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The Geoengineering Question

Solar radiation modification – reflecting some of the sun’s rays to cool the planet – has long been shunned as a fringe idea. But evaluating possible futures both with and without this science, and researching its risks and benefits, offers a safer path to sound climate policy than simply ignoring the idea.

UTRECHT – In late June, the European Commission signaled for the first time a willingness to engage with solar radiation modification (SRM), a controversial concept that encompasses methods – more theoretical than real – to cool the planet by reflecting some of the sun’s rays. Yet by declaring that it would support efforts to assess “the risks and uncertainties of climate interventions”like SRM, the Commission has chosen to focus solely on these technologies’ potential dangers rather than their feasibility or potential benefits.

A more balanced approach to research is crucial to determine whether SRM, also known as solar geoengineering, can be a useful tool in the fight against climate change. Once a fringe idea, the deliberate modification of the atmosphere – for example, by introducing reflective aerosols into the stratosphere or by brightening clouds – has gained traction as the catastrophic effects of global warming become more pronounced. Some studies suggest that SRM could help limit temperature increases until emission cuts and carbon-dioxide removal can reduce greenhouse-gas (GHG) concentrations.

Clearly, solar geoengineering comes with its own environmental and societal risks. There are concerns that such techniques could distract humanity from cutting GHG emissions – the root cause of global warming. Moreover, if implementing SRM ends up being relatively cheap, wealthy countries could deploy it unilaterally or through selective coalitions. In 2022, these legitimate concerns led over 400 scholars to call for an international “non-use agreement,” which aimed to prevent public funding of SRM research.