Recent history and geography of virtual water trade - PubMed (original) (raw)

Recent history and geography of virtual water trade

Joel A Carr et al. PLoS One. 2013.

Abstract

The global trade of goods is associated with a virtual transfer of the water required for their production. The way changes in trade affect the virtual redistribution of freshwater resources has been recently documented through the analysis of the virtual water network. It is, however, unclear how these changes are contributed by different types of products and regions of the world. Here we show how the global patterns of virtual water transport are contributed by the trade of different commodity types, including plant, animal, luxury (e.g., coffee, tea, and alcohol), and other products. Major contributors to the virtual water network exhibit different trade patterns with regard to these commodity types. The net importers rely on the supply of virtual water from a small percentage of the global population. However, discrepancies exist among the different commodity networks. While the total virtual water flux through the network has increased between 1986 and 2010, the proportions associated with the four commodity groups have remained relatively stable. However, some of the major players have shown significant changes in the virtual water imports and exports associated with those commodity groups. For instance, China has switched from being a net exporter of virtual water associated with other products (non-edible plant and animal products typically used for manufacturing) to being the largest importer, accounting for 31% of the total water virtually transported with these products. Conversely, in the case of The United states of America, the commodity proportions have remained overall unchanged throughout the study period: the virtual water exports from The United States of America are dominated by plant products, whereas the imports are comprised mainly of animal and luxury products.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1

Figure 1. The virtual water import-export balance (m3) for the years 1986, 1993, 2000 and 2010.

The total flux along the network has more than doubled, and the number of nodes net importing has risen from 127 to 149 with a corresponding decrease in net exporters from 104 to 72. As such the ratio of net importers to exporters has changed from 1.2 to 2.0.

Figure 2

Figure 2. The virtual water import-export balance m3 per capita for the years 1986, 1993, 2000 and 2010.

Figure 3

Figure 3. The degree (the sum of import and export connections) associated with each country for the years 1986, 1993, 2000, and 2010.

While countries in general are more connected, this increase has not been as significant in most African countries.

Figure 4

Figure 4. The increase in virtual water trade and the percentage of the total virtual water flux in the network corresponding to plant, animals, luxury, and other commodities.

While there is an increase in the virtual water flux associated with all commodity categories, the fraction of the total flux associated with animals and other has decreased. There is a corresponding almost tripling of crop products and luxury products over the 25 year period with animal products and fibers increasing to a lesser extent.

Figure 5

Figure 5. Detailed virtual water trade (1011 m3) by commodity type for China (mainland), Germany, Italy and Japan.

Positive values refer to exports and negative values to imports. The insets indicate the percentage of virtual water imports or exports contributed by plant, animal, luxury and other products.

Figure 6

Figure 6. Detailed virtual water trade (1011 m3) by commodity type for Brazil, India, The United States of America and Australia.

Positive values refer to exports and negative values to imports. The insets indicate the percentage of virtual water imports or exports contributed by plant, animal, luxury and other products.

Figure 7

Figure 7. The Network associated with the top 50% of the virtual water flux for the years 1986, 1993, 2000 and 2010.

Color in the links based on the most prevalent commodity along the link in terms of total flux through the link. The heavy lines indicate the links which comprise the top 25% of the virtual water flux.

Figure 8

Figure 8. Detailed virtual water trade (1010 m3) by commodity type for Hungary, Poland, Bulgaria and combined former USSR and Russian federation.

The insets indicate the percentage of virtual water imports or exports contributed by plant, animal, luxury and other products.

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