Solar geoengineering is a set of proposed large-scale techniques designed to reduce global warming by increasing the amount of sunlight reflected away from Earth back into space. Also known as solar radiation modification, it is considered a potential complement to emissions reductions rather than a replacement.
The most studied method is stratospheric aerosol injection, which would place reflective particles in the upper atmosphere. Other approaches include marine cloud brightening to increase cloud reflectivity over oceans, or constructing mirrors in space. Climate models suggest these techniques could reduce warming and potentially prevent certain tipping points, though resulting conditions would differ from a climate that had never warmed. Regional effects and environmental risks remain poorly understood. The field raises substantial governance questions: relatively low costs mean a single nation could theoretically deploy these technologies unilaterally, yet no international framework currently exists to regulate research or implementation. Critics worry that focus on solar geoengineering might weaken political will to cut emissions. Interest has grown recently as warming continues and emissions reduction efforts progress slowly, spurring both scientific investigation and ethical debate.
