Geoengineering flights could put passengers near harmful sulphuric acid

geoengineering flights – A plan to cool the planet by injecting sulphur into the stratosphere could, in a future that researchers are now stress-testing, require aircraft routes over polar regions. That’s where some passenger flights already fly—raising the prospect that cabins could

The idea starts with a familiar physics problem: how to block some sunlight to slow global warming. But in one scenario now being examined, the cure could place passengers in the path of chemicals that are better known for reacting in the atmosphere—and irritating the human airway.

Commercial airliners could pass through clouds containing sulphuric acid if solar geoengineering schemes move forward. The widely discussed strategy is to inject sulphur into the stratosphere, aiming to mimic the cooling effects of major volcanic eruptions from decades and centuries past.

At current levels of aviation, there’s a hard constraint. Spreading those chemicals near the poles would mean reaching altitudes of about 20 kilometres. nearly twice the maximum altitude of today’s planes. And Earth is still on course for up to 3.7°C of warming by 2100. a figure that has helped push interest in these sun-blocking concepts.

So researchers have begun looking at a more practical engineering route: upgrading aircraft such as Boeing 777s or similar planes to deposit sun-reflecting compounds in the sky near the poles. The catch is where the stratosphere dips. Near the poles it can reach as low as 7 kilometres—an altitude height that overlaps with flight paths used for passenger journeys. including routes that link Asia to North America.

Alan Robock, at Rutgers University in New Jersey, put the human question bluntly. “If airplanes can get up there to spray the sulphur. that’s also where airplanes go for passenger flights. ” he said. “So I was wondering how much [sulphuric acid] passengers and flight crew would be breathing if they were flying through these clouds.”.

To explore that. previous studies simulated a deployment of 6 million tonnes of sulphur dioxide into the stratosphere—13 to 15 kilometres above the ground—near the North Pole between March and June. and an equivalent injection near the South Pole between September and December. Atmospheric models suggested that 12 million tonnes of total sulphur dioxide. spread into the stratosphere in that way. would be enough to cool the globe by 0.6 to 1.0°C.

Robock and his colleagues then used the resulting concentrations of sulphuric acid from those simulations to estimate what could reach a plane’s cabin. The modelling matters because geoengineering flights would not release chemicals in a single burst. They would spray sulphur in long. thin plumes that would take days or weeks to spread and scatter through the atmosphere.

In some instances. passenger aircraft could travel through areas where cabin concentrations come in at about 7 micrograms per cubic meter—lower than ground-level sulphur dioxide levels in many of the world’s largest cities. But the same analysis also points to routes that could cross regions where sulphuric acid levels drive above 50 micrograms per cubic metre. That is the threshold the European Union defines as being hazardous.

The health implications are tied to what these chemicals do to the body. Breathing sulphur dioxide can irritate the throat and inflame the lungs. At higher concentrations. it can trigger more severe respiratory issues. including a tightening of the airways that impairs people’s ability to breathe. Exposure to elevated sulphur has also been linked to an increased risk of stroke.

Even when concentrations aren’t high, the concern doesn’t disappear. The pollution can trigger asthma attacks, and the paper suggests the risks would be highest for pilots and flight attendants who routinely travel on those polar routes.

For all the seriousness, researchers also stress the timing. Wake Smith. of Harvard University. said that the sort of deployment discussed in the paper is “many decades away. if it ever happens.” He believes that extended lead time could give airlines and engineers room to upgrade air filters to handle the predicted loads of sulphur dioxide and sulphuric acid—and keep passengers safe.

Daniele Visioni. at Cornell University in New York state. described the effort as a gap-filling exercise rather than a final verdict. “It was a useful exercise to run because nobody had looked at this before,” he said. “And they’re interesting preliminary results, but definitely not anything that would be a dealbreaker. The risks clearly lie elsewhere.”.

solar geoengineering sulphuric acid sulphur dioxide stratosphere aviation safety polar flight routes Boeing 777 climate engineering atmospheric models European Union hazardous threshold asthma