The UN Environment Programme’s 2025 Adaptation Gap Report estimated that developing countries could need $310 billion a year for climate adaptation by 2035 when costs are modelled from sector needs. The estimate rises to $365 billion when countries’ stated plans are extrapolated, the report said.
International public adaptation finance to developing countries was $26 billion in 2023, down from $28 billion in 2022. The difference between estimated needs and reported flows shows why resilience projects compete for grants, concessional loans and domestic budget funding.
The figures are estimates, not a bill payable in one year. Adaptation spending covers measures such as flood protection, water management and heat planning; the right mix depends on local risk. The photograph is an illustrative rooftop-solar image, not a project featured in the report.