Green campaigners and climate experts are set for disappointment as the UK government prepares to publish its carbon target for 2030. Environmental and development groups have been pushing the prime minister to opt for a stretching target of cutting emissions by 75% by 2030, compared with 1990 levels, which would have put the UK at the forefront of developed countries in fighting the climate crisis. The UK is to host vital UN climate talks – called Cop26 – in Glasgow next November, postponed by a year by the pandemic, at which all nations will be expected to come forward with national plans on emissions. Known as nationally determined contributions (NDCs), these plans for carbon curbs by 2030 are the bedrock of the 2015 Paris climate agreement. As host, the UK will be expected to show leadership on its NDC, in the hope of pushing other countries towards the tougher targets needed. Under current NDCs, submitted in 2015, greenhouse gas emissions globally would reach levels giving rise to 3C of heating, far in excess of the Paris upper limit of 2C, and likely to cause devastating extreme weather. Lord Stern of Brentford, who is an adviser to the government on Cop26, told the Guardian last month that the government should submit a 70% emissions-cutting target for its NDC. “[The prime minister] now understands that this is a growth story, not a burden,” Stern said. “But it does need strong investment and innovation.” However, the government’s target is likely to fall slightly below that figure, at 68% to 69%, though it will still represent a hastening of effort. Current plans under the UK’s carbon budgets would imply a cut of about 61% by 2030. The increased effort is not likely to cost the UK more – the committee on climate change, the government’s statutory adviser, will report next week that the costs of reducing emissions have plunged in recent years. Green campaigners argue that the rapidly falling costs mean the government should go further and faster. Research by WWF and Imperial College found that a cut of 72% by 2030 was economically feasible. A group of climate and development charities wrote to the prime minister last month calling for a 75% cut in emissions, to show leadership at Cop26. “Given the need for the UK to take on our fair share of global emissions reductions based on historic responsibility, we must move further and faster and commit to pursuing every opportunity to even exceed this target, as well as lead global efforts to close the gap to 1.5C [the lower limit on global heating in the Paris agreement],” wrote the signatories. The government is likely to hail its new target as an improvement on current plans, and a marked strengthening of the target that would have been expected if the UK was still part of the EU. Under the EU’s plans, the UK’s carbon-cutting figure could have been as low as about 65%. The EU will continue to debate its NDC next week, ahead of a Climate Ambition Summit of world leaders to be hosted on 12 December by France and the UN to mark the fifth anniversary of the Paris agreement. All NDCs are supposed to be submitted by 31 December, according to the Paris agreement, but some countries are likely to miss the deadline. President-elect Joe Biden in the US has made clear his commitment to rejoining the Paris agreement when he takes office next January, and drawing up a new NDC will be one of his early tasks. In a positive sign for Cop26, Biden also supports setting the US on a path to net-zero emissions by 2050. China, the world’s biggest emitter, set a new target of net-zero emissions by 2060, and with the EU, the UK, Japan and many other developed countries now also aiming for net zero by 2050 the stage is set for global unity on a mid-century goal of a net-zero economy. Climate Action Tracker calculated this week that these long-term commitments, if fulfilled, would lead to a rise in global temperatures of 2.1C above pre-industrial levels, not far above the upper limit set in the Paris agreement. However, the UN secretary-general, António Guterrres, warned this week that while long-term targets were a major step forward, they needed to be backed up by shorter-term policies and actions. The NDCs are seen as a vital stepping stone towards fulfilling the long-term targets on emissions, because carbon-cutting needs to start now to prevent the further build-up of carbon in the atmosphere. Guterres delivered his starkest warning yet on the climate, saying humanity was at war with its own planet. “Humanity is waging war on nature. This is suicidal. Nature always strikes back – and it is already doing so with growing force and fury. Biodiversity is collapsing. One million species are at risk of extinction. Ecosystems are disappearing before our eye,” he said. “Human activities are at the root of our descent toward chaos. But that means human action can help to solve it.”