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.

但這種好日子能維持多久？某天這股自經濟危機后產生，將最微弱的經濟復蘇跡象轉變成為美國經濟歷史上第二長的增長周期的力量，將會調轉方向，引發(fā)一場新的衰退，而對于這一切，整個世界尚未準備好。這種情況何時會發(fā)生難以確定。對于美國經濟周期的研究表明，這種經濟上的從增長到衰退的掉頭可能在剛剛開始繁榮的時候便發(fā)生。確實，美國經濟歷史上沒有長于十年的經濟增長階段，但是許多其他國家卻存在這種現象：澳大利亞、加拿大以及荷蘭都曾在近現代有過超過 20 年的持續(xù)增長。然而好日子總歸有結束的時候。

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.

盡管對于如何才能夠得上是全球性的經濟衰退尚未有定論，但是全球經濟的蕭條通常意味著全球經濟增長的急劇下跌，以及個人實際 GDP 的下降。粗略地說，在 1980 年后，全球經濟大約經歷了四次衰退：在 1980 年代的早期，1990 年代的早期，在 2001 年，以及 2007-08 的經濟危機。每次危機都存在著 GDP 增長的減緩，貿易增長的急劇下跌，以及經濟行業(yè)的緊縮。依據哈佛大學 Behavioural Finance and Financial Stability 工程的研究成果，自 1800 年到 2016 年，平均每年都會有四個國家經歷銀行業(yè)危機。從 1945 年到 1975 年，當全球金融收到嚴格管制的時候，大部分年份都沒有發(fā)生銀行業(yè)危機。然而，自 1975 年后，平均每年都有 13 個國家忙于處理銀行業(yè)危機。自 1970 年代以來，對于國家銀行體系監(jiān)管的減少以及對于國際件資本流動的限制的減弱，使得金融業(yè)迎來了一個繁榮和衰退并存的新時代。自 2009 年以來的新的監(jiān)管政策并沒有改變這一大形勢。目前跨境金融的價值據稱有 3 萬億美元（持續(xù)增加中），低于 2008 年曾達到的 3.5 萬億美元的高度，但也遠高于 1998 年的 9000 億美元。