Labour’s victory in the general election must mark the start of the UK’s transformation to a green and low-carbon economy and society, campaigners and experts have said as the scale of the election win became clear. The Conservatives’ U-turns on the environment had been “as popular with voters as a root canal”, according to Greenpeace, as the party sank to its worst electoral defeat in modern times. The Green party also had its strongest ever general election performance, quadrupling its representation in parliament. This, coupled with Labour’s wide margin of victory, gives Keir Starmer, the next prime minister, a strong mandate to take bold action on net zero and nature, experts and campaigners said. Ed Matthew, campaigns director at the E3G thinktank, said: “Dependence on oil and gas has driven the cost of living crisis. By delaying and damaging the clean energy policies that could cut energy bills, Rishi Sunak pitched the Conservatives against every UK household. It was a catastrophic political blunder.” Starmer must fulfil his manifesto pledge, which called for the UK to become a “clean energy superpower”, said Matthew. “The landslide means Starmer now has a historic public mandate to accelerate climate action, invest in the industries of the future, and restore UK climate leadership,” he added. “The UK is back in the race to net zero.” Mike Childs, the head of policy at Friends of the Earth, said the recent extreme weather showed how urgently the new Labour government must take action. “Given how rapidly the state of our planet is deteriorating globally, with a deadly hurricane tearing through the Caribbean as we speak, wildfires raging once more across California, farmers in the UK struggling to grow crops following an unseasonably wet winter, and nature in deep decline, it couldn’t be more imperative that the new government makes the environment a top priority,” he said. Labour could take the lead, not just in reforming the UK’s energy system and industrial base, but also on the world stage, said Edward Davey, the UK head of the World Resources Institute. “There is a wonderful opportunity – as well as a pressing responsibility – for the new government to show its citizens, as well as the world at large, what it means to be a leader on climate, development and nature once again,” he said. The list of tasks for Labour will include reforming planning to allow onshore windfarms in England, to boost solar farms, and to allow grid connections. More public transport, boosting the take-up of heat pumps, and home insulation will all be key. There must also be a “just transition” to help workers in fossil fuel dependent industries to move to jobs in cleaner sectors. The UK’s natural environment is also in a dire state, with sewage in rivers and on beaches, air pollution costing as many as 36,000 lives a year, and wildlife abundance plummeting. This will require, and soon, a detailed strategy on how the UK can achieve its legally binding target of net zero greenhouse gas emissions by 2050, said Bob Ward, policy director at the Grantham Institute on Climate Change at the London School of Economics. “The outgoing Conservative government lost its credibility on climate change by insisting it was still committed to our statutory target while weakening the policies to meet it. [Labour] needs a clear roadmap within the next few months for how to decarbonise the power sector by 2030, a hugely ambitious target that will need a national effort,” he said. Areeba Hamid, co-executive director at Greenpeace, called for Starmer to “seize the opportunities for economic revival and energy independence” offered by renewable energy and green jobs. Despite Labour’s landslide, she warned Starmer against complacency. “Labour’s victory could have been even more emphatic, had it not been for votes cast to the Greens and Lib Dems, who stood on much bolder climate and nature pledges and fair tax reforms,” she said. “Starmer must take note.” Before the election, there were indications that some influential people in the top echelons of the Labour election machine had doubts over the party’s net zero promises. Pat McFadden and Morgan McSweeney, Starmer’s chief campaign managers, were said to be instrumental in watering down the longstanding pledge to invest £28bn a year in the green economy, which was roughly halved in February over fears that the Tories would make it a target of their attacks. The result of the election proved conclusively that “flipflopping” on green issues was a turn-off for the public, according to Craig Bennett, the chief executive of the Wildlife Trusts. “All the attempts to make culture wars out of the climate and nature crises in the last eighteen months did not help the Conservatives one little bit, and that’s a very important lesson for all parties,” he told the Guardian. “All the opinion polls showed that the environment was very high on the public agenda, and that has not been tapped into by our political leaders. … Labour needs to learn this,” he said. Reform UK also had a strong showing in many areas, winning relatively few seats but coming second in many constituencies. The party has an explicitly anti-net zero stance, and many of its candidates have denied the science of the climate crisis. Matthew, of E3G, said other parties should not conclude from this that there is a strong anti-net zero tendency among the UK public, however. “Polling shows that people who vote Reform are mostly voting on immigration – that’s what really motivates them,” he said. But he worried that the new grouping of Reform MPs could exert pressure on the Tory party, driving the “culture war” over the climate crisis.