For animals with sex determination linked to developmental temperature, variation in climate impacts population persistence and creates dynamic evolutionary pressures. Sex ratios may vary across space and time, depending on the climate, yet many species also appear to exhibit behavioural or physiological plasticity that minimizes sex ratio biases. This plasticity may be selected for in response to viability selection or frequency-dependent selection on sex, and would aid in the short-term persistence of populations under climatic change. Therefore, understanding the mechanistic basis of genetic and environmental influences on sexual differentiation informs the evolutionary history of a species and its risk of extinction.