This chapter discusses Stratospheric Aerosol Injection (SAI), the process of injecting particles into the atmosphere to reflect sunlight, and its potential impact on Global Catastrophic Risk (GCR). The authors lay out the advantages and disadvantages of SAI, as it represents both a possible solution to global warming and a contributor to GCR in itself. This chapter therefore illustrates the necessity of rigorous analysis when it comes to climate change intervention technology, as the possible harms of such technology require extensive consideration. This chapter lays out a balanced argument, helping to determine if SAI is a beneficial policy response.