But for how long? One day, the forces that turned the palest, thinnest of green shoots after the financial crisis into the second longest American economic expansion on record will change direction, igniting a new recession—for which the world is woefully unprepared. When that might happen is hard to say. Studies of American business cycles suggest that the economy is as likely to flip from growth to contraction early in the life of a boom as later on. Indeed, America has no records of an expansion lasting longer than a decade, though many countries do: Australia, Canada and the Netherlands have all enjoyed sustained growth lasting more than 20 years in recent memory. Yet all good things come to an end.
但这种好日子能维持多久？某天这股自经济危机后产生，将最微弱的经济复苏迹象转变成为美国经济历史上第二长的增长周期的力量，将会调转方向，引发一场新的衰退，而对于这一切，整个世界尚未准备好。这种情况何时会发生难以确定。对于美国经济周期的研究表明，这种经济上的从增长到衰退的掉头可能在刚刚开始繁荣的时候便发生。确实，美国经济历史上没有长于十年的经济增长阶段，但是许多其他国家却存在这种现象：澳大利亚、加拿大以及荷兰都曾在近现代有过超过 20 年的持续增长。然而好日子总归有结束的时候。
Though there is no settled view on what constitutes a global recession, worldwide slumps are usually marked out by a sharp slowdown in global growth and a decline in real gdp per person. Roughly speaking, there have been four global recessions since 1980: in the early 1980s, the early 1990s, in 2001, and in the crisis of 2007-08. Each was marked by a slowdown in gdp growth, a sharp decline in trade growth, and retrenchment in the financial sector. According to the Behavioural Finance and Financial Stability project at Harvard University, an average of four countries a year suffered a banking crisis between 1800 and 2016. From 1945 to 1975, when the global financial system was tightly controlled, most years were entirely free of banking crises. Since 1975, however, an average of 13 countries have found themselves in the throes of one each year. Since the 1970s, the deregulation of national banking systems and the lifting of constraints on the global flow of capital ushered in a new era of financial boom and bust. Re-regulation since 2009 has not fundamentally changed this picture. The current value of outstanding cross-border financial claims, at 35trn reached in 2008, but well above the 1998 level of $9trn.
尽管对于如何才能够得上是全球性的经济衰退尚未有定论，但是全球经济的萧条通常意味着全球经济增长的急剧下跌，以及个人实际 GDP 的下降。粗略地说，在 1980 年后，全球经济大约经历了四次衰退：在 1980 年代的早期，1990 年代的早期，在 2001 年，以及 2007-08 的经济危机。每次危机都存在着 GDP 增长的减缓，贸易增长的急剧下跌，以及经济行业的紧缩。依据哈佛大学 Behavioural Finance and Financial Stability 工程的研究成果，自 1800 年到 2016 年，平均每年都会有四个国家经历银行业危机。从 1945 年到 1975 年，当全球金融收到严格管制的时候，大部分年份都没有发生银行业危机。然而，自 1975 年后，平均每年都有 13 个国家忙于处理银行业危机。自 1970 年代以来，对于国家银行体系监管的减少以及对于国际件资本流动的限制的减弱，使得金融业迎来了一个繁荣和衰退并存的新时代。自 2009 年以来的新的监管政策并没有改变这一大形势。目前跨境金融的价值据称有 3 万亿美元（持续增加中），低于 2008 年曾达到的 3.5 万亿美元的高度，但也远高于 1998 年的 9000 亿美元。
