Authored by Mohamed El-Erian via Project Syndicate,

The singular issue of Brexit has consumed the United Kingdom for two and a half years. The “if,” “how,” and “when” of the country’s withdrawal from the European Union, after decades of membership, has understandably dominated news coverage, and sidelined almost every other policy debate. Lost in the mix, for example, has been any serious discussion of how the UK should boost productivity and competitiveness at a time of global economic and financial fluidity.

At the same time, the rest of the world’s interest in Brexit has understandably waned. The UK’s negotiations with the EU have dragged on through multiple déjà vu moments, and the consensus is that the economic fallout will be felt far more acutely in Britain than in the EU, let alone in countries elsewhere.

Still, the rest of the world is facing profound challenges of its own. Political and economic systems are undergoing far-reaching structural changes, many of them driven by technology, trade, climate change, high inequality, and mounting political anger.

In addressing these issues, policymakers around the world would do well to heed the lessons of the UK’s Brexit experience.

When Britons voted by a margin of 51.9% to 48.1% to leave the EU, the decision came as a shock to experts, pundits, and Conservative and Labour Party leaders alike. They had underappreciated the role of “identity” as a driving force behind the June 2016 referendum. But now, voters’ deeply held ideas about identity, whether real or perceived, can no longer be dismissed. Though today’s disruptive politics are fueled by economic disappointment and frustration, identity is the tip of the spear. It has exposed and deepened political and social divisions that are as uncomfortable as they are intractable.

Experts also predicted that the UK economy would suffer an immediate and significant fall in output following the 2016 referendum. In the event, they misunderstood the dynamics of what economists call a “sudden stop” – that is, abrupt, catastrophic dysfunction in a key sector of the economy. A perfect example is the 2008 global financial crisis, when financial markets seized up as a result of operational dislocations and a loss of mutual confidence in the payments and settlement system.

Brexit was different. Because you cannot replace something with nothing, there was no immediate break in British-EU trade. In the absence of clarity on what type of Brexit would ultimately materialize, the economic relationship simply continued “as is,” and an immediate disruption was averted.

It turns out that when making macroeconomic and market projections for Brexit so far, “short versus long” has been more important than “soft versus hard” (with “hard” referring to the UK’s full, and most likely disorderly, withdrawal from the European single market and customs union). The question is not whether the UK will face a considerable economic reckoning, but when.

Nonetheless, the UK economy is already...