Recent debates about the concept of planetary boundaries recall longstanding concerns about whether ecological limits are compatible with ecological democracy.

The planetary boundaries framework defines values for key earth-system processes such as climate change and biodiversity that represent a “safe” distance from thresholds or levels that could endanger human well-being. Despite having a significant impact in policy debates, the framework has been criticized as implying an expert-driven approach to governing global environmental risks that lacks democratic legitimacy.

Drawing on research on deliberative democracy and the role of science in democratic societies, the article argues that planetary boundaries can be consistent with democratic decision-making. Iterative, dialogic processes to formulate planetary boundaries and negotiate planetary targets could form the basis of a democratically legitimate division of labour among experts, citizens and policy-makers in evaluating and responding to earth-system risks.

Crucial to this division of evaluative labour is opening up space for deliberative contestation about the value judgments inherent in collective responses to earth-system risks, while also safeguarding the ability of experts to warn others about risks they consider unacceptable.