Chalk dust? An issue? In these days of online whiteboards?

Well, yes, if you’re concerned – as we should all be – that, globally, we take the right approach when it comes to combating the climate crisis. It turns out that one extreme idea, to send tonnes of chalk dust, chemically known as calcium carbonate, up into the atmosphere, is due to have the first test run of some of its technology this year. The Stratospheric Controlled Peturbation Experiment plan, as it is called, which is financially backed by Bill Gates amongst others, is set to trial not the release of the dust itself but the mechanism of getting it up there, by balloon, in Sweden.

That’s dystopian sci-fi, not reality?

No, it’s real – and even the project director, Frank Keutsch, has called the need for this scale of geo-engineering – a method of dimming the light from the sun – “terrifying”. Keutsch says that the strategy would only be deployed in desperation to stop parts of the planet becoming uninhabitable.

Wouldn’t it be better just to cut our emissions?

Professor David Keith, one of the leaders of the experiment, said that the technique was not “an alternative, a substitute, to cutting emissions”. He argued that investigating the risks of such a method is necessary so that the next generation can make an informed decision. “It doesn’t guarantee they’ll make the right decision,” he said. “But, in my view, we have a duty to provide them with that information so they can make those decisions in the face of really horrific climate risks.”

Why are we even considering it?

Because there’s enough fear and scepticism around whether we are going to be able to reduce greenhouse gases emissions enough and to make these projects seem worth considering. And also because some people prefer a big technology fix to the idea that we might have to substantially change the way we live and operate across the globe.

What are the negatives?

Sir David King, a former chief scientific adviser to the UK Government, has said that such techniques for dimming the sun could have disastrous effects for weather systems.

Also, even if it did work, some scientists point out, it’s not an actual solution. Stuart Haszeldine, professor of carbon capture and storage at the University of Edinburgh, observed: “It would cool the planet by reflecting solar radiation but once you’re on to that, it’s like taking heroin – you’ve got to carry on doing the drug to keep on having the effect.”

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Sounds like more of a warning that things are going seriously wrong than an answer.

Exactly. The chalk dust plan tells us it’s time to get serious about cutting emissions so the next generation never has to consider this. With COP26 coming up, now is the time to renew focus on cutting greenhouse gases as rapidly as possible and pushing through a just transition to a greener future.