Current virtual water trade cannot be sustained

Water is a precious resource and scarce in many countries. Countries can compensate for this scarcity by importing products which contain “virtual water”, for example, water-intensive goods like food. How will future water scarcity affect global consumption and the international water trade?

Vergrösserte Ansicht: Bottled water
(Foto: Steven Depolo / flickr)

Water is an essential resource for life and many economic sectors. Arid regions of the world are already suffering from periodic or permanent water scarcity. This situation is expected to become more critical in the future, when a changing climate shifts water resources across the globe and global population and water demand increase. While the resulting water scarcity directly limits the domestic consumption of water within a nations’ territory, it also affects the trade of so-called “virtual water” – water which is used for producing industrial and agricultural products. In a recent ETH study [1] we investigated the possible effects of future water scarcity on global consumption and the international water trade. This allowed us to identify countries where future water consumption is likely to be limited, either by a country’s own domestic water scarcity or because its trading partners are no longer able to sustain their virtual water exports.

Complex dependencies

Besides climate change and the resulting patterns of future water availability as projected by Global Climate Models [2], future water consumption depends on many factors such as population and economic development, dietary changes and technological advances. Projecting future water consumption requires modelling assumptions for all these factors, each of them subject to considerable uncertainties. We bypass these difficulties by simply investigating whether today’s patterns of virtual-water consumption and trade could work under the constraints of future water availability.

Reduced water availability would have a straightforward impact on domestic production – if future domestic water availability drops below the requirements of today’s production, today’s production cannot be sustained. Such reductions can result in declining exports or reduced domestic consumption or both. In our study we assume an egoistic behaviour of nations, meaning that a nation always prioritizes the consumption of its population over its exports.

Consumption affected for different reasons

Confirming earlier studies (e.g. [3], [4]), we find that countries of the Mediterranean, in the arid parts of North and Southern Africa, Central and Latin America, and Australia experience reduced future water availability and a corresponding need to adapt their water consumption. More surprisingly, countries from the wet north such as Russia and the Scandinavian nations also need to adapt their consumption. Their need does not come from domestic water scarcity, but rather from the fact that some of their trading partners experience water scarcity and thus cannot sustain their current exports.

Effects in a dry climate scenario

Vergrösserte Ansicht: Worldmap
Countries where more than half of the consumption of domestic and traded virtual water is unsustainable due to future water scarcity are shown in brown. Blue highlights countries with sustainable consumption. (Image: Orlowsky / ETH Zurich)

Almost all countries need to adapt their water consumption to varying degrees in order to respond to climate change. The map shows countries in brown which need to adapt at least half of their water consumption in a dry climate scenario. In the white areas, countries need to adapt less than half of their water consumption. Only for the very few blue countries – Costa Rica, the Netherlands, Belgium, Denmark and Luxembourg – consumption is fully sustainable.

It is important to keep in mind that we cannot understand one country’s individual need to adapt from a local perspective alone, simply comparing domestic water availability and need. Instead, the global virtual-water trade network connects supply and demand across nations. These connections provide for a more efficient use of water resources on a global level, but at the same time they allow water scarcity to propagate to countries which are themselves water-rich. In its present form, the current virtual-water trade network cannot be sustained in the expected future climate.

References

[1] Orlowsky, Boris, Arjen Y. Hoekstra, Lukas Gudmundsson and Sonia I. Seneviratne. 2014. “Todayʼs virtual water consumption and trade under future water scarcity.” Environmental Research Letters, 9, 074007. doi:10.1088/1748-9326/9/7/074007

[2] Warszawski, Lila, Katja Frieler, Veronika Huber, Franziska Piontek, Olivia Serdeczny, and Jacob Schewe. 2014. “The Inter-Sectoral Impact Model Intercomparison Project (ISI–MIP): Project Framework.” Proceedings of the National Academy of Sciences 111 (9): 3228–32. doi:10.1073/pnas.1312330110.

[3] Oki, Taikan, and Shinjiro Kanae. 2006. “Global Hydrological Cycles and World Water Resources.” Science 313 (5790): 1068–72. doi:10.1126/science.1128845.

[4] Portmann, Felix T, Petra Döll, Stephanie Eisner, and Martina Flörke. 2013. “Impact of Climate Change on Renewable Groundwater Resources: Assessing the Benefits of Avoided Greenhouse Gas Emissions Using Selected CMIP5 Climate Projections.” Environmental Research Letters 8 (2): 024023. doi:10.1088/1748-9326/8/2/024023.

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