Plaid Cymru's Treasury spokesperson Ben Lake MP writes for the Sunday Times

As the eyes of the world turn to Glasgow for the most important UN climate conference to date, the Chancellor has a golden opportunity to show leadership. When he steps up to the Despatch Box to deliver his Autumn Budget on Wednesday, the climate crisis should be at the forefront of his mind.

The IPCC’s most recent report stated that “unless there are immediate, rapid and large-scale reductions in greenhouse gas emissions, limiting warming to…1.5 °C…will be beyond reach.”

Today, we live in a world with global warming of 1.1°C, yet it is a world already ravaged by forest fires and increasingly frequent extreme weather events. It is a world made poorer by rapid biodiversity loss and made more geopolitically unstable by profoundly changing climate patterns. Despite that, it is not unreasonable to suggest that we are living through the last days of relative climatic, environmental, and ecological stability. It is this realisation that makes COP26 and its outcome so important.

So far, the UK Government’s net zero strategy has been undermined by the Treasury’s refusal to allocate adequate funding to realise the welcome statements emanating from a number of Whitehall departments. The Government’s net zero strategy published earlier this week contained laudable ambitions on renewable electricity generation, decarbonising household heating, and on reducing the carbon footprint of our transport sector. However, without the Treasury’s financial backing, these aspirations are doomed to fail.

This possibility stalks the Government’s plans to decarbonise household heating, where an otherwise worthwhile proposal is hamstrung by a lacklustre financial commitment to the extent that it is unlikely to fulfil its potential.

 The grant scheme announced for household heat pumps, for example, will benefit only about 0.3% of Welsh households, and is not accompanied by an equally important scheme to improve the energy and heat efficiency of our housing stock.

The Welsh Future Generations’ Commissioner, together with the New Economics Foundation (NEF), concluded that a national housing decarbonisation programme concluding by 2030 would require £14.75 billion of investment, with £3.6 billion coming from the UK Government, £1.7 billion from the Welsh Government and the remaining 64% through private finance, energy companies or self-funding by property owners.

Plaid Cymru will this week be urging the Chancellor to recognise the climate crisis for what it is: an existential crisis. We will be pressing for the Government’s rhetoric to be matched with action, by committing to the £3.6 billion needed to decarbonise our housing stock, which will ultimately save households all over Wales thousands of pounds on their energy bills.

Greater capital resourcing should also be given to the Welsh Government, who are responsible for housing as a devolved competence, so that they can implement a whole-house approach, addressing both insulation and heating supply.

We will also be calling for more transport funding to be allocated to the Welsh Government, which could easily be achieved by amending Treasury rules so that the ‘comparability factor’ for HS2 reflects the fact that it is an England-only project. Doing so would release funding to invest in Wales’s public transport infrastructure.

Some have argued that the cost of the green transition is unaffordable. The sums needed are indeed eye-watering, but failing to decarbonise would mean that our children, and grandchildren, will be left paying a far higher cost. It is the cost of inaction that is unaffordable. The alternative—a world aflame, flooded and barren—outweighs any short-term Treasury reservations about the cost of the green transition.

As the Chancellor finalises his Budget ahead of Wednesday, he should be asked:  do you really want to be remembered as the Chancellor who sank COP26? He faces an unenviable challenge in ensuring that the budget meets the biggest challenge of our age. Nevertheless, if the budget fails to provide the financial tools necessary to decarbonise our economy, the Prime Minister will arrive in Glasgow with little hope of persuading other nations to take decisive action to tackle the climate crisis.