Jing Sun, Harold Mooney, Wenbin Wu, Huajun Tang, Yuxin Tong, Zhenci Xu, Baorong Huang, Yeqing Cheng, Xinjun Yang, Dan Wei, Fusuo Zhang, and Jianguo Liu

PNAS May 22, 2018. 115 (21) 5415-5419;

Significance

Achieving global environmental sustainability and food security is among the world’s biggest challenges. International food trade plays an important role in global food security. It is widely believed that importing countries benefit environmentally from international food trade at the environmental cost of exporting countries. Contrary to the conventional wisdom, our study reveals a major environmental problem in importing countries. The unexpected findings suggest the need to reevaluate environmental consequences of international trade in all importing countries through discussions regarding environmental responsibilities among consumers and producers. There is an urgent need for innovative solutions for reducing environmental pollution and enhancing food security to offset the negative impacts of international trade globally.

Abstract

Protecting the environment and enhancing food security are among the world’s Sustainable Development Goals and greatest challenges. International food trade is an important mechanism to enhance food security worldwide. Nonetheless, it is widely concluded that in international food trade importing countries gain environmental benefits, while exporting countries suffer environmental problems by using land and other resources to produce food for exports. Our study shows that international food trade can also lead to environmental pollution in importing countries. At the global level, our metaanalysis indicates that there was increased nitrogen (N) pollution after much farmland for domestically cultivated N-fixing soybeans in importing countries was converted to grow high N-demanding crops (wheat, corn, rice, and vegetables). The findings were further verified by an intensive study at the regional level in China, the largest soybean-importing country, where the conversion of soybean lands to corn fields and rice paddies has also led to N pollution. Our study provides a sharp contrast to the conventional wisdom that only exports contribute substantially to environmental woes. Our results suggest the need to evaluate environmental consequences of international trade of all other major goods and products in all importing countries, which have significant implications for fundamental rethinking in global policy-making and debates on environmental responsibilities among consumers, producers, and traders across the world.

See: http://www.pnas.org/content/115/21/5415

Figure 2: Per hectare N balance (A) and N application (B) for soybeans, corn, and rice cultivation before and after soybean decline, and percent contribution of Heilongjiang provincial N balance increase from the change of cultivated area and change of per hectare N balance (C). The Left bar in C is the percent contribution from the change of cultivated area (49% in sum, of which 3% from soybeans, 20% from corn, and 26% from rice); the Right bar is the percent contribution from the change of per hectare N balance (51% in sum, of which 8% from soybeans, 27% from corn, and 16% from rice).