中国是石油进口国，而且自2002年初以来原油价格乘以五了。中国进口的其他商品（例如铜）的价格也在过去几年激增。为什么这些没有在中国的经常账户盈余上留下痕迹？这是奇事一。
一个国家的进口往往随国内经济增长而增长，而且出口的增长和世界其他地方的增长保持一致。以此逻辑，中国（增长得比那些购买中国商品的国家快）的经常帐户应该有点衰退。为什么出现相反的结果呢？这是奇事二。
一个国家的经常帐户盈余代表国内储蓄相对当地投资过剩。最近几年，中国的本地投资兴旺。然而，经常帐并没有变坏。中国是怎么处理的呢？这是奇事三。
经济学家曾以似是而非的臆测寻求分别解开这些谜团。然而，曾在1991至2001年担任国际货币基金会首席经济学家、如今是华盛顿彼得森国际经济研究所（Peterson Institute for International Economics）高级研究员的穆萨（Michael Mussa）认为，可能有一个解释可以解开所有这些谜团。
穆萨在最近的研究中把中国的收支平衡视为一种货币现象，一种适合于挂钩货币的国家的办法。人民币出于实际目的，仍然和美元绑在一起，自从2005年7月的小幅升值以来仅上涨9%。
关键点是：假定中国居民对购买力（货币量和银行存款）的需求随经济扩张上涨，那么中国货币当局就有压力制造更多的钱。但基本货币供应量是中央银行的责任，必须与国内和国外资产相配合。那么央行应该升哪个呢？
如果它从银行购买国内资产（政府债券），它可以给予人们他们想要的钱。这是在发达国家发生的事情，而且当经济增长超过潜力时，他们得到了通胀。但在快速发展的发展中国家（最突出的是中国），央行的办法是购买外国资产，即美国债券，以防止货币的升值。由于由此产生的基本货币增长可能触发通胀，伴随的做法是"冲销（sterilization）"：央行出售本地债券，拒绝给予人们想要的购买力。
穆萨认为这就是中国发生的事情。穆萨表示，中国人民银行在2003年年底到2006年期间增加了价值5.5万亿元人民币的外汇储备。在此期间，它削减净国内资产3万亿元人民币。这样，中国居民就孤立无援了。他们别无选择，只能期待存足够的钱以获得他们想要的购买力。
居民获钱的另一种办法是接入外国资本流。在美国，次贷借款人可以从德国银行获得资本，但中国不是这样，中国的金融体系更为封闭。
银行信贷可以把外国资本导入当地借款人。在中国，大型国有企业和那些生产可出口产品的公司更容易获得银行信贷。因此它们狂热地投资。
净结果是投资高，储蓄更高，低消费，有超过1.4万亿的外汇储备，尽管进口商品价格上涨，经常帐仍然涨鼓鼓的。所有这些都同时发生，因为央行在压制人们对货币的需求。
穆萨的分析止于2006年。此后发生了什么？似乎更是如此。
第三季度的GDP增长率为11.5%，10月的通胀率达6.5%，可预计中国人民银行吝啬基本货币。
在今年的上半年，尽管名义GDP增长16%，外汇储备上涨了20%，但基本货币扩张6%。除非中国允许人民币升值速度明显加快，回避大量堆积外汇储备的需要，否则这将是人们储蓄更多的好机会，而且2008年经常账户盈余将进一步膨胀。
或者中国经济将面临硬着陆，对货币的需求将回落。对中国和世界而言，这是更加痛苦的事。
如果你觉得布什政府对付中国经历了艰难时刻，那白宫的下一位主人可能更艰难。（作者 Andy Mukherjee）
Money Is Key to Solving Many of China's Puzzles: Andy Mukherjee
By Andy Mukherjee
Nov. 15 (Bloomberg) -- China is an oil importer and crude prices have quintupled since early 2002.
Prices of other commodities imported by China -- such as copper -- have shot up, too, in the past few years.
Why have they failed to make any dent into China's current- account surplus, which may widen to a staggering 12 percent of gross domestic product this year?
