A series in the Guardian recently declared “it’s time to talk about geoengineering.” So let’s talk about it. And let us start with some simple truths about this cluster of techno-optimistic “quick fixes” which purport to somehow offset our slow progress towards zeroing out planet-warming carbon emissions.

Solar geoengineering proposals – reducing sunlight – have received the most attention, but a host of desperate schemes have been proposed in an effort to “fix” the disruption of climate caused by the growing burden of carbon dioxide human activities add to the atmosphere.

Many threaten the most sensitive aspects of polar environments, extending even to wildly expensive proposals to dam the Bering strait. If implemented, geoengineering schemes would put Earth’s physical climate in a dangerously precarious state, and introduce a major new destabilizing technology to an already turbulent political climate.

The essential thing to understand is that carbon dioxide, once emitted, is only very slowly removed from the atmosphere. A sizable share of it will still be keeping Earth dangerously hot millennia from now.

Solar geoengineering proposals involve injection of substances whose effect, by contrast, decays in a matter of years. Some might think this is an advantage of solar geoengineering. We can turn it on and off quickly when the damage it is doing to our planet becomes clear, right? Wrong.

Recent analyses demonstrate that it would take as long as two decades to create the required infrastructure. By then we would completely reliant on maintaining it – a tall task in a dangerous world with global conflict. It would only temporarily mask the pent-up warming implicit in the ongoing buildup of carbon dioxide, and this pent-up warming would be released in a catastrophically rapid “termination shock” if circumstances force the cessation of solar geoengineering.

So solar geoengineering does not “buy time” for decarbonisation. The same can be said for other geoengineering schemes, which also require sustained maintenance over centuries to millennia. Five hundred years from now, the fabled Bering dam may crumble, but the carbon dioxide wreaking havoc on the climate system will still be there waiting.

A lot of unforeseen things can happen in a few decades let alone over centuries. Do we really want to play dice with the planet? Do we want to commit today’s and future generations to maintain these approaches without........

© The Guardian