When the UK became the first major economy in the world to commit to reducing its carbon emissions to net zero by 2050, there was so little disagreement among MPs it was simply ‘nodded through’ without a vote.

Six years on, the political climate is very different, the consensus at Westminster has shattered and reaching net zero is fast becoming a political dividing line.

Labour has committed itself to an extra deadline: reaching clean power by 2030.

The Greens and Liberal Democrats want to hit net zero faster, the Conservatives are slamming the brakes on their policy and, for the first time, there is now a mainstream party, Reform UK, openly questioning the need to reach net zero at all.

Even a former Labour prime minister, Sir Tony Blair, has said that existing global approaches to tackling climate change aren’t working (although it was later clarified that his institute supports the government’s targets).

So what’s happened?

In 2019, when the target to reach net zero carbon emissions by 2050 was set, public concern about climate change was very visible.

Thousands of people had joined Extinction Rebellion marches and the then-teenage activist Greta Thunberg was so influential she was invited to address MPs in Parliament.

Luke Tryl, pollster for More in Common, says he has not found a significant drop in concern about climate change or support for net zero, even if we’re not seeing people on the streets.

What has changed, he says, is the conversation around it which, after the rising cost of living and the war in Ukraine, has switched to “how does this reflect on people’s pockets and does it make people think the country is safer as a result?”

He also says the debate has become “more polarised between left and right” with Labour and Lib Dem voters seeing it as a “top three” issue, while Reform voters are more opposed to net zero but less motivated by it: only one in 10 people vote Nigel Farage’s party because of net zero, Tryl’s research suggests.

He also says that politicians are more divided than everyone else.

“The fracturing of the consensus has been far more profound at what we’d call ‘elite level’ rather than at public level,” he says.

Undoubtedly, part of the rise in the conversation about climate targets has been driven by the rise of Reform, which has made what it calls “net stupid zero” one of its major campaign issues.

Deputy leader Richard Tice says his party – which has just won a by-election and made major gains in local elections – has forced the issue onto the political agenda.

“On the doors, people are talking about immigration but the next thing they talk about is the price of everything, the bills, the cost of living. When you drill into it, the message is getting across that the increase in the cost of living is significantly due to the increase in energy costs.

“The awareness of the stupidity of this has transformed in the last six months, because of the destruction of jobs and bills. People are waking up all over the place.”

For the Green Party of England and Wales Co-Leader, Adrian Ramsay, the fracturing of consensus is “distressing” and he blames party politics.

“There are parts of the political spectrum that are determined to turn this into a political football but I think reasonable people within all parties need to resist.”

He says people do need to feel they are included in climate measures and believes there is a “sensible climate majority” within Parliament, whose job it is to make the right policies to bring people along with them.

“Of course it has to be done in a way that brings people with us and there is a risk that there’s too much onus put on individuals so when it comes to things like public transport, for instance….the greener option needs to be the cheaper option.”

There are also those that think the UK is starting to import the more partisan politics on the issue from the US.

Pippa Heylings, the Liberal Democrats’ net zero spokesperson, says she thinks part of the pushback is being driven by “big oil and gas” who, she says, have been “emboldened by Donald Trump”.

Another is that the easy things have already been done and “we’re now getting to the things that will touch on people’s lives”.

Her party’s policy is currently to reach net zero by 2045 although she says they are looking at it to make sure it is still “do-able” after the previous Conservative administration shifted the government’s timeline.

The most marked political shift has come from the Conservatives, who have moved from setting the 2050 target, enthusiastically embracing green goals set by Boris Johnson, to a slowing of some targets under Rishi Sunak and, finally, abandoning 2050 under Kemi Badenoch.

She has described the 2050 plans as “impossible” and said that what Keir Starmer needed to do was to “scrap what [Energy Secretary] Ed Miliband is planning which is actually going to bankrupt the country”.

“It’s not workable. Conservatives are working on new plans so that we can tackle climate change and look after our environment, without bankrupting the UK.”

Green-minded Tories have said they thought the decision to ditch the target was premature but they hope their party will recommit to decarbonisation.

Sam Hall, the director of the Conservative Environment Network, said: “On the centre-right there have been growing concerns around the cost of the transition and the shift to a more statist, interventionist approach to decarbonising.”

He says he wants to see a more “market-led” solution.

While much of the Labour Party does seem to be on board with the leadership’s position, there are some in the broader Labour movement who have issued warning shots that suggest their support for net zero is conditional.

Some trade unions have become increasingly vocal about the need to ensure that there is a plan to protect jobs in any transition to green energy.

As the union Unite put it: “If they fail to do this, then Labour cannot expect workers to support their net zero plan.”

While the net zero by 2050 target is currently set in law, Labour’s “clean power by 2030” push is self-imposed, leading to regular rumours that it could be watered down.

Government sources are adamant the party is committed to it, and they point to investments that have already been made.

Other Labour sources, who back the targets, say they believe the prime minister is invested in it and that it is intrinsically linked to the government’s growth agenda.

They also warn that any watering down of targets would shake confidence in foreign investment.

Former Labour advisor John McTernan believes that keeping the clean power commitment is also key to the government’s political survival beyond the next election.

“Labour has to be solid on it because it’s a manifesto commitment and because it is a point of distinction with the parties on the right.

“If you’re going to be picking up voters from the centre-left pool, you’ve got to have a proposition for them to vote for.”

He says the party won a big majority by promising “big, difficult things”.

“It would be a dereliction of duty for the Labour party to win a landslide on difficult things and then go, ‘do you know what, it’s too difficult’.”

With so much political capital and economic hope riding on Labour’s green agenda, pulling back from green targets could be fraught with danger.