Stratospheric Aerosol Injection

SAI is a proposed form of Solar Radiation Modification (SRM). It would use reflective aerosol particles in the stratosphere to redirect a small fraction of incoming sunlight back to space. In broad radiative terms, an SRM program would need to reflect only a very small fraction of incoming sunlight, roughly 0.2% to 0.3%, to stop additional warming from today.

CCI builds on fundamental research by climate scientists and examines potential next steps through a systems-engineering lens. Our goal is to evaluate not only whether SRM concepts are scientifically plausible, but whether they could be operationally feasible, governable, and safe enough to merit further consideration. This requires studying deployment constraints, failure modes, safety margins, monitoring needs, and real-world limits that laboratory research alone cannot fully answer.

Skypipe is a potentially game-changing innovation for SAI delivery. The concept originated from CCI trade studies aimed at identifying breakthrough technologies for mitigating worst-case warming scenarios: an actual pipeline from the ground to the stratosphere, composed of multiple textile tubes with air pumped upward through them. Aerosol particles can be entrained in that airflow for delivery to the stratosphere, while viscous drag from the upward-flowing air offsets the weight of the textile — so the tube effectively flies using internal aerodynamics.

CCI has been analyzing the technical feasibility of the Skypipe concept since January 2024. Our physics-based computer models show the concept is feasible, and potentially a vast improvement over aircraft-based delivery approaches.

• Systems engineering evaluation of SAI deployment concepts
• Technical barrier identification and characterization
• Risk and uncertainty quantification
• Monitoring and verification method development
• Input to governance framework development