LONDON — In early October 2008, three weeks after the Lehman Brothers collapse, I met in Paris with leaders of the countries in the euro zone. Oblivious to the global dimension of the financial crisis, they took the view that if there was fallout for Europe, America would be to blame — so it would be for America to fix. I was unable to convince them that half of the bundled subprime-mortgage securities that were about to blow up had landed in Europe and that euro-area banks were, in fact, more highly leveraged than America’s.

Despite the subsequent decision of the Group of 20 in 2009 on the need for rules to supervise what is now a globally integrated financial system, world leaders have spent the last five years in retreat, resorting to unilateral actions that have made a mockery of global coordination. Already, we have forgotten the basic lesson of the crash: Global problems need global solutions. And because we failed to learn from the last crisis, the world’s bankers are carrying us toward the next one.

The economist David Miles, who sits on the monetary policy committee of the Bank of England, may exaggerate when he forecasts financial crises every seven years, but most of the problems that caused the 2008 crisis — excessive borrowing, shadow banking and reckless lending — have not gone away. Too-big-to-fail banks have not shrunk; they’ve grown bigger. Huge bonuses that encourage reckless risk-taking by bankers remain the norm. Meanwhile, shadow banking — investment and lending services by financial institutions that act like banks, but with less supervision — has expanded in value to $71 trillion, from $59 trillion in 2008.

Europe’s leaders aren’t the only ones with these blind spots. Emerging-market economies in Asia and Latin America have seen a 20 percent growth in their shadow-banking sectors. After 2009, Asian banks expanded their balance sheets three times faster than the largest global financial institutions, while adding only half as much capital.