Shoaling of the aragonite saturation horizon (ASH) poses a significant threat to calcifying organisms in deep water, particularly cold-water corals who use aragonite to make their skeletons. (c) Projected ASH depth for year 2020. (d) Projected ASH depth for year 2040. (g) Projected ASH depth for year 2099. Figure adapted and reproduced with permission, courtesy of John M. Guinotte, Marine Conservation Biology Institute, Bellevue, WA.