The export of major food crops like wheat, maize and soybeans from many of the world's water-scarce area-the Middle East, North Africa, parts of South Asia, North China Plains, southwest USA, Australia-to relatively water-abundant parts of the world carries a high virtual water content   . Both importing and exporting countries are exposed to transboundary risk transmission through climate change impacts on distant water resources . Climate change is projected to exacerbate risk and add new vulnerabilities for risk transmission . Rising atmospheric CO2 concentration is projected to decrease water efficiency of growing maize and temperate cereal crops in parts of the USA, East and Mediterranean Europe, South Africa, Argentina, Australia and Southeast Asia, with important implications for future trade in food grains . By 2050 , virtual water importing countries in Africa and the Middle East may be exposed to imported water stress as they rely on imports of food grains from countries which have unsustainable water use . Until 2100, virtual trade in irrigation water is projected to almost triple  and the direction of virtual water flows is projected to reverse, with the currently exporting regions like South Asia becoming importers of virtual water . An additional 10-120% trade flow from water-abundant regions to water-scarce regions will be needed to sustain environmental flow requirements on a global scale by the end of the century . Exports of agricultural commodities contribute to deforestation, over-exploitation of natural resources and pollution, affecting the natural capital base and ecosystem services .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report