Regional Carrying Capacities of Freshwater Consumption-Current Pressure and Its Sources.

Sustainable freshwater management is an essential target for sustainability. The concept of planetary boundaries evaluates whether the environmental loads from humans are within the carrying capacity of the environment at a global level, while the region-specific assessment of carrying capacities of freshwater consumption can complement the global-scale sustainability assessment by shedding light on regional sustainability. We show that 24% of the total freshwater consumption exceeds the regional carrying capacities based on spatially and temporally explicit analysis (monthly data for around 11 000 watersheds). Although 19% of the current total freshwater consumption is determined as "luxury consumption" beyond basic needs, approximately 60% of the exceedance is attributed to basic needs of freshwater for sustaining human life. International trade alleviates the overall pressure on carrying capacity by approximately 4.8% (18.9 billion m3) at a global level through virtual water trade; however, several producer countries demonstrate additional overconsumption beyond the regional carrying capacities, while importer countries that can do so mitigate overconsumption. Appropriate irrigation water management and the location of crop production are the keys to maintain our freshwater consumption levels within the regional carrying capacities on a global scale. However, measures that necessitate the consideration of watershed-specific environmental and economic conditions are desirable.