‘TRADITION and duty; sacrifice and pain”, not perhaps the words we normally associate with the left, but a pithy summation of the meaning of the “climate emergency” that the First Minister Nicola Sturgeon announced at the weekend, and which will be declared by Jeremy Corbyn today in Westminster.

The phrase comes from Roger Hallam, one of the leading figures in the Extinction Rebellion movement that has had such a dramatic impact on our political classes. He coined it during an interview by the Labour activist and columnist Owen Jones. It is what is meant by “putting the nation on a war footing”, something the former Labour leader Ed Miliband called for yesterday.

Cutting carbon emissions by 50 per cent in 10 years will certainly involve a great deal of sacrifice and pain. As for “tradition and duty”, that is the moral state of mind Mr Hallam believes is needed to mobilise our feather-bedded electorates into recognising their obligations to biodiversity and keeping the planet habitable for future generations.

Mr Hallam surprised Mr Jones by dismissing socialism as just as environmentally unsound as capitalism. This because social democracy is based on the idea that material living standards can be improved for the many not just the few. Mr Hallam insists there has to be “a reduction in living standards” for the many as well as the few.

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Extinction Rebellion’s proposal to cut C02 emissions to net zero by 2025 would mean such a radical change to our western lifestyles that it is hard to comprehend. For a start, if Ms Sturgeon is serious, it would involve shutting down Scotland’s oil and gas industry, which employs 100,000 people. Climate emergency means sending 38 million cars to the scrap heap in the next six years, grounding all aircraft and disconnecting millions of gasboilers. Food prices would increase as cheap imports are curbed along with the diesel-powered trucks that transport them.

It’s doable, perhaps, if this were a real war and the climate an identifiable enemy. But in peace-time, politicians are simply unable to demand this kind of sacrifice from the public because they know they’d be thrown out of office. Climate emergency, if it means more than just words, represents a profound challenge, not only to politicians, but to voters too. Indeed, a war economy is arguably incompatible with democracy. In wartime, governments acquire special powers to introduce rationing, seize property, direct industry and draft the unwilling into the fight.

Moreover, real wars are generally good for economic growth because they involve boosting industrial production. It was rearmament for the Second World War that finally dragged America and the West out of the Great Depression. A climate war would involve the reverse: shutting down large sectors of industry. “De-growth” as Extinction Rebellion calls it, would almost certainly mean a recession and a lot of people out of work, which is a difficult sell to put it mildly. A real climate war would make the financial crash seem like a holiday in Spain.

So the question has to be raised: are our politicians remotely serious? Or is this all just political greenwash that’ll be forgotten as soon as the news agenda turns back to Brexit? Last month, the SNP Government voted down a Green Party MSP’s motion calling for precisely the climate emergency that the First Minister is now advocating. As recently as two years ago, Mr Corbyn appeared to be talking about coal mines reopening. All politicians want economic growth. I can’t see Ms Sturgeon commissioning a De-growth Commission Report from Andrew Wilson any time soon.

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Most politicians on the left are proposing a Green New Deal, which involves creating thousands of jobs building electric cars, fast trains and bigger and better wind turbines. This all makes sound economic sense, and phasing out the internal combustion engine is long overdue. But Mr Hallam is sceptical. Any new deal worth the name involves increasing living standards, not reducing them. True climate warriors fear that Labour’s Green Deal is at best an attempt to have it both ways, at worst a diversion.

The best that politicians have been able to offer hitherto is a net zero carbon economy, which the Scottish Government has promised to achieve by 2050. The Committee on Climate Change is expected to call tomorrow for the UK to come into line with Scotland, which is a step forward. But this is still 20 years too late, according to the UN International Climate Change Panel, which warned last year that urgent action is needed to prevent global warming rocketing beyond 1.5C.

Yet the UK is one of the world leaders in cutting carbon. Greenhouse gases are down 40 per cent on 1990 levels, even though the economy has grown by a third. The big reduction in emissions has come from closing coal-powered stations like Longannet. But as every right-wing politician and commentator has been saying throughout Extinction Rebellion fortnight, China is opening a new coal-powered station almost every week. India, America and much of South-east Asia are going for coal, which could negate efforts here.

Arguably, much of China’s emissions are ours too because we have outsourced the production of so many of our consumer goods, from phones to clothes, by cheap and dirty manufacturing. We should perhaps be planning to “reshore” much of this to the UK and Europe. But barring Chinese consumer goods, on the grounds that we should be making them more expensively here, would be hard to reconcile with free trade. The Chinese government might regard carbon reshoring as a kind of protectionism.

So the war on climate change can’t take place in one country. It needs an unprecedented international effort. It can be done, as the international community showed when it closed the hole in the ozone layer that emerged in the 1990s. But addressing climate change is on another level entirely. And it needs a degree of realism. Politicians are sincere, but they must avoid inflated rhetoric and making claims they know they can’t deliver. Once you declare a war, you have to fight it to victory.