Sticky brown sludge everywhere: can sludge explain barriers to green behaviour?

Behavioural science has sought to promote pro-environmental behaviours including climate-friendly dietary change, and to reduce travel emissions and excessive wastes. Nevertheless, there is a debate about how effective behavioural interventions are, and in turn, about the real barriers to enduring pro-environmental behaviour change. In this context, we conceptualise brown sludge as multi-level impediment to pro-environmental behaviour change, which results in higher environmental costs shared by the broader society, rather than solely by the individual actor. We propose that brown sludge comprises an array of additional transaction costs, encompassing, but not restricted to, psychological, temporal, and uncertainty costs. Brown sludge can occur at the individual, social, institutional, and societal levels. Examples include confusing eco-information, delay and disinformation campaigns, and complicated systems and infrastructure leading to carbon lock-in.