Authoritarian rulers fend off revolutions by stimulating the economy. However, expanding the economy can also increase environmental pollution. If citizens value clean air and water, worsening pollution has the potential to galvanize large segments of the society against the regime—which increases the risk of a revolution. While the literature has documented how concerns over the environment upend politics in democracies, we know relatively little about the effects of these concerns in authoritarian regimes. We analyze environmental pollution as an overlooked threat to authoritarian rulers. Using unique data from Communist East Germany and exploiting variation in thermal inversions to instrument for pollution levels, we find that pollution causes both individual and collective expressions of regime dissatisfaction. Our findings suggest that rulers face a trade-off between growing the economy and worsening pollution.