US startup wants to inject sulfur into the atmosphere to cool down the Earth

In theory, it could mitigate the effects of global warming; but experts are wary.
Ameya Paleja
USA at night
USA at night


Make Sunsets, a California-based startup, released weather balloons that carried sulfur particles into the stratosphere which possibly burst there, releasing the chemical, MIT Technology Review reported. We do not know if this happened since the balloons did not carry any monitoring equipment with them.

Founded by Luke Iseman, previous director of hardware at Y Combinator, the attempts by the startup fall into the controversial area of solar geoengineering where particles are released into the atmosphere with an aim to reflect sunlight back into space to ease global warming. The field has largely been a thought experiment with no real consensus if the technology can help us fight climate change.

Make Sunsets, however, appears to have jumped the gun and released weather balloons without any regulatory approvals or oversights from scientific agencies or even before the company was incorporated. The rudimentary balloons were released from Baja California in Mexico in April, while Make Sunsets was formally incorporated only in October this year.

What were the balloon launches like?

Iseman told MIT Technology Review that the first two launches were much like science projects. Iseman put a few grams of sulfur dioxide in weather balloons and pumped them up with enough helium he assumed would take them to the stratosphere.

At that altitude, he expected the balloons to burst under pressure and release the sulfur particles that would reflect back the sunlight. With no monitoring equipment on these balloons, it is unclear what actually happened to the experiments and if they even reach the intended altitude.

However, that's not stopping him from his plan to sell $10 "cooling credits" for releasing one gram of sulfur in the stratosphere that he claims will offset the warming effect of one ton of carbon for one year. The startup has raised $750,000 in venture capital funding so far and also sold the credits to early investors.

Iseman is hopeful that future launches will carry higher payloads of sulfur as well as sensors and equipment to measure the impact of the method, which will be published. He firmly believes that the threat from climate change is so grave that radical interventions are needed now.

Not a good idea

Experts, however, disagree with the approach, which they say is fuelled by financial motives which might end up overselling benefits, downplaying risks, and selling services even when no longer required.

The credit system is also being questioned since the cooling effect cannot be quantified as of today and may not have any value on climate credit markets. Even the science of the approach is questionable since commercial flights emit 100 grams of sulfur per minute, experts pointed out.

Iseman claims that his company is working on the best modeling data available today and hopes to learn and collaborate with experts as it scales up its efforts which it intends to do safely but quickly.

Critics, however, told MIT Technology Review, that the company should have reached out to the geoengineering community and the general public before injecting sulfur into the atmosphere or selling cooling credits off its plans. It can now expect only a cold shoulder for its efforts.

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