If you start sulfate geoengineering to mitigate climate change, don't stop. Seriously

Science 2.0: Policy makers are in constant discussion about a range of climate change mitigation possibilities and among the least understood are geoengineering methods. The injection of sulfate particles into the atmosphere to reflect sunlight and curb the effects of global warming could pose a severe threat if not maintained indefinitely and also supported by strict reductions in greenhouse gas (GHG) emissions, write  University of Washington researchers in Environmental Research Letters.

They highlight the risks of large and spatially expansive temperature increases if solar radiation management (SRM) - whereby tiny sulfate-based aerosols are released into the upper atmosphere to reflect sunlight and cool the planet - is abruptly stopped once it has been implemented.

The technique has been shown to be economically and technically feasible; however, its efficacy depends on its continued maintenance, without interruption from technical faults, global cooperation breakdown or funding running dry.  And whether or not it will actually work or do more harm than good.

According to the study, global temperature increases could more than double if SRM is implemented for a multi-decadal period of time and then suddenly stopped, in relation to the temperature increases expected if SRM was not implemented at all.

The researchers used a global climate model to show that if an extreme emissions pathway—RCP8.5—is followed up until 2035, allowing temperatures to rise 1°C above the 1970–1999 mean, and then SRM is implemented for 25 years and suddenly stopped, global temperatures could increase by 4°C in the following decades...

The Chatsworth, Illinois train wreck of 1887, from Harper's Weekly