保罗·克鲁格曼最近在博客上发表文章计算了中国重商主义的宏观经济效果。他认为中国降低了世界其它国家的GDP约1.4个百分点。他的逻辑是IMF统计中国的出口顺差占世界GDP的0.9个百分点，抵消了其它国家的净出口。而这相当于抵消了世界其它国家政府购买商品和服务。利用政府购买的1.5的系数，可以得出中国出口顺差降低了世界其它国家GDP约为0.9x1.5=1.4个百分点左右。这样一来，中国虽然不是世界经济复苏的主要障碍，但也非常显著。根据美国占世界GDP的比例，以及1个百分点的GDP相当于1百万工作机会，得出结论：由于中国的重商主义，美国损失了140万就业机会。

看来贸易保护主义在2010年将要愈演愈烈。

Macroeconomic effects of Chinese mercantilism

For something I’m working on: we know that China is pursuing a mercantilist policy: keeping the renminbi weak through a combination of capital controls and intervention, leading to trade surpluses and capital exports in a country that might well be a natural capital importer. We also know, or should know, that this amounts to a beggar-thy-neighbor policy — or, more accurately, a beggar-everyone but yourself policy — when the world’s major economies are in a liquidity trap.

But how big is the impact? Here’s a quick back-of-the-envelope assessment.

Start with the Chinese surplus. It has been temporarily depressed by the world trade collapse, but seems to be on the rise again. Blanchard and Milesi-Ferretti, at the IMF but speaking for themselves, project a Chinese current account surplus for 2010-2014 of 0.9 percent of gross world product.

You can think of this as a negative shock to rest-of-world net exports. (Technically, that’s not quite correct — because the shock depresses res-of-world GDP and hence rest-of-world imports from China, the realized trade surplus is smaller than the shock. But that’s a small correction.)

In turn, this negative shock is like a negative shock to government purchases of goods and services. So it should have a similar multiplier. Multiplier estimates are all over the place, but tend to cluster around 1.5. So we’re looking at a negative impact on gross world product of around 1.4 percent. Not huge — China isn’t the principal obstacle to recovery — but significant.

And, if we think of the United States as bearing a proportionate share, and also use the rule of thumb that one point of GDP =1 million jobs, we’re looking at 1.4 million U.S. jobs lost due to Chinese mercantilism.