Matt Ridley: The Paris climate treaty is weak, so why do climate activists defend it?

President Trump will decide shortly whether to pull the US out of the Paris agreement on climate change. By all accounts, his instincts and his campaign promises encourage him to do so while his daughter Ivanka and his secretary of state Rex Tillerson want him not to. He has already started rolling back the “clean power plan”, which was Barack Obama’s way of meeting America’s commitment under the Paris agreement.

If he does pull out, or send the agreement to the Senate for ratification on the grounds that it is a “treaty” — something Obama took great pains to try to deny so that he would not have to send it to the Senate — there will be a fresh paroxysm of rage among his critics. Climate scepticism is high among reasons that the left hates Trump. By contrast, it is one of the few things on which I half agree with him.

I am not quite sure why his critics mind so much. Indeed, if I were one of those who thought climate change the biggest threat to humankind bar none, then I would be far more critical of the Paris agreement than I actually am. I would rail against the fact that it is a futile gesture, neither legally binding enough to be enforceable, nor of sufficient scale to make a difference to climate change. It’s those people who most worry about global warming who should be most critical of Paris.

To understand why, wind the clock back eight years to the Copenhagen climate conference in 2009, where world leaders were humiliated by their inability to reach agreement on a replacement for the Kyoto treaty of 1997. Kyoto’s fundamental flaw was beyond remedy: it put a heavy burden on the developed world, while rapidly growing countries, such as China, were unaffected. After Copenhagen the whole Kyoto process unwound. The US failed to ratify, Japan said it would never commit to a similar treaty in the future, Russia rejected the second round of commitments and Canada pulled out completely.

Determined not to repeat the Copenhagen fiasco, the climatocracy dominated by the United Nations, the European Union and the green NGOs set about building a new approach. In 2011, at Durban, they got world leaders to agree an EU plan to put in place by 2015 a legally binding treaty that would apply to the whole world and come into force by 2020. Connie Hedegaard, European commissioner for climate action, boasted that “the EU has achieved its key goal for the Durban climate conference” of agreeing to a “roadmap towards a new legal framework by 2015”.

But others were worried. Greenpeace observed that “the Durban Platform still includes wording that could be exploited by the US and its allies to push a voluntary rather than binding approach, and risks locking in the current inadequate level of carbon cuts for a decade”.

So it was clear that the 2015 Paris treaty was to be legally binding, not voluntary, and extreme, not modest, or it would be a failure. In November of that year, as Paris approached, this was reiterated repeatedly. “The Paris agreement must be an international legally binding agreement,” said the EU’s spokesman. The French foreign minister, Laurent Fabius, even rebuked John Kerry, the US secretary of state, for casting doubt on whether a legally binding treaty was possible. Mr Kerry was “confused”, he said.

However, Mr Kerry was right, and during the Paris meeting it became clear that no such agreement was possible. Instead of admitting another failure, the envirocrats decided to change tack: they abandoned any pretence of a legally binding agreement, called for voluntary offers of emission reduction, but covered this all up with a full-volume declaration of victory. When I pointed out the volte-face in a speech in the House of Lords, I was told by my own front bench that only North Korea agreed with me. Said the minister: “If it really was, as he perhaps implies, just a piece of paper and not worth the paper it is written on, why was it so hard an agreement to reach?” I do not follow this logic.

Yet not only was the Paris agreement not legally binding, it was also deeply impractical. The intended nationally determined contributions (INDCs) that each country offered turned out to be feeble. In a peer-reviewed paper, the economist Bjorn Lomborg calculated how much the pledges would reduce warming, using standard models and generous assumptions about how quickly the reductions would be achieved and how long they would be sustained.

He found that all the promises made by the US, China, the EU and the rest of the world, if implemented from the early 2000s to 2030, and then sustained through the rest of the century, would reduce the expected rise in global temperature by only 0.17°C in the year 2100. That is to say, instead of rising by 2, 3 or 4 degrees or so by the time our great grandchildren are adults, world average temperature would rise by 1.83, 2.83 or 3.83 degrees. Lomborg put it this way: “Current climate policy promises will do little to stabilise the climate and their impact will be undetectable for many decades”. A different study by scientists at MIT came to similar conclusions. The INDCs add up to the square root of zilch.

However, and this is the crucial point, Lomborg also points out this invisible achievement would come at a staggering cost, somewhere between $1 trillion and $2 trillion a year: “Paying $100 trillion for no good is not a good deal”. Who could disagree? Lomborg wants Trump to can the Paris agreement, which he rightly judges to be a feelgood gesture that distracts attention from aggressive research into low-emitting, cost-effective energy technologies, which is the only realistic way to reduce fossil fuel consumption.

Thus Paris embodies precisely what the green movement worried about after Copenhagen: that a weak and non-binding agreement would be worse than futile. Yet the disastrous Kyoto story is repeating itself; adherence to Paris has become a totem of global determination to tackle climate change while the agreement seems purpose-built to prevent the very economic sophistication on which any low-carbon future depends.

Britain, meanwhile, remains the only major economy legally bound by statute to reducing carbon dioxide emissions by its 2008 Climate Act: "The Climate Change Act requires the government to set legally-binding ‘carbon budgets’."

Matt Ridley, a member of the British House of Lords, is an acclaimed author who blogs at www.rationaloptimist.com.