Slow progress reducing greenhouse gas emissions has increased attention on whether solar radiation management (SRM) geoengineering is a feasible and affordable tool to cool Earth, buying time for additional adaptation and mitigation efforts. Climate responses to several idealized SRM simulations have been studied in detail. In contrast, evaluating the plausibility of different SRM scenarios remains difficult and more collaboration between natural and social scientists is required. Moreover, the environmental and social impacts remain essentially unknown. We review evidence on impacts across stratospheric aerosol injection and marine cloud brightening technologies and scenarios. Rapid SRM termination, resulting in rapid climate change, would significantly increase threats to global biodiversity and ecosystems from climate change, especially in the tropics. In contrast, more measured use of SRM could reduce some climate risks for biodiversity but further research is needed. Agricultural impacts from geoengineering are predicted to be complicated. In general, cooling from SRM would benefit most crops but precipitation reductions could have negative impacts on rice and groundnuts in Asia. SRM strategies may also have impacts on human health from aerosol deposition at the surface.