That's Mystery No. 1.
A country's imports tend to increase in tandem with its domestic economy, and exports rise in line with expansion in the rest of the world. By that logic, China, growing faster than any major economy that buys Chinese goods, ought to have seen some deterioration in its current account.
How did it end up with the opposite outcome?
That's Mystery No. 2.
The current-account surplus of a country represents an excess of domestic savings over local investments. The latter have boomed in China in recent years. And yet, the current account hasn't worsened. How has China managed to engineer such a rise in national thrift, which by now must equal almost half of its GDP, to finance its growing hunger for investments?
That's Mystery No. 3.
Economists have advanced plausible hypotheses that seek to solve each of these mysteries separately.
However, there might be a single explanation for all these riddles, says Michael Mussa, chief economist at the International Monetary Fund from 1991 to 2001 and now a senior fellow at the Peterson Institute for International Economics in Washington.
Monetary Approach
In a recent study, Mussa looks at China's balance of payments as a monetary phenomenon, an approach ideally suited to countries with pegged currencies, and the Chinese yuan, for all practical purposes, is still tied to the U.S. dollar, having risen just 9 percent since a small revaluation in July 2005.
The key idea is this: Assuming Chinese residents' demand for purchasing power -- the sum of currency and bank deposits -- is rising in tandem with economic expansion, there's growing pressure on the Chinese monetary authority to create more money.
But base money -- the sum of currency and reserves that banks keep with the monetary authority -- is the central bank's liability and must be matched by its domestic and foreign assets.
So which of the two should the central bank increase?
If it buys domestic assets -- government bonds -- from banks, it gives people the money they want. This is what happens in developed countries; and this is how they get inflation when the economy grows above its potential.
Suppressing Monetary Base
But in fast-growing developing countries, most notably China, the approach of the central bank is to buy foreign assets -- say, U.S. Treasuries -- to prevent appreciation in the currency. Since the resultant growth in base money may spark inflation, an attendant practice is ``sterilization'': The central bank sells local bonds to deny people the purchasing power they want.
This is what Mussa says has happened in China.
The People's Bank of China added the equivalent of 5.5 trillion yuan ($740 billion) to its foreign reserves between the end of 2003 and 2006. In this period, it whittled down its net domestic assets by 3 trillion yuan, Mussa says.
This left Chinese residents high and dry. They had no option except to save more to get the purchasing power they want.
High Savings, Investments
The only other alternative for residents to acquire money was by tapping foreign capital flows. But unlike in the U.S., where a subprime-mortgage borrower can access capital from a German bank (and land it in trouble), China's financial system is much more closed, Mussa says.
Bank credit, which can channel foreign capital to local borrowers, is more readily available in China to large state- owned enterprises and to those companies that make exportable goods, which are quite profitable because of a favorable exchange rate. So they invest with abandon.
The net result is high investments, even higher savings, low consumption, more than $1.4 trillion in foreign-exchange reserves and a bloated current-account surplus despite a rise in the price of imported commodities. All of this is happening simultaneously because the central bank is repressing people's demand for money.
Mussa's analysis stops in 2006. What has been happening since then? More of the same, it seems.
With GDP growing at an annual pace of 11.5 percent in the third quarter and the inflation rate rising in October to 6.5 percent, the highest in a decade, the People's Bank of China is predictably stingy with base money.
Hard Landing?
In the first half of this year, base money expansion was 6 percent even as nominal GDP grew 16 percent and foreign-exchange reserves jumped by a fifth. Unless China allows significantly faster appreciation in the yuan, obviating the need for large accretion in foreign reserves, there's a good chance that people will save even more and the current-account surplus will bloat even further in 2008.
Either that or China's economy will have a hard landing and demand for money will ebb. That will be more painful to both China and the world.
If you think George W. Bush's administration had a tough time dealing with China, the next occupant of the White House may have it worse.
(Andy Mukherjee is a Bloomberg News columnist. The opinions expressed are his own.)
To contact the writer of this column: Andy Mukherjee in Singapore at amukherjee@bloomberg.net .
