Coproduced assessments of climate change adaptation reveal equity challenges in locally led approaches.

Systematic assessments of climate change adaptation are critical for monitoring progress and planning effectively, but current approaches are limited in their scope, accuracy, and relevance to local contexts. Here, we present an improved approach using coproduction to quantitively assess adaptation based on local knowledge and priorities. This is applied to locally led adaptation (LLA) to flood risk in Tamale, Ghana, to provide the first quantitative assessments of this increasingly common adaptation practice. Through a multi-year process, including community marble distribution, focus groups, and household surveys, 11 LLA solutions were assessed. Assessments were based on adaptation success criteria that mattered most to local communities and included important considerations that are commonly missing from technical assessments, including multiple risk-reduction mechanisms, equity, sustainability, and co-impacts. Community-based and behavioural LLA solutions, such as collective action and tree planting, were deemed most effective, whilst structural and technical solutions were ranked lower. By integrating these assessments into a flood risk model, we show that LLA approaches significantly reduced flood risk overall but did not address existing inequalities. Our results showcase the potential of coproduction to increase the scope and robustness of adaptation assessments and highlight practical challenges of delivering on the LLA principles in real-world settings.