The target is seen as crucial to winning the trust of developing countries to make their own CO2 cutting commitments in Glasgow next week, but stood $20bn short in 2019.
Now the study confirms the original target of $100bn by 2020 has been missed, but expresses “confidence that it would be met in 2023”.
A disappointed Oxfam said: “This plan claims that rich nations will meet their target three years late.”
Germany and Canada were handed responsibility for piling pressure onto the richest nations to make commitments to stump up the missing billions, in the run up to Cop26.
The report says its projection that $100bn will be achieved in 2023 is “based on pledges made by developed countries as of 20 October, 2021”.
The UK has pledged around £2.3bn each year until 2025, but The Independent revealed the cash will be swiped from the shrunken foreign aid budget – despite a requirement that they be “additional”.
The delay until 2023 was attacked by aid groups including ActionAid International, which called the announcement “the bare minimum needed to build trust in the climate talks”.
“Making good on a promise made more than a decade ago is setting a pretty low bar for a successful Cop26,” said Teresa Anderson, the organisation’s climate policy coordinator.
She also warned that 71 per cent of support is in the form of loans, which is “pushing climate vulnerable communities deeper into debt and poverty”.
Jan Kowalzig, senior climate policy adviser at Oxfam, pointed to “the money that poorer countries are owed for every year they fell short”.
“This shortfall, which started to accumulate in 2020, will likely amount to several tens of billions of dollars,” he said.
“These are achievable amounts of money – governments have spent trillions on Covid-19 fiscal recovery packages, which show their ability to act in an emergency. This is an emergency.”
The UK has declined to increase its pledge – made two years ago – as a respected thinktank suggested it is shortchanging developing countries by around £1.9bn a year.
Germany and France are among leading contributors, while Australia, Canada and the US are low payers – while Italy, Spain, Portugal and Greece have been criticised for confusion over their donations.
The UK government admitted it was “disappointing that the goal has not been met so far”, but Cop26 president Alok Sharma said “progress” was now clear.
The announcement was “a step towards rebuilding trust and gives developing countries more assurance of predictable support,” he argued.
But Matthew Pennycock, Labour’s climate change spokesman, called the wait until 2023 “of the utmost concern”.
“This is a matter of trust for states on the frontline of the climate crisis and every wealthy country falling short, including the UK, will need to do more to reassure them,” he said.
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