中国一位顶尖的经济学家发出警告，全球已陷入“美元陷阱”——美国的贸易伙伴国既缺乏可替代美元的货币选择，也无法阻止美联储（Federal Reserve）印发更多美元。

    这意味着大量持有美元资产的国家——如中国，该国大约3万亿美元的外汇储备中大部分是美元资产——只能坐视资产贬值。也不能轻易地进行货币多元化，因为这可能加速美元资产的缩水。

    现行国际货币体系“既缺乏稳定性，也缺乏公平性”，中国国际经济交流中心的经济学家徐洪才写道。

    徐洪才的这番言论见报，时间正是二十国集团（G-20）财长会议于3月31日在南京召开前。二十国集团财长将讨论如何取代当前以美元为中心的国际货币体系——这个问题多年来一直困扰着经济学家和政策制定者们，随着中国的崛起，这个问题变得更为紧迫。

    此次会议召开之际，美元指数正徘徊于近期低点附近，原因是美国经济困顿以及美国联邦储备委员会的扩张性货币政策。虽然日本遭受了大灾，但过去一年美元/日元走低；即便是欧洲可能迎来新一轮耗资巨大、存在政治争议的援助计划，美元/欧元也未能走高。

    徐洪才在文章中建议，应建立一个由国际货币基金组织（International Monetary Fund）等类似机构监管的多储备货币体系。他指出，（当一种储备货币贬值时，）国际货币基金组织可以发出警告，迫使相关国家采取干预措施，稳定币值。路透社（Reuters）认为，这一提案不太可能得到西方人的认可，西方人更赞成已实行几十年的自由浮动汇率体系。

    当然，要解决这个已延续几十年的问题绝非易事。但《华尔街日报》(Wall Street Journal)的一篇报道称，此次会议自由交换意见的氛围可能不如以往。中国官员对于美元贬值和严格管制人民币汇率的话题非常敏感，已敦促参与各方不要谈论太平洋两岸热议的汇率问题。

    虽然这似乎是个好办法，但沉默并不能让这个问题自动消失。

    A top Chinese economist warned that the world has fallen into a "dollar trap," as U.S. trading partners lack an alternative to the greenback and can't prevent the Federal Reserve from printing more money.

    The arrangement means big holders of dollars – such as China, which holds some $3 trillion of foreign exchange reserves, mostly in dollars – must sit idly by and watch as the value of their holdings erode. They can't lightly diversify out of dollars at the risk of accelerating the erosion.

    The setup "lacks both stability and fairness," wrote Xu Hongcai, an economist at the China Center for International Economic Exchanges.

    He made the remarks in a paper published ahead of Thursday's meeting of G-20 finance ministers in Nanjing. They will discuss what might replace the current dollar-centric system – a subject that has vexed economists and policymakers for years and has grown more pressing with the rise of China.

    The meeting comes at a time when the dollar index is near its recent lows, thanks to the stumbles of the U.S. economy and the expansive monetary policy of the Fed. The dollar is down over the past year against the yen in spite of a massive disaster in Japan, and has failed to appreciate against the euro even as the Continent stumbles toward another spring of costly, politically divisive bailouts.

    Xu, for his part, suggests moving toward a system of multiple reserve currencies overseen in part by the likes of the International Monetary Fund. He says the IMF could issue alerts that would prompt countries to intervene to hold the value of their currencies steady. Reuters notes that the proposal isn't likely to pass muster with Westerners who favor the free-floating system that has been in place for decades.

    There is no easy answer to a problem that has built up over decades, of course. But a report in the Wall Street Journal says the session promises to be even less of a free-flowing exchange of ideas than usual. Chinese officials are so sensitive on the subject of the weakening dollar and their tight control of their own currency, the yuan, that they have urged participants not to discuss the exchange rate issue that has been so heatedly debated on both sides of the Pacific.

    But as appealing as that may sound, giving this problem the silent treatment is not going to make it go away.