How to Dim the Sun, from Marketplace's How We Survive

The podcast introduces the concept of geoengineering as a controversial approach to combat climate change, specifically focusing on solar geoengineering, which involves dimming the sun to reduce global temperatures. Host Amy Scott travels to the Bay Area to explore how small-scale experiments, such as launching sulfur dioxide into the stratosphere, are being conducted by entrepreneurs Luke and Andrew from Make Sunsets. The episode aims to spark discussion about the risks, ethics, and geopolitical implications of manipulating Earth's natural systems to address climate issues.

This section explains the scientific basis of solar geoengineering, especially stratospheric aerosol injection, which replicates volcanic eruptions that temporarily cool the planet. It covers how sulfur dioxide reacts with water vapor in the atmosphere to form reflective aerosols and the potential for these particles to mitigate global warming. The discussion delves into the scale of sulfur needed, the cost-effectiveness, and the early attempts by Make Sunsets to release sulfur into the atmosphere. The science is presented as promising but laden with unknown risks, especially concerning climate and human health.

The episode discusses opposition from environmental activists like Gary Hughes, who highlight the lack of regulation and transparency in geoengineering projects. Concerns include the risks of untested technologies, potential damage to the ozone layer, and unintended regional climate effects. There's also skepticism about the motives of wealthy individuals and corporations, which may seek profit or power under the guise of climate solutions. The episode stresses that geoengineering could divert attention from reducing fossil fuel emissions and may have unpredictable societal consequences due to the lack of a global governing body.

The podcast references volcanic eruptions such as Mount Pinatubo to illustrate natural analogs of geoengineering and their complex impacts on climate and societies. It notes that volcanoes can cause unusual weather patterns, droughts, and even contribute to historical upheavals like the French Revolution. The piece emphasizes that geoengineering involves meddling with powerful natural forces, with potentially irreversible effects and significant uncertainty about regional and global feedbacks.

Small-scale geoengineering experiments, including those attempted by Make Sunsets, are scrutinized as symbolic rather than impactful. The risks of large-scale deployment include damaging the ozone layer, causing adverse health outcomes, and provoking geopolitical conflict. The episode discusses how even historical volcanic events, which serve as natural experiments, reveal the unpredictability and profound societal effects of climate interventions. The overall message underscores the importance of cautious, transparent research and the need for a global dialogue before any large-scale geoengineering efforts.