The Tories, the media and right-wing Labour MPs appear to be of one voice on the importance of spending a vast fortune on the next generation of submarine-based WMDs.

Jeremy Corbyn’s insistence that he would never use them has apparently cast him into the wilderness of the unelectable and the dovishly naive. Russia’s Putin is apparently rubbing his hands with glee at the thought of Britain’s imminent nuclear nakedness.

But in an age of austerity, when the government claims it has to cut the income of three million low-income families to the bone, while slashing subsidies for renewable energy following the hottest year on record, surely the question of value for money in achieving security for Britain should be paramount?

It’s not as if climate change has no impact on national security. Charlotte Church was sneered at for mentioning a report that found Syria’s uprising was in part caused by a severe drought over three years that drove thousands of people off the land and into slums prior to the 2011 protests.

Across the world, traditional rain patterns are being disrupted by climate change, adding to stress in regions that are already wracked by social violence. When the Pentagon recognises climate change as a bigger threat to global security than terrorism, the smart move for policymakers would be to invest heavily in green energy, not blow the nation’s resources on an unusable instrument of nuclear terror.

The cost of the subsidy for renewables soon to be axed by the government is £1.5 billion — a billion less than Trident 2’s annual cost of £2.4bn. Britain, by investing a big part of its Trident budget in a renewable revolution, could by 2030 have created a new green economy and weaned us off dependency on Opec oil (36 per cent of oil imports) and Russian coal (42 per cent of coal imports). This change would surely offer us far greater security than to continue to rely for energy sources on countries who could, at some not too distant future point, suffer violent political change and possible economic collapse.

In a modern economy, energy security is central to national security. Following development of oil and gas production in the North Sea, Britain became a net exporter in the 1980s, but North Sea production peaked in 1999, and Britain returned to being an energy importer in 2004.

In terms of energy security things have got worse since David Cameron came to power. In 2013, 47 per cent of energy used in Britain was imported, up sharply from the 2010 level, due to the decline in oil and gas output.

In 2013 Russia remained the leading source of our coal imports, accounting for 41 per cent, with the US at 25 per cent and Colombia 23 per cent. For crude oil we rely on Norway, which accounted for 40 per cent of imports, with Opec countries — including Algeria, Nigeria and Saudi Arabia — supplying a further 36 per cent. Norway accounted for 58 per cent of Britain’s gas imports, with the remaining 20 per cent as Liquefied Natural Gas (LNG), with over 90 per cent of this coming from Qatar.

British oil production in 2013 was 70 per cent lower than the record 150.2 million tonnes in 1999. Gas production in 2013 was 66 per cent lower than the record levels seen in 2000.

So there you have it — we are increasingly import dependent for fuel, with a significant portion of this coming from Russia and Opec countries. Britain in other words, is reliant on fuel from countries — in the Gulf, Russia and Africa — who effectively have a gun pointed to our head over energy. Billionaires from these countries have been accumulating vast portfolios of British real estate, mostly in London.

In the case of Qatar and Saudi Arabia, they have funded the advance of conservative Islam across an arc from north Africa to Indonesia that has helped spur militant violence across the world.

The Tory idea of security needs to be reframed away from nuclear terror to energy security and independence. Labour’s best option to win the argument and for Britain’s future prosperity and energy self-sufficiency is to propose investing a big portion of the £100bn that was due to be spent on Trident in a green economy that will genuinely give us national security in a highly unstable world.

Alternatively we can continue with Cameron’s option of dependency on oil and gas from our friends in Russia, the Middle East and Colombia, while holding a very expensive stick of dynamite and pretending that it makes us safe.