Rensselaer Polytechnic Institute, Troy, NY, USA.
Centro de Estudios Demográficos, Urbanos y Ambientales, El Colegio de México, Ciudad de México, Mexico.
Water Res. 2019 Jul 1;158:157-158. doi: 10.1016/j.watres.2019.04.039. Epub 2019 Apr 20.
The virtual water hypothesis offers the reasonable proposition that if water-abundant regions export water-intensive products to water-scarce regions, the latter could devote their scarce resources instead to uses yielding higher economic returns. Zhao et al. show that trade flows in China do not adhere to this hypothesis, use the economic theory of comparative advantage to explore why, and seek a solution where both the hypothesis and the theory are apparently satisfied. However, they have not fully utilized the power of the theory: this is made evident by the fact that their calculations quantify what they call "the comparative advantage of land, labor and water," as stated in the title of the article. This Comment describes the significance of comparative advantage for this inquiry and our comparable investigation for the regions of Mexico. It concludes with the case for a collaborative effort to situate such single-country studies in the context of a model of global comparative advantages.
虚拟水假说提出了一个合理的命题，即如果水资源丰富的地区向水资源短缺的地区出口耗水密集型产品，后者可以将其稀缺资源转而用于产生更高经济回报的用途。赵等人表明，中国的贸易流动不符合这一假设，他们利用比较优势的经济理论来探讨原因，并寻求一种满足假设和理论的解决方案。然而，他们并没有充分利用该理论的力量：这一点从他们的计算结果明显看出，他们将标题中提到的“土地、劳动力和水的比较优势”量化了。本评论描述了比较优势对这一探究以及我们对墨西哥地区的类似调查的重要性。最后，提出了一个合作的案例，即将此类单一国家的研究置于全球比较优势模型的背景下。
