Exporting Europe’s Stagnation
By Paul Krugman

Watch that plunging euro! Actually, it’s good news for Europe. European growth numbers have been better lately, and the weak euro — which makes EZ manufacturing and other tradables more competitive — is surely a large part of the explanation. Not so good for Japan or the US. But how should we think about this?

It’s more or less standard international macro that with high capital mobility and floating exchange rates, demand shocks in any one country or region will be “shared” with other countries. If you have exceptionally strong demand, your currency will rise, crimping your own growth while boosting growth abroad; if you have exceptionally weak demand, you will get partial compensation via a weaker currency that helps net exports. Such effects can be offset with interest rate changes if you’re not at the zero almost lower bound, but we are.

But how much of a demand shock is shared? I argued about a month ago that it depends on the extent to which the shock is perceived as temporary versus permanent. In an idealized world permanent shocks should be fully shared — that is, permanently weak demand in Europe should hurt the United States just as much as it does Europe.

So, can we say anything about how the recent move in the euro fits into this story? One way, I’d suggest, is to ask how much of the move can be explained by changes in the real interest differential with the United States. US real 10-year rates are about the same as they were in the spring of 2014; German real rates at similar maturities (which I use as the comparable safe asset) have fallen from about 0 to minus 0.9. If people expected the euro/dollar rate to return to long-term normal a decade from now, this would imply a 9 percent decline right now.

What we actually see is almost three times that move, suggesting that the main driver here is the perception of permanent, or at any rate very long term European weakness. And that’s a situation in which Europe’s weakness will be largely shared with the rest of the world — Europe will have its fall cushioned by trade surpluses, but the rest of us will be dragged down by the counterpart deficits.

Now, this is not how most analysts approach the problem. They make a forecast for the exchange rate, then run this through some set of trade elasticities to get the effects on trade and hence on GDP. Such estimates currently indicate that the dollar will be a moderate-sized drag on US recovery, but no more. What the economic logic says, however, is that if that’s really true, the dollar will just keep heading higher until the drag gets less moderate.

弱勢歐元…重擊全球貿易

歐元跌得真是急！其實這對歐洲是好消息。歐洲近來成長數據改善，弱勢歐元當然是一大原因，因為歐元貶值使歐元區製造的產品及其他貿易財更有競爭力。但對日本或美國而言，這就不太妙了。我們應該如何看待此事？

這或多或少可稱作是標準的國際總體經濟事件。在資本流動性高且匯率浮動的情況下，任一國家或地區境內出現的需求衝擊，也將與其他國家「共享」。若某國的需求異常地強，貨幣會升值，阻礙本國的成長，但卻會推升外國的成長；若某國的需求異常地弱，可經由貨幣貶值助長淨出口，而獲得局部補償。這種效應可藉利率調整來抵銷，但前提是利率不能位於幾近於零的底限，但目前利率水準卻是如此。

需求衝擊的外溢效應會有多大？這要看衝擊被視為暫時性、而非永久性的程度而定。理想上，永久性的衝擊理應是充分共享的－也就是說，歐洲的需求若是長久疲軟，對美國的傷害將不下於對歐洲的傷害。

那麼，歐元近來的跌勢符合這種情況嗎？我建議換一種方式來問，就是這波跌勢有多大程度是因為與美國的實質利率差距造成的？目前美國的10年期公債實質利率，與2014年春季的水準大致相同；德國同年期公債（我用它來作為可相提並論的安全資產）的實質利率，則已從零降到負0.9%。假如人們預期十年後歐元兌美元匯率會回歸長期正常水準，那就暗示此刻跌9%。但我們實際看到的，卻是將近此數三倍的跌幅，這顯示歐元貶值的主要驅動力是對歐洲永久（或至少長期）疲軟的認知。正是在這種情況下，世界其他地區將會普遍感染到歐洲的疲弱。歐洲的貿易順差可緩和經濟跌跤的衝擊，但其他國家都將被相對貿易逆差拖累。

大多數分析師探討此問題時，並不是這麼看的。他們做匯率預測，然後套用某種貿易彈性估計，得到對貿易乃至於國內生產毛額（GDP）的影響數字。這些估計數字目前顯示，美元升值對美國的復甦只會產生溫和影響，僅止於此。經濟邏輯卻顯示，若真如此，美元就會持續走高，直到對復甦的影響變得較不溫和為止。

原文參照：
http://krugman.blogs.nytimes.com/2015/03/11/exporting-europes-stagnation/

2015-03-13．經濟日報．A7．國際．編譯湯淑君