‘Economists have long argued that the most efficient way to curb global warming is to put a price on the greenhouse-gas emissions that cause it. A total of 41 OECD and G20 governments have announced either a carbon tax or a cap-and-trade scheme, or both. Add state and local schemes, and they cover 15% of the world’s emissions, up from 4% in 2010. Voters concerned about climate change are egging them on. So, too, are corporate bosses. More firms are imposing such pricing on themselves, even in places where policymakers are dragging their feet,’ (‘Low-carb diet’, The Economist 13th January 2018, p55).