Adaptation finance needs are 10-18 times as great as the current international finance flows, the United Nations estimated in a report on Thursday, flagging how rich countries were faltering on their promises to developing nations to adapt to a changing climate despite record breaking temperatures and severe climate extremes.

The shortfall is now 50% bigger than previously estimated, the report, “Underfinanced. Underprepared” by the UN Environment Programme, said.

The 2009 pledge by developed countries to provide $100 billion a year in climate finance to poorer nations, and mobilising funds, is likely to be a key talking point at COP28 negotiations in Dubai at the end of November.

The $100 billion pledge, which has not been fully secured, was aimed at helping poorer countries not only mitigate climate change by cutting greenhouse gas emissions, but also to adapt to rising temperatures and sea levels.

Neither the goal of doubling 2019 international finance flows to developing countries by 2025 nor a possible New Collective Quantified Goal for 2030 will significantly close the adaptation finance gap on their own, the report concluded, identifying seven ways to increase financing, including through domestic expenditure and international and private sector finance.

However, the annual financing shortfall for adaptation alone now stands at $194 billion to $366 billion, with existing financial flows reaching just $25 billion during the 2017-2021 period, the UNEP report said.

“Failure to reinvigorate investments in adaptation action will inevitably lead to more unabated climate impacts and subsequent loss and damage. This will make debt-ridden developing countries even more vulnerable to climate-related extreme events and slow-onset changes,” the report said.

The adaptation costs are projected to rise significantly by 2050 with the risks from climate crisis growing.

Global average temperatures are already exceeding 1.1°C above pre-industrial levels, and the current plans reflected in the Nationally Determined Contribution (NDCs) are putting us on a path towards 2.4°C-2.8°C by the end of the century.

The report also assessed the adaptation finance needed to implement domestic adaptation priorities, estimated to be $387 billion per year in this decade.

The estimated new range of $215 billion to $387 billion a year is equivalent to 0.6%-1% of all gross domestic product (GDP) of developing countries combined.

The international public climate finance flows to developing countries decreased by 15% to $21.3 billion in 2021 after having increased to $25.2 billion between 2018 and 2020.

International public adaptation finance over the past five years has also suffered from a low disbursement ratio, at 66%, as compared to the overall development finance disbursement ratio of 98%.

In the same period, the report highlighted, mitigation finance continuously increased.

“In 2023, climate change yet again became more disruptive and deadly: temperature records toppled, while storms, floods, heatwaves and wildfires caused devastation,” said Inger Andersen, executive director of UNEP in a statement.

“These intensifying impacts tell us that the world must urgently cut greenhouse gas emissions and increase adaptation efforts to protect vulnerable populations. Neither is happening. Even if the international community were to stop emitting all greenhouse gases today, climate disruption would take decades to dissipate,” she added.

Five out of six countries have at least one national adaptation planning instrument, the UNEP said, but the number of adaptation actions supported through international climate funds has stagnated for the past decade.

In a first, the annual report also examined loss and damage as a function of failure to adapt.

The report pointed to a study indicating that the 55 most climate-vulnerable economies alone have experienced losses and damages of more than $500 billion in the last two decades. These costs will rise steeply in the coming decades, particularly in the absence of forceful mitigation and adaptation.

Reacting to the report, UN secretary-general Antonio Guterres asked governments to tax “the windfall profits” of fossil fuel companies and direct some of the proceeds to people already suffering “loss and damage” from climate impacts.

“Fossil fuel barons and their enablers have helped create this mess; they must support those suffering as a result. I call on governments to tax the windfall profits of the fossil fuel industry, and devote some of those funds to countries suffering loss and damage from the climate crisis,” he said.

“Developed countries must present a clear roadmap to double adaptation finance as promised – prioritising grants over loans – as a first step towards devoting half of all climate finance to adaptation. Multilateral Development Banks should also allocate at least 50% of climate finance to adaptation, and change their business models to mobilise far more private finance to protect communities from climate extremes,” he said.