Sarah Newton is MP for Truro and Falmouth, and is a former Minister of State at the Department of Work and Pensions.

Through the pioneering Climate Change Act, through its G7-leading emission reductions and its successful innovation in clean technology, Britain can rightly claim to have been a leader in climate change ever since Margaret Thatcher called for a United Nations treaty 30 years ago. The scientific evidence base has developed significantly since then with commensurate commitment to take action. It’s essential that policy makers are guided by evidence – and it is now clear that the U.K. needs to move towards net zero emissions by 2050. As Isabella Lövin, Sweden’s Deputy Prime Minister, said last year, a nation cannot claim since the Paris Agreement to be a climate change leader if it does not have a net zero target.

If the arguments against taking action now seem familiar, that may be because we have been here before. A decade ago, to be precise, when the UK Parliament approved the world-leading Climate Change Act, some claimed that the move would will damage the economy, that other country would reduce its emissions, and that energy bills would go through the roof.

None of this happened. What occurred instead was a British success story. We grew our economy, and cut our carbon emissions by more than any other G7 nation. Employment is at record levels. Energy bills have gone down for a decade. Internationally, British leadership helped forge the Paris Agreement – the first time all nations agreed to curb their greenhouse gas emissions – and nation after nation is passing climate change legislation modelled on the UK Act. In fact, decarbonisation has proved so much cheaper than anticipated that cutting our emissions to zero is now forecast to cost the same as the 80 per cent cut was forecast to cost a decade ago.

The Treasury’s old orthodoxies need reconsidering. The Governor of the Bank of England has warned of the risks of climate change to our financial system. Now is not the time to delay, but proceed with carefully considered cross-government planning to reach net zero by 2050. All delay will do is to postpone Ministers making a decision that it will inevitably make anyway – inevitably because the scientific and political cases are unarguable. And by delaying, it will make implementation harder and more expensive. Business likes clarity; which is exactly why the CBI is urging government to make a decision now.

Yes, there will be challenges. But they are being met. To take one example; the Treasury officials warn that net zero means significant changes for farmers. Howeve,r the NFU has already set itself the ambition of getting to net zero agriculture – and by 2040, not 2050. Steel, aluminium, shipping – in all of the “difficult’ areas we find companies such as Maersk, Rio Tinto, Vattenfall and our own Liberty Steel stepping up with commitment and innovation.

Meanwhile, the Government recently took delivery of a comprehensive and detailed report from its statutory and expert advisors, the Committee on Climate Change. It concludes that the evidence for moving to a net zero economy by 2050 is overwhelming. It lays out how that can be done, shows the cost is eminently affordable, and demonstrates that the transition is more feasible and more affordable if we start now.

Politically, the risks of vacillating are huge. Net zero is already Labour Party policy. If the Prime Minister allows her plans to be diluted this week, the Conservatives will hand yet another electoral advantage to Jeremy Corbyn.

The appetite for action to reach net zero is huge amongst businesses and people of all ages. Leaving the environment in a better condition for the next generation is a core Conservative value. That is why alongside the CBI and NFU, scientists, a clear majority of MPs, faith leaders and doctors are among those constituencies calling for target to be urgently set.

Of course taxpayers’ money should be spent wisely. In reality, many solutions already exist and we must move forward in implementing them. Next week, I will introduce a 10 Minute Rule Motion, outlining the opportunities of a well thought through National Home Insulation Plan that would reduce emissions and save people on low incomes about £400 a year by upgrading their energy efficiency measures. As I have seen from Cornwall’s Winter Wellness programme, enabling people to live in warm homes improves their health and wellbeing, including supporting participation in education and employment. The models Treasury officials use need a more comprehensive set of measures to reflect the costs and savings of taxpayer investment.

We understand that the Treasury is concerned that a net zero target means a near-term increase in public expenditure. The UK already has to meet legally-binding carbon targets out to 2032, and those targets will not change. The Industrial Strategy’s Clean Growth programme of activity sets out the economic benefits. The Environment Bill and Agriculture Bill too. The Treasury’s economic modelling needs to look at a wider range of impacts, improved productivity, employment and exports as well as reduced NHS costs from cleaner air are some obvious ones.

Let’s be a bold Britain – we were the crucible of the first industrial revolution, let’s lead the fourth, high tech, clean growth industrial revolution. The Prime Minister is a great public servant and legislating for net zero emissions would be the best legacy she could achieve.