Geoengineering: What Could Possibly Go Wrong?

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We’ve touched on some of geoengineering's potential downsides, but let’s examine these risks in more detail.

Alan Robock, a prominent climate scientist at Rutgers University, has conducted groundbreaking research on the effectiveness and potential dangers of geoengineering. In fact, he authored a piece, "20 Reasons Why Geoengineering May Be a Bad Idea", published in the Bulletin of the Atomic Scientists. Fear not; it isn't required reading, but if you are interested in this topic, I encourage you to read it! His work offers a thoughtful and critical examination of geoengineering’s promise and its significant risks.

Alan Robock testifying at a U.S. House of Representatives committee hearing on climate change.

Credit: Climate and Envirnomental Science at Rutgers

Robock primarily focuses on the effects of the stratospheric sulfate aerosol solar modification scheme. Remember, this is the idea that we put billions of tiny little aerosol mirrors in the atmosphere, increasing the Earth's albedo and reflecting some sunlight back to space to help cool us down. But this scheme is certainly not without pitfalls! Robuck outlines some of them as follows.

Effects on Regional Climate

Stratospheric sulfate aerosols wouldn’t offset global warming evenly. Some regions would cool, while others could experience warming. Shifts in atmospheric circulation would result, likely leading to drying across many continental areas, with significant implications for water resources and agriculture.

Ozone Depletion

Injecting sulfate aerosols into the stratosphere could accelerate ozone-depleting chemical reactions, worsening the damage to the ozone layer and exposing the Earth to more harmful ultraviolet radiation.

Unintentional Warming

Sulfate aerosols in the lower stratosphere might sink into the upper troposphere and seed cirrus clouds, which could have a net warming effect. Cirrus clouds trap more heat than they reflect, potentially counteracting the cooling effects of the aerosols.

Reduced Solar Power Availability

Any strategy that reduces the amount of solar radiation reaching the Earth’s surface, whether through aerosols, mirrors, or cloud seeding, would diminish the efficiency of solar energy—a vital renewable resource.

Risk of Sudden Climate Change

If geoengineering efforts are abruptly halted—due to war, economic crises, or sabotage—the greenhouse warming masked by the geoengineering would resurface quickly. This sudden warming and the associated shifts in wind and precipitation patterns could be catastrophic for ecosystems and human societies.

Dependence on Geoengineering

Geoengineering could act as a “crutch,” enabling continued carbon emissions while avoiding immediate warming. However, this dependence would lock us into perpetual geoengineering. As CO₂ levels rise, the interventions would need to grow increasingly extreme, leaving us with no option to reverse course without facing dire consequences.

Ocean Acidification

Geoengineering schemes like sulfate aerosols do nothing to address ocean acidification, often called the “other CO₂ problem.” Without mitigating atmospheric CO₂ levels directly, the increasing acidity of oceans will continue to pose grave threats to marine ecosystems and biodiversity.

Unintended Consequences

The Earth system is extraordinarily complex, and our understanding remains incomplete. Tampering with it could lead to unexpected outcomes, many of which are unlikely to work in our favor. These unintended consequences pose a major ethical and practical challenge to any geoengineering approach.