It has been a busy year for trade economists. The US and China have exchanged tariff increases, and the UK is deciding how to remodel its trading arrangements with the EU and the rest of the world after Brexit.

There is wider evidence of a backlash against free trade. Surveys show hardening public attitudes towards it in rich countries, particularly the US. While appreciating its benefits to consumers, Americans also increasingly blame free trade for reducing wages and destroying jobs. Fewer trade deals are being signed, ending an upwards trend that had lasted for decades during an unprecedented integration of the world economy.

Changes in trade policies, and the public attitudes that help drive them, do matter. It was long thought that more trade was inevitable, as transportation costs fell and technological improvements smoothed the way. But research has shown that policy changes and international co-operation played a crucial role. Globalisation was a choice, hence it could be reversed — at least partially — if rich countries decided to.