Ruinous, eye-watering, crippling, stratospheric, massive. That’s the cost to the UK of beating the climate crisis, according to those who portray getting to net zero emissions as economic suicide that is being thrust on an unwilling population by posh eco-fundamentalists and zealots.

This is not just wrong, it is the exact opposite of reality. The delusions come from those with histories of climate change scepticism and could be dismissed as the latest mutant variant thrown up by the death throes of denial. But they are having a real-world impact, slowing action at the precise moment acceleration is needed.

So how did we get here? In 2019, the then chancellor, Phillip Hammond, wrote a letter to the prime minister claiming the cost of the UK getting to net zero would exceed GBP1tn. Then, in July of this year, the Office for Budget Responsibility (OBR) estimated the investment needed for net zero by 2050 was GBP1.4tn. These figures are the source of the hot air.

But this is only one side of the balance sheet. The other, conveniently ignored by the critics, carries huge cost savings due to more efficient vehicles and buildings, and the economic boost of many thousands of good jobs in the green industries that will be the growth story of the 21st century. And that’s just the start.

Getting to net zero avoids the terrible costs and suffering that unrestrained global heating is beginning to wreak on the world, as starkly laid out in the week’s IPCC report. Cutting fossil fuel burning also brings benefits such as slashed air pollution, which still kills about 40,000 people a year in the UK.

Let’s put some of that into numbers. Once the fuel efficiency savings are included, the OBR’s cost estimate falls by about 75%, to 0.4% of GDP a year. The OBR also said delaying decisive climate action by a decade could double the cost to the government.

Chris Stark, head of the government’s advisers, the Climate Change Committee, estimates that the cost of getting to net zero by 2050 would mean a mere four-month delay in economic growth over 30 years, even without considering the wider benefits to society. Given the alternative – climate chaos – Stark says: “I would argue we can’t afford not to do net zero.”

Swiss Re, the insurance giant whose business is risk, agrees. It calculates a 10% loss of global GDP by 2050 without further climate action now, similar to other recent analyses. Another study suggests that breaking the 1.5C temperature limit outlined in the Paris agreement will cost far more than acting to hold temperatures down, even if rich nations have to pay for action in poorer nations. Basically, climate action is a bargain.

In the face of this, why do some still make hysterical claims of ruinous costs? The first reason is blinkered nationalism – the UK’s emissions are just 1% of the globe’s, they say. The problem here is that the UK is holding the vital Cop26 climate summit in November – why should anyone act to save the world if the host is not? Failing to act would also cede competitive advantage in green industries to other nations: kiss goodbye to “Global Britain”.

The second reason for the hysterical claims is rooted in inane free-market ideology. It is true that there are upfront costs for green technology. Electric cars cost more to buy for now, but are already cheaper to own overall.

The solution here, proposed as much by centre-right voices as the left, is ensuring the less well-off get the help they need, such as subsidised electric vehicles or payments funded by carbon taxes levied on the high consumption of the wealthy. To those further to the right, such state redistribution is anathema, which may be why none of those complaining of the costs of net zero seem able to come up with any alternative plans.

They claim to be concerned about struggling families, but as Sam Hall, director of the Conservative Environment Network, says: “If we were to pursue the alternative approach of not mitigating climate change, unfairnesses in society would be exacerbated. Low-income households, for example, are disproportionately exposed to flood risk.”

The cries of “crippling net zero costs” may be laughable, but they are causing damage, and not just because they are helping delay cuts to carbon emissions. The chancellor, Rishi Sunak, is dragging his feet over urgently needed green policies, such as the plan to phase out gas boilers, at just the moment when the UK needs to be leading the way ahead of Cop26.

A reckoning is coming. The Treasury must publish its review of the costs of the net zero transition in the coming months, which is said to be being redrafted after a first attempt that was considered overly pessimistic in its high projected costs. If the final report accepts the compelling logic that climate action is both vital and affordable, the UK may yet lead Cop26 to the successful outcome the world desperately needs. If not, the cynics – those who know “the price of everything and the value of nothing” – will have won, and the world will continue to burn.

• Damian Carrington is the Guardian’s environment editor