The latest fix for the climate crisis? Blasting a big umbrella into space

Launching a giant umbrella into space to shade Earth and stop global warming sounds like a concept that a small child might come up with in science class. “That’s a really interesting idea,” the teacher would say, before sending little Timothy off to draw aliens in the quiet corner so the other kids can concentrate. Now, though, against all odds, it seems like Timothy might actually have been onto something. Either that, or – facing rising temperatures, missing ice caps, and messed up wildlife – we’re increasingly willing to give anything a shot.

So here we are. The latest proposal for limiting the effects of global warming is, quite literally, to launch a massive umbrella into space. Technically, it’s a bit more complicated than that, but also... not really? In fact, the idea was allegedly sparked by regular parasols used to shade people from the sun in Hawaii, and was subsequently explored in a study published in Proceedings of the Natural Academy of Sciences. Find out more below.

István Szapudi, an astronomer at the University of Hawaii Institute for Astronomy, is credited with the bright idea to blast a big umbrella (OK, OK, a “tethered sun shield”) beyond our atmosphere to avert the climate crisis. “In Hawaii, many use an umbrella to block the sunlight as they walk about during the day,” he says in a statement. “I was thinking, could we do the same for Earth and thereby mitigate the impending catastrophe of climate change?”

Humans have accelerated global warming at unprecedented rates by releasing greenhouse gases like carbon dioxide into the atmosphere, which trap sunlight that should be bounced back into space. Most efforts to cool the planet aim to reduce the amount of greenhouse gases we release, but this one would involve blocking some of the sun’s rays from reaching Earth in the first place.

According to Szapudi, if the solar shield (AKA umbrella) was big enough and positioned correctly, it could block about 1.7 per cent of solar radiation from reaching Earth. That might not sound like much, but it’s enough to prevent temperatures reaching the disastrous levels that they’re currently projected to hit.

In theory, the umbrella would rest at the L1 Lagrange Point – a position between the sun and the Earth, where the gravitational pull of the two bodies would effectively keep it in place. There’s a problem, though. The umbrella would have to be huge and hardy to withstand the forces at L1, as well as a barrage of solar radiation. Right now, we don’t have any rockets capable of launching such an object.

This is where Szapudi’s research comes in. He found that tethering the shade to a passing asteroid – or other materials captured from space – could significantly reduce the mass of the shade. Of the 3.5 million tons that the whole contraption would need to weigh, only one per cent would be the shield itself, and that’s all that would need to be launched from Earth.

Well... not really. For one, it’s unclear if there would be any knock-on effects from blocking out a significant portion of sunlight. Plus, the weight of the parts that would have to be launched from Earth still adds up to around 35,000 tons, and today’s biggest rockets can only lift around 50 tons to low Earth orbit. Not good enough, Elon!

With innovations in space flight and the development of new, lighter materials to build the shade out of, though, Szapudi suggests it could be feasible within decades. With ecological breakdown looming, and studies warning of crucial tipping points on the horizon, this might not provide much hope. That said, it’s the first concept of its kind with any real potential.

The umbrella idea is an unusual and grandiose suggestion to combat the climate crisis, but it isn’t the only one. Other projects in the field of “solar geoengineering” (in other words, reducing global warming by blocking some of the sun’s rays) include pumping aerosols into the atmosphere to “edit” clouds and bounce sunlight back into space, which frankly sounds like a bad idea.

In late 2022, scientists also announced a new breakthrough in the development of nuclear fusion, which could one day be used to create an artificial “second sun” and drastically cut humanity’s carbon footprint. Is any of this actually going to work? Who knows. It might be a good idea to focus on what we can do on Earth already, insteading of just crossing our fingers and hoping we’re around long enough to find out.

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