Roughly one quarter of global nitrogen emissions come from the production of goods and commodities that are consumed outside their country of origin, reports a paper published online this week in Nature Geoscience. The study quantifies the amount of nitrogen pollution generated for 188 countries and suggests that net importers of these goods and commodities (importing more than they export) are almost exclusively in the developed world, whereas the countries where the related production-and therefore pollution-occurs are often developing economies.
Reactive nitrogen gases produced from combustion and agriculture can contribute to air pollution, climate change and acid rain, and nitrate from fertilizers can pollute groundwater or create dead zones in lakes and coastal regions.
Manfred Lenzen and colleagues used an economic model and estimates of reactive nitrogen emissions from the production, transportation and consumption of commodities to quantify the amount of nitrogen emissions caused by a country’s consumption-for 188 countries, across nearly 15,000 economic sectors. They show that consumption in Brazil, China, India and the United States is responsible for nearly half (47%) of the world’s commodity-related nitrogen emissions (approximately 89 million tonnes). Finally, the authors find that consumption of foreign-produced goods is so great in some countries that they cause more nitrogen pollution in other nations than they do in their own.
In an accompanying News & Views article, James Galloway and Allison Leach write that Lenzen and colleagues reveal “the degree to which we may be, in effect, exporting our nitrogen pollution to other countries”.