The former vice-president has yet to put forward a plan to address global warming, which polls suggest is the single most important issue for DemocratsJoe Biden is believed to be developing a ‘middle ground’ approach but his fellow candidate Jay Inslee warned: ‘Half-measures mean full extinction of millions of species.’ Photograph: Joseph Prezioso/AFP/Getty ImagesClimate change is transforming life by redrawing coastlines, turning vast areas of forest into infernos, stirring enormous storms and spreading exotic diseases. An indirect casualty of this upheaval could be Joe Biden’s hopes of becoming US president.Biden, frontrunner in the polls to secure the Democratic nomination, has not laid out a plan to address the crisis.This is set to change, according to Reuters, with the Biden campaign working on a strategy to reinstate climate policies torn down by Donald Trump, such as restrictions on coal-fired power plants and vehicle fuel efficiency requirements.Sign up for the US morning briefingThe plan, which is being worked on by the former Barack Obama adviser Heather Zichal, would see the US remain in the Paris climate agreement and offer support for nuclear energy and also natural gas, which is generally cleaner than coal but still emits planet-warming pollutants. Biden is also said to favour nascent carbon capture technology, which aims to contain and store emissions from industrial facilities.But this “middle ground” approach has been roundly attacked by environmental groups and progressive Democrats for being woefully insufficient.More importantly, it does not appear to chime with the urgent action scientists say is required to avert disastrous climate change. A landmark UN report last year stated that “unprecedented”, “rapid and far-reaching” transformations across energy, land use and transportation are needed to avoid increasingly dire flooding, wildfires, heatwaves, food insecurity and unrest.“A ‘middle ground’ policy that’s supportive of more fossil fuel development is a death sentence for our generation and the millions of people on the frontlines of the climate crisis,” said Varshini Prakash, director of the Sunrise Movement, a youth climate change organization allied to progressive Democrats such as the New York congresswoman Alexandria Ocasio-Cortez.“Biden’s betting that a retreat to mediocrity and tepid policymaking will garner him the Democratic nomination, but climate change is a top issue in this election and voters expect candidates to put forward solutions in line with the crisis.”Ocasio-Cortez has championed the Green New Deal, which calls for a national mobilization against climate change on a par with the second world war. The concept has garnered support among some of Biden’s rival presidential nominees including senators Bernie Sanders and Elizabeth Warren.The GND, perhaps alongside the severe hurricanes and wildfires that have rattled Americans over the past two years, has helped elevate the issue of climate change to a leading priority for Democratic voters.A CNN poll in April found that climate change was the single most important matter for Democrats, eclipsing healthcare, gun control and impeaching Trump, with 96% saying it was somewhat or very important to them.This rapid shift in priorities threatens to cast Biden’s candidacy as out of touch, even at this early stage. A climate plan deemed feeble by primary voters could harm the former vice-president in a new landscape where the Democratic National Committee is being pushed to hold a climate change-only debate and one candidate, the Washington governor, Jay Inslee, is running solely on the issue of global warming.The Green New Deal, supported by Alexandria Ocasio-Cortez, is setting the agenda on climate change for the Democrats. Photograph: Saul Loeb/AFP/Getty Images“We cannot simply go back to the past; we need a bold climate plan for our future,” Inslee said of Biden’s stance on climate change.“Facing a crisis does not permit half-measures. Half-measures mean full extinction of millions of species and full economic damage to communities across America.”Biden has never been at the forefront of the climate movement but is positioning himself as a pragmatic operator who gets things done, including having aided the passage of the Paris climate deal.In a recent rally in Iowa, Biden said he was “one of the first guys to introduce a climate change bill, way, way back in 87”, a reference to his successful attempt to get President Ronald Reagan to set up a taskforce on the issue.TJ Ducklo, a spokesman for Biden, tweeted that the former vice-president had called climate change an “existential threat”.“He knows how high the stakes are,” Ducklo tweeted. “As president, Biden would enact a bold policy to tackle climate change in a meaningful and lasting way, and will be discussing the specifics of that plan in the near future. Any assertions otherwise are not accurate.”Proponents of the GND hope that if Biden does manage to secure the Democratic nomination he will embrace the plan due to its focus on creating high-paying jobs in clean energy generation. The worry for climate activists is that the issue could revert to being largely overlooked, much like in the 2016 election, should Biden end up facing Trump in the 2020 contest.“If you’re running to lead the nation, you need to have a plan on climate change given it will be the most catastrophic thing to happen to us,” said Rhiana Gunn-Wright, policy director at New Consensus, which helped design the Green New Deal. “It’s disappointing Joe Biden hasn’t said more. Beto [O’Rourke], Warren and Inslee have all released a plan, so Biden in many ways is an outlier.“The next presidential election will be crucial, but this is a movement not solely focused on that. The Green New Deal is built to exist beyond this election season. People are energized and they want to fix this,” Gunn-Wright said.