6 November, 2026

A giant sunshade floating in space sounds like science fiction. But a recent report from the Planetary Sunshade Institute suggests the physics already make sense. But the bigger barriers are engineering and scale, which advances in space technology could address to make a sunshade feasible within 20–40 years.

Working out whether we can deploy solar radiation modification (SRM) may prove easier than agreeing whether we should. Many are unconvinced it’s such a bright idea, particularly given that the potential benefits and harms across borders: cooling could reduce some climate risks while affecting rainfall and ecosystems differently around the world. So, as research continues, there’s an urgent need to agree who gets to decide whether and how SRM is used.

We’ve seen climate technology become a market before. Greenhouse gas removal (GGR), which takes CO₂ from the atmosphere, has grown from research into an industry of start-ups, investors and corporate buyers. Companies can buy credits representing carbon removed to take responsibility for emissions they cannot yet eliminate.

SRM could take a similar path. Make Sunsets already sells $1 “Cooling Credits”, each representing a gram of sulphur dioxide released into the stratosphere, which it claims counteracts the warming from a tonne of CO₂ for a year.

But cooling is not removal. The GHGs remain in the atmosphere while SRM temporarily tackles one consequence. More importantly, the effects and risks of altering the climate cannot be neatly allocated to whoever bought the credit.

There may be good reasons to research SRM. But we shouldn’t let investment, credits, customers and growth create a market before governments agree whether, when and under whose authority it should ever be deployed. Sometimes responsible business means recognising that the market shouldn’t get to decide first. Just because we can, doesn’t always mean we should.

By Patrick Bapty