The global fall-out from a long-anticipated Greek government default alone should be small and manageable, even if it takes the form of a “disorderly” default without the agreement of private creditors or the other euro-zone members. Nonetheless, there are at least two ways in which the crisis could escalate into something much more serious: increased risk of default in other, much larger, peripheral economies, and the prospect that Greece becomes the first country to abandon the euro altogether.