The US must act urgently to get its environmental policy back on track before the Cop26 climate change conference later this year, leading scientists and academics said. America also needs to do “its fair share” in financing environmental policies after “four lost years” during the Trump presidency. Environmentalists see 2021 as the key year for governments to unite behind a global policy to tackle the crisis. “This is a massively important year for climate diplomacy,” said Rachel Kyte, Dean of the Fletcher School of Law and Diplomacy in Massachusetts. “But the US is back and ready to join a race to zero carbon emissions.” On Friday, the US will officially re-enter the Paris Agreement after former president Donald Trump made it the only country to leave, withdrawing in 2017. One of President Joe Biden's first acts was to sign an executive order to rejoin the climate accord signed by 189 countries. “We now have a president that understands the science and understands the need to act with urgency and understands the grave harm of the four precious lost years,” said Rachel Cleetus, director of the US Union of Concerned Scientists. The US commitment to the Paris Agreement has been given greater urgency after a devastating year for climate-related disasters in 2020. "All over the world there were extreme heatwaves, floods, supercharged hurricanes, cyclones, typhoons and terrifying wildfires," Ms Cleetus told the Energy and Climate Intelligence Unit media briefing. "Here in the US we've seen 22 extreme weather and climate related disasters, last year, that each cost more than a billion dollars." As America was one of the leading contributors to the problem it therefore “must do its fair share” which includes an ambitious financial climate package “well ahead” of the Cop26 climate change conference, Ms Cleetus said. Ms Kyte called on the US to more than half its carbon emissions by 2030, as well as provide billions of dollars to help renewable energy and other projects. Cop26 needed an agreement with "deep cuts from those economies that are responsible for the majority of the emissions of the world", she said. She added that Britain and America's close alliance "needs to be more special than ever" to drive through changes at Cop26, which will be held in Glasgow in November. The scientists said all eyes would be watching on April 22, when the US announces its Climate Action Plan. “People around the world are in desperate need of policymakers to step up and do the right thing,” said Ms Cleetus. “That's what we need to see happen this year ahead of Cop26. We need to see the top global diplomacy, the US, China, EU, the UK, really setting a high bar for ambition delivering on the details.” The conference heard that African countries were facing unprecedented droughts, floods and heatwaves that were destroying crops. But the continent also needed the West’s renewable energy technology. “They can transfer those technologies to developing countries because they cannot continue using renewable energy or cash in their own countries,” said Hindou Oumarou Ibrahim, founder of the Association for Indigenous Women and Peoples of Chad. She added that indigenous peoples protect 80 per cent of the world's biodiversity. “I call here to President Biden to support indigenous peoples worldwide because we are those who can make a difference. We protect the forests of the Amazon. We protect the ice in the Arctic. We are the ones who are building the Great Green Wall in the Sahel region. We are the ones who are putting our traditional knowledge to protect all our oceans.” The Cop26 climate change conference will start in Glasgow on November 1 this year