Virtual water flows under projected climate, land use and population change: the case of UK feed barley and meat.

The flow of water through food commodity trade has been rationalized in the virtual water concept. Estimates of future virtual water flows under climate, land use, and population changes could have instrumental value for policy and strategic trade decisions. This paper estimated the virtual water flows associated with feed barley and meat imports to the UK under projected climate, land use, and population changes from the 2030s to the 2050s. The results show that future virtual water inflows associated with barley imports to balance domestic deficits are larger than total volume of water used in domestic barley production in the UK. Mean virtual water associated with total UK barley production ranged from 206 to 350 million m. This is much less than the mean total virtual water associated with barley imports (if total barley produced in the UK is used for feed), which ranged from 2.5 to 5.6 billion m in the 2030s to the 2050s for all land use and climate change scenarios. If domestic barley production is distributed to the different end uses, the total virtual water inflows associated with imports to balance domestic feed barley supply could be as high as 7.4 billion m. Larger virtual water inflows (as high as 9.9 billion m) were associated with feed barley equivalent meat imports. While the UK barley production would be entirely green, imports of either barley or meat would result in large blue water inflows to the UK. Virtual water inflows increased across the time slices for all emissions scenarios, indicating weak effectiveness of yield or productivity gains to moderate virtual water inflows. While increase in yield and land allocated to barley production should be adaptive targets, the UK needs to take policy and strategic actions to diversify trade partners and shift imports away from countries where blue water flows can exacerbate existing or potential water stresses.