Global environmental costs of China's thirst for milk. (5),

: 29 China has an ever-increasing thirst for milk, with a predicted 3.2-fold increase in 30 demand by 2050 compared to the production level in 2010. What are the environmental 31 implications of meeting this demand, and what is the preferred pathway? We addressed 32 these questions by using a nexus approach, to examine the interdependencies of 33 increasing milk consumption in China by 2050 and its global impacts, under different 34 scenarios of domestic milk production and importation. Meeting China’s milk demand 35 in a business as usual scenario will increase global dairy-related (China and the leading 36 milk exporting regions) greenhouse gas (GHG) emissions by 35% (from 565 to 764 Tg 37 CO 2 ) and land use for dairy feed production by 32% (from 84 to 111 million ha) 38 compared to 2010, while reactive nitrogen losses from the dairy sector will increase by 39 48% (from 3.6 to 5.4 Tg nitrogen). Producing all additional milk in China with current 40 technology will greatly increase animal feed import; from 1.9 to 8.5 Tg for concentrates 41 and from 1.0 to 6.2 Tg for forage (alfalfa). In addition, it will increase domestic dairy 42 related GHG emissions by 2.2 times compared to 2010 levels. Importing the extra milk 43 will transfer the environmental burden from China to milk exporting countries; current dairy exporting countries may be unable to produce all additional milk due to physical 45 limitations or environmental preferences/legislation. For example, the farmland area 46 for cattle-feed production in New Zealand would have to increase by more than 57% 47 (0.1 million ha) and that in Europe by more than 39% (0.5 million ha), while GHG 48 emissions and nitrogen losses would increase roughly proportionally with the increase 49 of farmland in both regions. We propose that a more sustainable dairy future will rely 50 on high milk demanding regions (such as China) improving their domestic milk and 51 feed production efficiencies up to the level of leading milk producing countries. This 52 will decrease the global dairy related GHG emissions and land use by 12% (90 Tg CO 2 53 reduction) and 30% (34 million ha land reduction) compared to the business as usual 54 scenario, respectively. However, this still represents an increase in total GHG 55 emissions of 19% whereas land use will decrease by 8% when compared with 2010 56 levels. 57