In his piece, Jen hypothesizes another possibility that rising expectations of future currency appreciation attracts large capital inflows (I think he meant hot money) thus dampens central bank's hope that currency appreciation would reduce inflation pressure through the balance-of-payments channel.
One of the key structural forces of inflation in China, as is widely agreed, is the persistent and large rise in its official reserves, roughly half of which have, in recent years, been sterilised. What makes China's case rather remarkable is that China not only runs a large C/A surplus (which averaged 7.4% of GDP during 2005-07), but it has also received very large capital inflows. Official reserves grew sharply from 2002 (US$286 billion) to 2005 (US$819 billion), but really accelerated in 2007 (reserves increased by US$461 billion). What is perhaps even more remarkable is that, while China's C/A surplus has continued to expand, the growth (my emphasis) in net capital inflows in 2007 accounted for 59% of the total increase in reserves. To spell this out, China's massive C/A surplus last year of US$206 billion accounted for 'only' 41% of the increase in official reserves. We argue that much of these large capital inflows may have been motivated by the general expectation that the CNY would continue to appreciate against the dollar at a rapid pace, and that having a short USD/CNY exposure was a high-yield zero-risk investment. Thus, rather perversely, while Beijing's ultimate objective of bringing the value of the CNY more in line with the economic fundamentals should eventually lead to a more sustainable BoP position, the process of getting there is inflationary. In sum, while many have argued that the stronger CNY has helped China to contain inflation, we believe that precisely the opposite is the case.
Theoretically, the only way around this dilemma confronted by China is to have a maxi-revaluation in the CNY against the dollar of a size so large that few investors would believe that the CNY can appreciate further. This is the only effective way to halt the speculative capital inflows into China. The practical obstacle, however, is that it is not clear how big such a move in USD/CNY would have to be. Related to this question are the concepts of the 'fair value' and the 'equilibrium value' of USD/CNY. The former is the value of USD/CNY that is consistent with the underlying economic fundamentals (e.g., productivity, terms of trade, etc.), while the latter is the value of USD/CNY that will help to close China's BoP surplus. We believe that the current spot USD/CNY is already close to the 'fair value'. However, to close China's BoP surplus, USD/CNY would probably need to decline by a massive (50%?) amount. Would Beijing feel comfortable implementing a step revaluation in CNY from 7.00 to 3.50 in one go? We doubt it.
Second, Jen thinks the only solution to the inflation problem is a large one-time currency reevaluation. But there are many other policy possibilities.