Technology & Innovation

Re-engineering Planet Earth

July 30, 2016

Global

July 30, 2016

Global
Our Editors

The Economist Intelligence Unit

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Climate change has prompted some scientists to give serious consideration to re-engineering the earth’s atmosphere. The risks are formidable.

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Science-fiction writers have long explored the concept of terraforming—using engineering techniques to turn inhospitable worlds, such as Venus or Mars, into habitable planets. Such is the crisis of climate change that scientists are seriously discussing terraforming, or using geoengineering techniques, here on earth to avoid its impact.

When it comes to climate, changing the course of history takes time. In 1987 the international community agreed to limit the use of chlorofluorocarbons (CFCs), organic compounds that were then commonly used in aerosols, after they were found to deplete the vital ozone layer in the earth’s outer atmosphere. Only this year could scientists confirm that the hole in the ozone layer is beginning to heal.  

The use of CFCs is small fry when compared to humanity’s addiction to fossil fuels. Many experts fear that, even with the most concerted effort imaginable, it will not be possible to reduce carbon emissions in time to avoid the calamitous effects of climate change. Some have therefore proposed that we take more direct action.

The term geoengineering covers a number of planetary-scale engineering techniques that could be employed either to reduce the effects of new weather patterns or to dissipate the heat that is trapped by atmospheric carbon dioxide (CO2).

Proposed techniques range from seeding the oceans with iron to encourage the growth of algae that trap carbon from the atmosphere, to sending mirrors into orbit to reflect sunlight away from earth. Some ideas are remarkably simple—using light-coloured roofing materials to reflect sunlight, for example. Others require massive engineering projects, such as spraying seawater thousands of meters into the sky to lighten the colour of the clouds themselves, thereby changing the reflectivity of the planet.

Geoengineering is not without controversy. The earth’s climate system is too complex to model effectively using contemporary methods. HP, an IT company, once noted that a computer powerful enough to run a predictive model of the planet’s climate would require so much energy, and produce so much heat, that it would be a climate risk in and of itself. Any geoengineering measure powerful enough to impact our climate could therefore have considerable, negative and unintended consequences.

Seeding clouds with iodine crystals to force rainfall over a city suffering from drought might appear at first to be a good idea. But forcing that rainfall could limit snow coverage on a mountain range half a continent away, in turn preventing summer-melt runoff from irrigating agricultural areas. The interconnectedness of the earth’s climate system means that ill thought-out measures could have disastrous effects.

Without a comprehensive model of the planet’s climate, geoengineering is, at best, guesswork. At the scale needed to alleviate climate change, it’s hard to extrapolate from experiments to the planetary-scale implementation that would be needed to make even the tiniest change to the world’s climate.

For the foreseeable future, therefore, geoengineering is likely to be a tool of last resort. If we have to do it, we’ll have to get it right the first time. Outside of the imagination of science-fiction writers, we don’t have any other planets to go to.

Do you think we should use geoengineering techniques to fight climate change? How soon might we be able to model the earth’s atmosphere well enough to manage it safely? Share your thoughts on , sponsored by Dassault Systèmes.

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