Connecting behaviour change to systems change: rethinking climate action in scientific societies.

Climate change is increasingly recognised as one of the greatest threats to public health, and scientific societies, like the International Society of Behavioral Nutrition and Physical Activity (ISBNPA), are rightly asking how they can contribute to meaningful action. Yet a fundamental question remains largely unanswered: how can individual action be connected to efforts to address systemic drivers? At its 2026 conference in Cádiz, Spain, ISBNPA asked presenters to declare the estimated carbon emissions from their travel to the conference. Well-intentioned as it is, viewed through a systems lens, such an intervention risks placing disproportionate emphasis on individual responsibility when it is not embedded within broader institutional and structural change. Here we see parallels with complex public health problems within ISBNPA's scientific scope, where individual behaviours are increasingly understood as shaped by commercial, political and environmental forces. Building on the ISBNPA Climate Action Committee's initiative to rethink conference travel and its 2026 commentary, we examine this issue through four systems science lenses - shifting the burden, the fundamental attribution error, pushing stones uphill and unintended consequences - and outline three opportunities to connect behaviour change to systems change within ISBNPA: conference paradigm, research priorities and collective advocacy.