estimate that it would take about twenty of them, moored over the ocean, to cool the planet by two degrees C. It would cost, they think, as little as $7 billion or as much as $75 billion dollars, but even the latter sum would look affordable to a government in a panic—the kind of panic that would occur if the planet got two degrees C (3.5 degrees F) hotter.

This is the first time that a geo-engineering idea has moved out of the lab and into the real world, and it is bound to attract some very hostile attention. You still hear the argument that we should not even discuss geo-engineering techniques, for the knowledge that they might exist will lessen the pressure to cut carbon dioxide emissions quickly. But the cat is out of the bag, and the best we can do is to figure out whether they are really a viable option.

Nobody is claiming that geo-engineering measures are a substitute for reducing our greenhouse gas emissions. But for all the talk about cutting emissions, they are still increasing, and it is highly unlikely that we will turn that trend around in time to avoid passing through two degrees C hotter—after which the risk of uncontrollable, runaway warming gets very big.

The scientists who are investigating geo-engineering are not reckless. They are actually the cautious ones, who want to have some fall-back plan available in case all the promises of future emissions cuts do not come true, just like all the past promises of emissions cuts failed to come true. We will get our emissions down eventually, no doubt, but it would be nice not to have a climate catastrophe in the meantime.

Can geo-engineering avert catastrophe? Nobody really knows, and that’s the point. “It may turn out that this whole strategy is a bad strategy,” as Dr. Hugh Hunt of Cambridge University, who is leading the field test at Sculthorpe, told The Independent newspaper. “That’s what we’re trying to find out.”




Sep 21, 2011 at 2:06pm

This approach uncomfortably reminds me or efforts to mitigate the effects of introducing foreign species by introducing other foreign species. A very slippery slope indeed.


Sep 21, 2011 at 2:56pm

Why stop at a sulfur dioxide volcano?

Why not make the Real McCoy (containing gigatons of magma and white-hot ash) and have it rain down on 3 or 4 billion people, thereby solving the population and climate problems simultaneously?

Keep it simple, stupid.

Brad Arnold

Sep 21, 2011 at 4:11pm

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Still don’t believe me? It convinced the Swedish Skeptics Society:

LENR using nickel. Incredibly: Ni+H+K2CO3(heated under pressure)=Cu+lots of heat. Here is a detailed description of the device and formula from a US government contract:

Still don’t believe me? A major US corporation has bought the rights to sell the 1 megawatt Rossi E-Cat, and it will be announced late October in the US, with the unit hitting the market in November. How can any fossil fuel compete with such cheap energy (and clean to boot!).

By the way, here is a current survey of all the companies that are bringing LENR to commercialization:

Diana Bronson

Sep 22, 2011 at 9:12am

This experiment should not be allowed to go ahead, especially when international negotiations on the governance of geoengineering are ongoing, This does not respect the CBD moratorium negotiated last year. For more info see: or visit the campaign against such experiments at

petr aardvark

Sep 22, 2011 at 10:06am

James Lovelock said that sooner or later we are going to become planetary maintenance technicians. Though one suggestion would be to put sulphur dioxide into jet fuel and dispersing it with passenger jet planes which I would think is cheaper. With respect to whether or not it should be done, if the governments of say Vietnam or Bangladesh or any low lying countries decide to do it there is nothing the rest of the world can do about it. Regarding the last comment, it would be cool if cold fusion was true but somehow I doubt it.

William Gibbens

Sep 22, 2011 at 11:08am

Sadly, Mr. Dyer held out this approach in his recent book and had refined his "Cimate Change" Remedy pitch to an almost feve pitch opver the course of two talks about a year apart in Vancouver. It still makes good copy...

Russ Collins

Sep 25, 2011 at 9:29am

What about acid rain? That sulphur dioxide doesn't escape to space, does it? So it rains down slowly over a couple of years.

"Governments have made efforts since the 1970s to reduce the release of sulfur dioxide into the atmosphere with positive results."

Jason Macnair

Mar 22, 2012 at 5:34pm

Normally I agree with Gwynne, but this idea is madness. History is replete with human engineered "solutions" to problems that go wildly array and create more problems. We cannot predict what the consequences of this will be. In addition, the idea that you could accurately predict how much this plan would cool the planet is absolute folly, anyone who claims they could predict the "cooling" effect of such a plan is a bald-faced liar.