The current pace of emission cuts and carbon capture technology may not be sufficient to prevent the worst impacts of global warming. Stratospheric aerosol injection (SAI), the scattering of reflective particles into the middle atmosphere, could cool the surface by reflecting sunlight, mitigating losses of lives and livelihoods. However, SAI carries enormous physical uncertainties that must be investigated before the risks can be fully understood. The impacts of SAI depend on the latitude, altitude, and season of injection; therefore, SAI is not merely a "yes-or-no" problem, but also a design problem. By designing, simulating, and comparing different SAI strategies with a climate model, we can better understand how different strategies impact the Earth system differently; what climate objectives can be met with SAI; what objectives can or cannot be met simultaneously; and whether different strategies can meet the same objectives more effectively or efficiently, and why.