Over the Northern Hemisphere's summer, the world's temperatures hovered near 1.5° C above pre-industrial temperatures, and the catastrophic weather events that ensued provided a preview of what might be expected to be the new normal before mid-century. And the warming won't stop there; currently, our current emissions trajectory is such that we will double that temperature increase by the time the century is out and continue beyond its end. All of this has led many people to argue that some form of geoengineering is necessary.