This is the first time developing countries have received such assurances, and the first time the phrase "loss and damage from climate change" has been enshrined in an international legal document.
Developing countries had been fighting hard for the concession at the fortnight-long UN climate change talks among 195 nations in Qatar, which finished after a marathon 36-hour final session.
Ronald Jumeau, negotiating for the Seychelles, scolded the US negotiator: "If we had had more ambition [on emissions cuts from rich countries], we would not have to ask for so much [money] for adaptation. If there had been more money for adaptation [to climate change], we would not be looking for money for loss and damage. What's next? Loss of our islands?"
Ruth Davis, political adviser at Greenpeace, said: "This is a highly significant move – it will be the first time the size of the bill for failing to take on climate change will be part of the UN discussions. Countries need to understand the risks they are taking in not addressing climate change urgently."
Ed Davey, the UK energy and climate secretary, said: "It's about helping the most vulnerable countries, and looking at how they can be more resilient."
But the pledges stopped well short of any admission of legal liability or the need to pay compensation on the part of the rich world.
The US had strongly opposed the initial "loss and damage" proposals, which would have set up a new international institution to collect and disperse funds to vulnerable countries. US negotiators also made certain that neither the word "compensation", nor any other term connoting legal liability, was used, to avoid opening the floodgates to litigation – instead, the money will be judged as aid.
Key questions remain unanswered, including whether funds devoted to "loss and damage" will come from existing humanitarian aid and disaster relief budgets. The US is one of the world's biggest donor of humanitarian aid and disaster relief, from both public and private sources. It will be difficult to disentangle damage inflicted by climate change from other natural disasters.
Another question is how the funds will be disbursed. Developing countries wanted a new institution, like a bank, but the US is set against that, preferring to use existing international institutions. These issues will have to be sorted out at next year's climate conference, in Warsaw, where they will be bitterly contested.
Davis said: "This [text] is just the beginning of the process – you need to have a finalised mechanism. But it will concentrate minds on the fact that it is in the best interest of countries all over the world to start cutting their emissions quickly." Governments also rescued the Kyoto protocol, the initial targets of which run out at the end of this year. The EU, Australia, Norway and a handful of other developed countries have agreed to take on new carbon-cutting targets under the treaty, running to 2020.
A separate strand of the negotiations, set up to accommodate the US because of its refusal to ratify Kyoto, was closed. This will allow unified discussions to begin on a global climate treaty that would require both developed and developing countries to cut their emissions. The treaty is supposed to be signed in 2015, at a conference in Paris, and come into effect in 2020.
The next three years of negotiations on the treaty will be the hardest in the 20-year history of climate change talks because the world has changed enormously since 1992, when the UN convention on climate change was signed, and 1997, when the Kyoto protocol enshrined a stark division between developed countries – which were required to cut emissions – and developing countries, which were not.
China was classed then as a developing country, and although it still has about 60 million people living in dire poverty, it is now the world's biggest emitter and will soon overtake the US as the biggest economy. It has made clear its determination to hang on to its developing country status, and that the countries classed as developed in 1997 must continue to bear most of the burden for emissions cuts, and for providing funds to poor countries to help them cut emissions and cope with climate change.