On paper, this cap-and-trade approach is an intelligent and effective way of rationing carbon and producing a price for CO2. A cap is set on the amount of greenhouse gases that can be emitted by 11,000 power stations and factories in 28 member states. EU Allowance Units (EUAs) are then auctioned off or allocated for free, and can be traded on the open market. The cap is supposed to be lowered over time. If a factory or power station exceed its allowance, it purchases EUAs on the ETS market. Conversely, if it produces less CO2, it can sell leftover credits. The idea is to find the most cost-effective way of reducing emissions without significant government intervention.

The ETS was undermined from the beginning by an over-allocation of allowances, the number of which is essentially a political decision. In the Brussels horse-trading, each country got more than its share. Having started in 2005 with carbon prices of €10-15 per ton, the market price fell briefly to zero in 2007. The system was further undermined by the recession of 2008-09, which saw a substantial fall in economic activity. This meant that the already comfortable supply of EUAs became overwhelming.

The ETS depends on the EU having the will — and indeed the information — to ration EUAs over time and in ever-changing economic circumstances. So far it has failed to do so. The only country that regularly checks installations to ensure they are actually complying with regulations is, you guessed it, the UK. And even the UK checks only 1 per cent of qualifying sites.

The ETS has raised costs for European industry while failing to produce a serious carbon price which would support low- carbon technology and make fossil fuels uneconomic. To be effective, the carbon price should be of the order of €75 per ton; the current EUA price is €8 per ton. If the EU, composed of 28 advanced economies with reasonably high legal standards, is unable to operate its own system effectively, it is clear that a global system is doomed to fail.

The real challenge for the COPsters comes from China, India and other large developing countries. China is the world’s largest user of energy, 90 per cent of which is fossil-fuel, two- thirds of it coal. China accounts for half of the world’s annual coal burn. It is also the world’s largest emitter of CO2: 24 per cent of the global total in 2014. Chinese economic development plans call for significant increases in energy consumption, including coal, between now and 2030. The proportion of coal in the mix will fall, but only from 66 per cent to 62 per cent in the next ten years; and it will rise in absolute terms. China will increase its reliance on renewables, building on hydro as well as its low-cost production of wind turbines and solar panels; but the overall consumption of coal, oil and gas will continue to grow for the foreseeable future.