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Silicon Valley is trying to fix climate change with balloons. But will it work?

This is Everyday Science with Clare Wilson, a subscriber-only newsletter from i. If you’d like to get this direct to your inbox, every single week, you can sign up here.

Hello, and welcome back to Everyday Science.

One of the coolest things about sci-fi is that authors sometimes predict new technologies that eventually become reality – like when US author William Gibson wrote in the 1980s about the internet and people living in online worlds.

A novel by one of my favourite authors, Neal Stephenson, centres on a crazy scheme to tackle global warming by firing sulphur into the atmosphere, which acts like a planet-shielding sunscreen.

This book, called Termination Shock, could also turn out to be prophetic. Two mavericks in California have recently started doing something very similar, except they are using giant balloons to release sulphur dioxide high in the atmosphere.

The scheme has become a way for people to try to combat their own personal carbon emissions, with customers being told how much carbon the sulphur they have paid for is equivalent to. The cost of the sulphur cooling credits is relatively modest – £9 to have the same effect as removing one tonne of carbon dioxide from the air per year, although you would have to pay that amount every year, because the droplets do fall out of the atmosphere.

There has been a lot of publicity around the failure of “carbon offsetting” schemes, such as planting trees to reduce atmospheric carbon dioxide. Could the sulphur balloons be a different way for people to combat their personal carbon emissions?

The premise behind carbon offsetting is sound. We know the world is warming, largely due to fossil fuels leading to rising levels of carbon dioxide in the atmosphere, which traps the sun’s heat like the glass of a greenhouse.

Climate change denialists aside, most people would agree that something needs to change. As well as the world slowing its carbon dioxide emissions, we can also try to directly remove carbon dioxide in various ways.

Tree planting may be the best-known example. As trees grow, they lock carbon into their wood – but other measures include stopping trees from being felled and burned.

Because the amount of carbon stored by trees can be exactly calculated, carbon offsetting is now billed as an option for individuals who, for instance, want to take a flight without feeling any green guilt.

Carbon credits 

Many companies also now advertise that some of their products or services are carbon neutral. This means that they have calculated the amount of carbon generated by their product and have repaid their debt to the planet by buying the same amount of “carbon credits”, with one credit equalling one tonne of carbon dioxide removed from the atmosphere.

Such products often aren’t much dearer than the same goods that lack the green seal of approval. Some airlines let you offset your flight at the time of purchase, with short-haul European flights only costing about £10 to offset. It sounds almost too good to be true.

Well, guess what – it is.

In recent years it has emerged that many carbon offsetting firms have been taking people’s money for schemes that are doing no good at all. This month, a huge analysis covering a fifth of the carbon credits ever issued, found that less than 16 per cent had achieved real carbon reductions. It was published in the journal Nature Communications.

“We’ve seen a whole gamut of fraud,” said offsetting expert Dr Injy Johnstone at the University of Oxford. “It’s something that works on paper but never in practice really.”

The chief problem is that it is almost impossible for carbon credit purchasers – whether individuals, companies or even governments – to know the claimed offsetting measures have really happened.

Offsetting firms use tricks like counting the same newly planted trees multiple times, or claim to have saved trees from being chopped down that weren’t really in danger. “There’s been very lax oversight,” said Dr Johnstone.

Sulphur strategy 

Is it time to consider radical new options, like sulphur balloons? The scheme’s developers are two Silicon Valley entrepreneurs called Luke Iseman and Andrew Song. While they are not trained scientists, nor are they affiliated with a university, their actions are based on some sound science.

The idea is that sulphur dioxide high in the atmosphere reacts with water to form a haze of tiny droplets of sulphuric acid, which reflects sunlight. Sulphur dioxide belched into the atmosphere by volcanic eruptions is known to have a measurable cooling effect on the climate – although it is temporary, as the droplets fall back to earth within a year or two.

In fact, several other groups have investigated similar schemes using different sulphur delivery methods, although none have so far got off the ground.

That doesn’t mean climate scientists are all in favour of the sulphur balloon project though. Complaints include that it could have unforeseen consequences, and that the team’s efforts are at too small a scale to have any measurable effect on the climate. Iseman said that because the droplets’ effect is temporary, any unwanted effects would be short-lived too.

A broader criticism is that such efforts at “geoengineering” should only happen after extensive testing and with agreement from the world’s scientific community.

Iseman says the climate crisis is too serious to wait for a global consensus. “As soon as we know directionality [of an intervention], that’s when we should take action,” he says. “Everyone agrees sulphur dioxide creates cooling.”

At the moment, the two sides are at an impasse. Iseman’s company, called Make Sunsets, seems to be acting perfectly legally, as the pair release their balloons from their own land. People who accept their arguments are going ahead with buying the novel “cooling credits”, and research continues on what the effects might be.

People who want to reduce their carbon emissions do not have just a binary choice between traditional carbon offsetting schemes and the sulphur balloon scheme, though, said Dr Johnstone.

While it might not be as easy as ticking a box when you buy a flight online, other options include directly investing in more mainstream (but less known) offsetting options, like alternative energy research or carbon capture and storage projects, which lock carbon away underground.

In fact, a few firms let you buy carbon offsetting credits specifically for such carbon storage projects. However, these tend to be much more expensive – sometimes one hundred times more – than those from the “traditional” offsetting firms, tonne for tonne of carbon, said Marta Krupinska, CEO of Cur8, a carbon removals firm. “If something is too cheap to be true, it’s too cheap to be good,” she said.

Dr Johnstone’s team at Oxford has produced a guide for effective carbon offsetting here, which also advises people to go for more expensive carbon storage projects.

Perhaps surprisingly for a carbon offsetting scientist, Dr Johnstone does not believe it should be the primary focus of people trying to do their bit to save the planet. “The causes of climate change are beyond the vast majority of individuals in their day-to-day consumer choices,” she said.

“The governments that we vote in can have the biggest impact. I think that there are no easy answers, but the best thing is to stop pretending that there is.”

Other things I’ve written recently 

Some experts say that the rising rates of  depression and anxiety seen in children and young people could be fuelled by some of the very activities that are supposed to tackle them – mental health awareness campaigns.

I’m reading 

Thinking about Termination Shock made me reread another novel by Neal Stephenson: Fall, or, Dodge in Hell, which must go down as one of my all-time favourite sci-fi books.

But I really, really, hope that this particular novel is not prescient about future events. Its depiction of people uploading their brains to virtual worlds after death is enough to put anyone off that idea.

This is Everyday Science with Clare Wilson, a subscriber-only newsletter from i. If you’d like to get this direct to your inbox, every single week, you can sign up here.

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