Researchers launched a test flight of solar geoengineering in the UK last autumn

During the second flight in September 2022, the smaller payload balloon burst about 15 miles above Earth as it expanded amid decreasing atmospheric pressure, releasing about 400 grams of gas into the stratosphere. This may be the first time a measured gas payload has been verifiably released into the stratosphere as part of a geoengineering-related effort. Both balloons were released from a launch site in Buckinghamshire, southeast England.

There have, however, been other attempts to place sulfur dioxide in the stratosphere. Last April, the co-founder of a company called Make Sunsets says he tried to release it during a pair of rudimentary balloon flights from Mexico, as MIT Technology Review previously reported late last year. Whether it succeeded is also unclear, as the aircraft did not include equipment that could confirm where the balloons popped, said Luke Iseman, the startup’s chief executive.

The Make Sunsets effort has been widely condemned by geoengineering researchers, critics of the field, and the Mexican government, which has announced plans to ban or even halt any solar geoengineering experiments within the country. Among other issues, observers were concerned that the launches proceeded without prior notice or approval and because the company ultimately seeks to monetize such launches by selling “cooling credits”.

Lockley’s experiment was distinctive in several ways. It was not a commercial enterprise. The balloons were equipped with instruments that could track flight paths and monitor environmental conditions. They also included a number of safety features designed to prevent the balloons from landing while still filled with potentially dangerous gases. In addition, the group obtained flight permits and submitted what is known as a “notification to airmen” to aviation authorities, which ensures that aircraft pilots are aware of flight plans in the area.

Some observers have said that the amount of sulfur dioxide released during the UK project poses no real environmental risks. Indeed, commercial flights typically generate many times that.

“It’s a harmless piece of writing or a harmless experiment, in the immediate sense,” says Gernot Wagner, a climate economist at Columbia University and author of “Geoengineering: The Gamble.”

Public commitment

However, some remain concerned that the effort proceeded without broader public disclosures and commitment upfront.

Shuchi Talati, a fellow at American University who is creating a nonprofit focused on governance and equity issues in solar geoengineering, fears there is a growing disregard in the field for the importance of research governance. This refers to a set of rules and standards regarding the scientific merit and oversight of proposed experiments, as well as public transparency and engagement.

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