Current approaches to identify the costs and benefits of adaptation are primarily quantitative, using top-down methodologies that may grossly underestimate the true costs. This policy brief argues that global policies require credible evidence from the local level. Given that a single generic adaptation model is unworkable, the policy brief introduces a new analytical costing framework – Participatory Social Return on Investment (PSROI) – which has been piloted successfully in subsistence farming communities in East and West Africa.

Although the Kenyan example is very specific, the PSROI framework provides an overall mechanism to cost any community-based adaptation initiative. Key lessons from the field site application are: community participation aids the design of adaptation interventions; information gaps can skew valuations; there is a need long-term thinking; and a better understanding of the diverse pressures on farmers is required. The brief recommends that the PSROI framework be adopted by policy-makers as an effective bottom-up approach that supports community participation and, by extension, climate change adaptation.