In the summer and fall of last year, the Greek financial crisis tore at the seams of the global economy. Having run up a debt that it would never be able to repay, the country faced a number of potential outcomes, all unpleasant. Efforts to slash spending spurred riots in the streets of Athens, while threats of default rattled global financial markets. Many economists argued that Greece should leave the euro zone and devalue its currency, a move that would in theory help the economy grow. “Make no mistake: an orderly euro exit will be hard,” wrote New York University economist Nouriel Roubini in the Financial Times. “But watching the slow disorderly implosion of the Greek economy and society will be much worse.”
No one was sure exactly how the scenario would play out, though. Fear spread that if Greece were to abandon the euro, Spain and Italy might do the same, weakening the central bond of the European Union. Yet the Economist opined that the crisis would “bring more fiscal-policy control from Brussels, turning the euro zone into a more politically integrated club.” From these consequences would come yet further-flung effects. Migrants heading into the European Union might shift their travel patterns into a newly affordable Greece. A drop in tourism could limit the spread of infectious disease. Altered trade routes could disrupt native ecosystems. The question itself is simple—Should Greece drop the euro?—but the potential fallout is so far-reaching and complex that even the world’s sharpest minds found themselves unable to grasp all the permutations.