In its Adaptation Gap Report 2025, the agency warns that a “yawning gap” in finance is “putting lives, livelihoods and entire economies at risk”.
The $310bn figure is based on modelled costs, however, when basing estimates on needs expressed in nationally determined contributions (NDCs) and national adaptation plans, this rises to $365bn.
Public adaptation finance flows to developing countries were $26bn in 2023, down from $28bn the previous year, leaving a potential annual gap of up to $339bn.
The report came shortly after the record-setting Hurricane Melissa tore through Jamaica, Haiti and Cuba, leaving at least 34 people dead. Researchers at Imperial College London believe that human-induced climate change made the hurricane four times more likely.
UN secretary-general António Guterres said that the adaptation finance gap is “leaving the world’s most vulnerable exposed to rising seas, deadly storms, and searing heat.”
“Adaptation is not a cost – it is a lifeline,” he continued. “Closing the adaptation gap is how we protect lives, deliver climate justice, and build a safer, more sustainable world. Let us not waste another moment.”
The New Collective Quantified Goal for climate finance, agreed at COP29, calls for developed nations to provide at least $300bn for climate action in developing countries per year by 2035.
However, the UNEP warned that this will be insufficient due to inflation and because the target is for both mitigation and adaptation, with the latter set to receive a lower share.
The Baku to Belém Roadmap to raise $1.3trn by 2035 “could make a huge difference”, according to the researchers, although concessional and non-debt-creating instruments are “essential” to avoid increasing indebtedness.
While the private sector must do more, the report estimates that the realistic potential for private sector investment is $50bn per year, compared to the current $5bn, and this would require targeted policy action and blended finance solutions, with concessionary public finance used to de-risk and scale-up private investment.
“Every person on this planet is living with the impacts of climate change: wildfires, heatwaves, desertification, floods, rising costs and more,” said Inger Andersen, UNEP executive director. “As action to cut greenhouse gas emissions continues to lag, these impacts will only get worse, harming more people and causing significant economic damage.
“We need a global push to increase adaptation finance – from both public and private sources – without adding to the debt burdens of vulnerable nations. Even amid tight budgets and competing priorities, the reality is simple: if we do not invest in adaptation now, we will face escalating costs every year.”
Image credit: Shutterstock
Chris Seekings is the Deputy Editor of ISEP’s Transform magazine, which is published biomonthly for ISEP members. Chris’s role involves writing sustainability-related news, features and interviews, as well as helping to plan and manage the magazine’s other day-to-day activities.
