Could we cool the planet by copying volcanoes?

Mount Pinatubo erupts in 1991

In 1991, Mount Pinatubo in the Philippines erupted violently, causing what so many scientists and politicians are trying to achieve these days: a reduction in global temperatures. The second largest volcanic eruption of the 20^th century, Pinatubo threw approximately 20 billion tonnes of sulphur dioxide (SO₂) into the air. Afterwards, the SO₂ caused a proportion of the sun’s energy falling on the planet to be reflected back out into space. 1992 and 1993 were the two coolest years of the 1990s.

So, perhaps man could create a similar effect that would balance out any dangerous temperature rises. Or so suggests Stewart Brand, a biologist by training, and fountain of ideas, who I saw talk on Monday to promote his new book “Whole Earth Discipline”. Much of what Brand said addressed how to solve the problems that global warming will cause.

Brand would rather governments not step in and try to take charge of the response to global warming. However, he highlights the burning of coal for electricity as a big contributor to the greenhouse effect, and admits that governments will probably have to step in to cut back on this.

Likewise his other solutions – including increased uptake of nuclear power, wider acceptance of genetically-modified foods – need to be achieved on city-, country- or planet-wide scales. This is some way from what Simple Climate hopes to address – what any single individual can do. So, when this was the subject of the very last question of the evening even Brand, with his expertise, struggled.

Brand's new book

What he eventually advised was that each of us try and join in the “conversation”, about the issue. Whether we’re among those that he suggests take an almost religious, unshakeable, stand on the matter, either the believers, or the “denialists”. Or whether we’re among the group he calls “warmers”, people close to the scientific data that are convinced that man-made climate change is happening, which includes the vast majority of climatologists. And even the sceptics, those who question whether the climatologists have it right on scientific grounds and who Brand expects would continue to do so, even if the climatologist changed their minds. If everyone makes their voices heard, the right ideas and actions will emerge.

And on the matter of cooling the planet by copying volcanoes? Well, after seeing Brand I looked at a review paper from the prestigious science journal Nature in 1995 examining the effects of Pinatubo. It points out that as well as cooling the planet, the increase in atmospheric SO₂ attacked atmospheric ozone. With the world having just about successfully dealt with this one environmental threat – the hole in the ozone layer – do we want to literally open it up all over again? As Brand himself said on the matter: “More science needed”.

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