Cop27, the UN climate summit beginning this Sunday in Egypt, could fail before it even starts if countries do not agree to put the loss and damage experienced by the poorest countries at the heart of the talks, according to climate experts and campaigners. Delegates began to arrive at the conference centre on Saturday, and the talks will formally open on Sunday with a session deciding what should be on the agenda for the two weeks of negotiations, before world leaders gather on Monday and Tuesday. But there are concerns that the talks will not properly address one of the most pressing issues, called loss and damage. This refers to the most devastating impacts of extreme weather, which can destroy a country’s physical infrastructure and tear apart its social fabric. Prof Saleemul Huq, the director at the International Centre for Climate Change and Development, told the Guardian: “I am hopeful that there will be progress at last on finance for loss and damage at Cop27. There are currently ongoing discussions on whether to include it in the Cop agenda or not. Failure to include it will mean the Cop failing before it even starts officially.” Under the UN rules, an agenda item must be agreed on at the opening session. There is widespread willingness among developed and developing countries for an agenda item on loss and damage, but the Guardian understands that some large developing economies are shying away from the issue. Harjeet Singh, the head of global political strategy at Climate Action Network International, called for developed countries at the talks to take a lead. “Rich governments must engage in a constructive manner to address the ongoing injustice of climate-induced loss and damage, by committing to deliver support to those being impacted and by phasing out fossil fuels,” he said. “This is the Cop where polluters must be put in the dock and be held accountable.” Cop27, the latest edition of the annual UN climate talks, is taking place amid high geopolitical tensions over the Ukraine war, soaring energy and food prices and a cost of living crisis around the world. Even the Egyptian hosts have admitted this will be the most difficult set of talks in at least a decade. António Guterres, the UN secretary general, said in an interview on the eve of the talks that there was a gulf between the rich – who have caused the climate crisis and failed to cut greenhouse gas emissions – and the poor, who are suffering from the effects and lack the financial resources to protect themselves. He called for this gap to be bridged by countries agreeing new ways of financing help for the poor experiencing loss and damage from extreme weather, and by big emitters reducing their carbon output faster. “There is no way we can avoid a catastrophic situation, if the two [the developed and developing world] are not able to establish a historic pact,” he said. “Because at the present level, we will be doomed.” About 120 world leaders, including the UK’s Rishi Sunak, France’s Emmanuel Macron and the European Commission president, Ursula von der Leyen, will gather on Monday and Tuesday at the conference centre in Sharm el-Sheikh, where the already stringent Egyptian security for the talks will be tightened further. Campaigning groups face having their pavilions and stalls shut down while world leaders meet, and demonstrations at the Cop will be strictly policed, while many activists will be confined to a different site. Plainclothes Egyptian government security guards were heavily in evidence throughout the conference centre and the surrounding area on Saturday. Joe Biden will come later in the week, owing to the looming US midterm elections. Boris Johnson, the former UK prime minister, is also expected. Absent will be Xi Jinping of China, Vladimir Putin of Russia and India’s Narendra Modi. King Charles III, a notable voice on environmental issues for years and a key presence at some previous Cops, has been prevented from coming, by the UK government. The talks will focus on greenhouse gas emissions cuts by developed and large emerging economies, and on climate finance for the poorest, as well as the vexed issue of loss and damage. John Kerry, the US special presidential envoy on climate, told the BBC on Saturday that loss and damage should be on the agenda. “Obviously those countries with greater means across the board – and that includes some developing countries that have greater means – need to also step up and help in this transition,” he told Radio 4’s Today programme. “We don’t view it – and we’re not going to view it – as compensation. We are going to view it as our efforts to try to help countries to adapt, to be able to become more resilient and obviously address the challenges that they face as a result of the losses and damages. You have to work out the methodology by which you are going to assign a process that works for everybody.”