The electoral fate of incumbent politicians depends heavily upon voters’ well-being. Might climate change – by amplifying threats to human well-being – cause incumbent democratic politicians and parties to lose office more frequently? Here I conduct the first-ever investigation of the relationship between temperature, electoral returns, and future climate change. Using data from over 1.5 billion votes in over 4,800 electoral contests held in 19 countries between 1925 and 2011, coupled with meteorological data, I show that increases in annual temperatures above 21 °C (70 °F) markedly decrease officeholders’ vote share. I combine these empirical estimates with an ensemble of climate models to project the impact of climate change on the fate of future officeholders. Resulting forecasts indicate that by 2099 climate change may reduce average incumbent party vote share across all nations in the sample, with the most acute worsening occurring in poorer countries. If realized, these predictions indicate that climate change could amplify future rates of democratic turnover by causing incumbent parties and their politicians to lose office with increasing frequency.