Scientists attending Cop26 have sent a clear warning to policymakers: get a move on, because every moment of delay, every extra fraction of a degree of global heating will have dire consequences. That message has been reinforced at Glasgow with reports, forums and discussions, but those involved in channelling the science to the world’s leaders are frustrated that words are still not being matched by actions. Peter Stott, a climate scientist at the Met Office’s Hadley Centre who has been attending Cops since 1998, said he was marginally more optimistic than he had been before the Glasgow summit. “I have mixed emotions. I feel relieved that things have started to move, but I am concerned about the speed,” he said. “The scientific message we have talked about for 25 years is being acted on. That is a vindication. We might be starting to turn the corner. But I feel a strong sense of anxiety I haven’t felt before. I want to see the policymakers get a move on. In the next two years we have got to cut emissions rapidly.” He said the success or failure of this Cop would not be determined by speeches and targets but by geophysics. “We will know Glasgow had an effect by measuring the carbon dioxide concentrations in the atmosphere. That is what scientists are looking for. And now it is acknowledged internationally that these concentrations need to go down. In that sense, science has done its primary job.” New studies continue to underline the risks. This week the Hadley Centre released a report showing that 1 billion people would be at risk of extreme heat exposure if global warming reached 2C. Katharine Hayhoe, the chief scientist for The Nature Conservancy, feels humanity is getting closer to a collective epiphany – an “oh shit” moment – when people finally realise climate impacts pose a far greater threat than the solutions, and decarbonisation can be ramped up to the necessary scale of a Manhattan Project or a moon race. “I don’t think we have arrived there yet but it’s building,” she said. “I think leaders are listening to what is already happening in this world. Fifteen years ago you had to be up in the Arctic or in a low-lying island to experience climate change. Today, wherever we live we are seeing the impacts and governments are responding.” The costs are also becoming more apparent. In the 1980s, US insurers had to pay out fora $1bn disaster every three months. Now, Hayhoe says, it is every two and a half weeks. Samantha Burgess, the deputy director of the Copernicus Climate Service, said EU satellites were increasingly monitoring record fires, temperatures, and extreme rainfall events leading to floods. “We have overwhelming evidence that the costs of inaction are orders of magnitude greater than the cost of action.” Compared with the start of the conference, Burgess said she was a little more hopeful about reaching the 1.5C target because the direction of travel was clearer. “I think the motivation of everyone I have interacted with is very high in the transition to a net zero future.” But she was cautious about putting too much faith in long-distance goals. “There is a big difference between the policies drafted and the policies implemented,” she said. “Currently we are not on course for 1.5C. We need to see more political ambition on the pledges to align with the urgent changes described by the scientific evidence.” How much of a difference Cop will make is fiercely debated. Last week the International Energy Agency said the promises made in Glasgow could put the world on track to limit warming to 1.8C by the end of the century, if every country lived up to its long-term net zero commitments. This optimism was hosed down by a subsequent assessment by Climate Action Tracker, the world’s most respected climate analysis coalition, which showed how weak short-term goals were likely to push global heating to at least 2.4C. In negotiations, the most vulnerable states are now battling with big emitters to try to hold on to the 1.5C target, which is the most ambitious goal of the Paris agreement. Glasgow will almost certainly fall short, so one of the biggest challenges remaining at Cop26 is to keep that possibility alive with as much progress as possible and a more aggressive ratchet mechanism in the future. Stott feels 1.5C is difficult but worth fighting for. “It’s probably going to be almost impossible to stay below it completely. We may find a way where we briefly go above 1.5C and then come down again. But what is at stake is so enormous that even if we get close that would still be a massive prize.” Ed Hawkins, of the National Centre for Atmospheric Science at the University of Reading, concurred on the need to fight for every fraction of a degree. “Every tonne of CO2 matters. Every bit of warming matters,” he said. “There is an understandable focus on 1.5C or 2C, but there is no cliff edge. It’s a slope we are sliding down. The quicker we get off, the less bad the consequences will be.” Hawkins is the scientist behind the “climate warming stripes” that can be seen on walls, pavements, scarfs, ties and dresses in Glasgow. He is encouraged by last week’s announcements on reducing methane, coal and deforestation, but he wants policymakers to act more quickly. “Every tree chopped down and burned ends up in the atmosphere. Setting the target to end deforestation by 2030 leaves the door open for another decade of deforestation. It would be helpful if action could be brought forward.” He said warming would only stop when the world reaches net zero carbon, but emissions were heading in the wrong direction. Since the first IPCC gathering in 1988, the concentration of CO2 in the atmosphere has increased from 352 to 410 parts per million, and continues to rise. “Over the past 30 years, the physical science that explains the dangers of our interference with the climate system has become ever clearer. Yet our ability to tackle the problem seems to have stood still,” he said. “Climate needs to be part of everyday conversations. That will inspire small actions and motivate politicians to act when they see these actions are popular.”