The simplest and often first approach to applying laboratory results to natural environments is to measure reaction timescales. Here we define a timescale as the time taken for a given reaction sequence to build up steady state concentrations of desired products at a specified yield. Timescales measured in the lab will be determined by the physical conditions of the experiment. However, when applied to natural environments, the timescales will need to be adjusted to account for the specific conditions in the geochemical environment of interest. This is the approach taken by Rimmer et al. for UV-driven photochemistry. The utility of this approach is that it enables us to predict how a sequence of chemical reactions will play out in a natural environment. However, it is essential to acknowledge that these timescales will not exhibit straightforward relationships if the chemistry in the system is complex.