Major volcanic eruptions are considered as natural analogues for stratospheric sulfate aerosol geoengineering that aims to cool the climate by increasing the burden of stratospheric sulfate aerosols. Volcanic eruptions produce a layer of sulfate aerosols that stays in the stratosphere for a couple of years, whereas geoengineering efforts would need to sustain the aerosol layer persistently to counteract CO 2 ‐induced warming. Here we use a climate model to compare climate changes in response to a volcano‐like pulse aerosol forcing and a geoengineering‐like sustained aerosol forcing. When producing similar amount of global mean cooling, the pulse aerosol forcing results in a much larger reduction in land temperature and land minus ocean temperature when compared to that induced by a sustained aerosol forcing. Also, both land precipitation and runoff decrease more in response to the pulse aerosol forcing. Spatial patterns of temperature and the hydrological cycle change also differ substantially between these two types of forcings. These differences in the climate response between the pulse forcing and sustained forcing clearly show that caution should be taken when using climate consequences of volcanic eruptions to directly infer climate responses to stratospheric aerosol geoengineering.