As the climate crisis intensifies, experiments to “cool the planet” by reflecting solar radiation proliferate. Without proper global and national regulation, they will worsen the crisis.

Deliberately reflecting sunlight into space to cool the planet—solar radiation modification (SRM)—is now under serious exploration/investigation as a solution to the climate crisis. In theory, firing sulfur droplets into the stratosphere, spraying salty water into clouds, or scattering glass over polar ice could slow global warming. But as these experiments involve risks at a planetary scale, we should proceed with abundant caution, communication and transparency, regulated by globally agreed standards. Instead, we see ethical and legal boundaries being crossed by unregulated experiments.