Climate change is likely to affect milk production because of the sensitivity of dairy cows to
14 excessive temperature and humidity. We use downscaled climate data and county-level dairy
15 industry data to estimate milk production losses for Holstein dairy cows in the conterminous
16 United States. On a national level, we estimate present-day production losses of 1.9% relative to
17 baseline production, and project that climate impacts could increase these losses to 6.3% by the
18 end of the 21st century. Using present-day prices, this corresponds to annual losses of $670
19 M/year today, rising to $2.2 B/year by the end of the century. We also find that there is
20 significant geographic variation in production losses and that regions currently experiencing the
21 greatest heat-related impacts are also projected to experience the greatest additional losses with
22 climate change. Specifically, statewide average estimates of end-of-century losses range from
23 0.4% in Washington to a 25% loss in annual milk production in Florida. Given that the majority
24 of these losses occur in the summer months, this has potential to significantly impact operations
25 in hotter climates.