The global economy is entering unfamiliar territory. After a decade of worries about inadequate demand and spending power in the aftermath of the global financial crisis, signs of insufficient supply are now emerging. A lack of goods, services and people means that red-hot demand is increasingly met slowly or not at all.

There are already signs that supply bottlenecks may lead to nasty surprises which could upset the post-pandemic recovery. Nowhere are shortages more acute than in America. Consumer spending is growing by over 10% at an annual rate, as people put to work the $2 trillion-plus of extra savings accumulated in the past year. More stimulus is still being doled out.

The boom is creating two kinds of bottleneck. The first relates to supply chains. There are shortages of everything from timber to semiconductors. The cost of shipping goods from China to America has tripled. Companies have not reported supplier delays this severe in decades. In the past year many firms have cut their investment in logistics. Lockdowns have left some container ships stranded. Companies are trying to go from 0 to 60 and it shows.

The second kind of bottleneck is in labor markets. In April America created only 266,000 jobs, many fewer than the 1 million or more that had been expected. Yet job vacancies are at all-time highs, and so firms are struggling to fill positions. Economists argue over whether generous unemployment benefits are giving people a reason not to look for work.

As booming demand runs up against tight supply, inflation is in the spotlight. In April American consumer pricesrose by 4.2% year on year, up from 2.6% in March. This partly reflects "base effects": Oil prices are only as high as they were in 2019, but 272% higher than in April 2020. It also reflects a genuine underlying rise in global prices. China's factory-gate prices are rising at the fastest rate in over three years.

Central banks insist that their maximal stimulus must continue for fear of jeopardizing thenascent recovery. Jerome Powell, the Federal Reserve chairman, sees little reason to worry. The Fed will tolerate somewhat above-target inflation for a bit, in part because it expects prices soon to fall back.

Yet this approach carries dangers. One is that inflation fades slowly. The supply bottlenecks of the early phase of the pandemic in 2020 cleared fast, but there is no guarantee this will happen now. Inflation expectations may also rise if people come to believe that central banks will act slowly. Many companies are now discussing inflation with their investors. Bond-market traders think the Fed will be forced to act sooner than it wants.

This points to the danger that sharp rate rises rock markets. So far the main event has been a sell-off in tech stocks, which is manageable. Banks are well capitalized. Yet the recent implosions of Archegos, a hedge fund, and Greensill Capital, a finance firm, are a reminder of the hidden leverage in a financial system that has come to depend on low interest rates.

The post-pandemic boom may not always be exciting for the right reasons.