A new wave of climate activism, during which motorways have been blocked and politicians confronted by young people, is attempting to put pressure on the UK government before the UN Cop26 climate conference in Glasgow later this year.

Insulate Britain staged its first protest on Monday and has since brought large sections of the UK’s busiest motorway to a standstill to demand action to tackle the escalating climate emergency.

On Friday, activists once again glued themselves to the road at key junctions around the M25 causing long tailbacks, confrontations with angry drivers and condemnation from ministers, before being arrested and removed by the police.

Meanwhile, young people from the recently formed group Green New Deal Rising have been confronting leading politicians including Rishi Sunak, Nicola Sturgeon, Keir Starmer and most recently the US Democrat Nancy Pelosi during a visit to Cambridge on Thursday.

They demanded on camera that the politicians back a Green New Deal to tackle the “intersecting crisis” of climate breakdown and rising inequality, with the films made by the group watched hundreds of thousands of times.

Earlier this summer, the Intergovernmental Panel on Climate Change warned of unprecedented and irreversible changes to the Earth’s climate, which is destined to rise by at least 1.5C. The UK government’s own climate advisers said ministers had failed to come up with the policies needed to reach their net zero targets.

In light of these stark warnings, both Insulate Britain and GND Rising are calling for urgent policy changes. Insulate Britain wants all homes in the UK insulated by 2030, not just to cut carbon emissions but also to tackle fuel poverty and create jobs.

GND Rising wants to make the climate crisis the “defining political issue” at Westminster in order to tackle the ecological crisis.

Fatima Ibrahim, 28, a co-founder of GND Rising, said that although the group launched only in the summer it had already trained up 1,000 volunteers, amid growing anxiety and anger among young adults.

“We are tapping into concerns about the climate crisis, but also inequality and the fact we are the first generation who will probably be worse off than our parents,” Ibrahim said.

She said those concerns included the “increasingly precarious jobs market and disintegrating public services. People who worry about any of those things have a home in [the] GND Rising movement.”

Volunteer activists from the group have already targeted several politicians and Ibrahim said it had a twin strategy of putting MPs on the spot and building support for the programme in communities around the country, with online training sessions and teams of volunteers researching which MPs to target and where best to intercept them.

“The role that we have to play – and what is hopeful in what we are doing – is we actually have a plan we are pointing towards, something that feels like it meets the challenges that we face and we can finally talk about what needs to be done and not what needs to be stopped.”

The group has made efforts to a recruit a more diverse range of activists. Georgina Bell, 22, said that as a black woman she had often found it difficult to fit into other environmental groups, but she said GND Rising had made “a huge effort to make space for people of colour and other, often marginalised, groups”.

“Not only does it actively recognise me, it actively encourages loads of smaller communities who have usually been marginalised to take a full part … we went away on a weekend training programme recently and I have never seen so many different people from different ethnicities, from different levels of ability and all over the LGBTQ + spectrum – I was just blown away.”

The emergence of these groups follows a fallow period for climate activism. In 2019, there was an surge in protests with Extinction Rebellion activists blockading large parts of central London for almost two weeks and hundreds of thousands of school and college students taking to the streets inspired by the Swedish climate activist Greta Thunberg.

The pandemic and subsequent lockdown knocked the wind out of the climate movement as gatherings of large groups became difficult or often illegal.

But ahead of Cop26, where world leaders will hold crucial climate talks this November, there are signs of a resurgence. Tens of thousands of people from civil society groups and protest movements from across Europe are expected in Glasgow. Earlier this month, Extinction Rebellion activists took to the streets again and a Global Climate Strike will take place next week.

Insulate Britain, one of the newest groups, has already had a big impact with dozens of people arrested and condemnation from ministers, police and angry motorists.

Their tactics have been criticised, particularly after a woman was hospitalised after a collision near the scene of one of their protests this week. The cause of the crash is unknown. The transport secretary, Grant Shapps, said on Friday: “This is dangerous and counterproductive. We all agree that climate change must be tackled, but this sort of behaviour achieves nothing, puts drivers at risk and increases pollution. I expect the police to take swift action to clear the roads.”

Zoe Cohen, a spokesperson for the group and a former NHS worker and activist with XR, issued a “deep and genuine apology” to everyone who had been affected by the hold-ups, but said the failure of the government meant the protesters had no choice.

“I can guarantee you that not a single person who has been on the roads or who is acting as a spokesperson wants to do this, it is so distressing and so stressful, but the fact is people are more concerned about the government’s inaction and recklessness than their own wellbeing.”

The group has been building support behind the scenes for months. At online talks and local meetings, training and discussion groups, recruits from bricklayers to teachers, grandparents to teenagers have been signed up and trained.

Several of its activists and organisers have been involved previouslyin XR, while many others are new to protesting.

XR’s co-founder, Roger Hallam, who left the group last year, is one of those involved in Insulate Britain and was arrested before the group’s protest on Wednesday.

But although some of its members and tactics are familiar from XR’s previous protests, its focus on one specific demand of “insulating British homes” is a deliberate attempt to make the crisis about “bread and butter” issues of housing, fuel, poverty and jobs as well as carbon emissions.

As Hallam told an organising meeting in June: “Insulating the housing in the UK is the most no-brainer move to reduce carbon emissions per unit of investment.”

On Thursday, the home secretary, Priti Patel, called on the police to take “decisive action” against what she described as the “selfish activists” taking part in the Insulate Britain protests.

But as further evidence of the climate crisis emerges on a daily basis, Cohen said the protests would continue.

“If the government was doing its job, we would not need to be here. They can sort this in five minutes by putting out a statement that says you are serious about protecting British families and their homes.”