(a) Nighttime Gnet (mmol C−1 m−2 h−1) against aragonite saturation state (Ωarag) in each of the tide pools. Regression lines are significant at the p < 0.05 level. (b) Coupled Model Intercomparison Project Phase 5 (CMIP5) global Ωarag anomalies relative to 1990–2000 mean values for the Representative Concentration Pathways 2.6 (RCP 2.6; blue) and 8.5 (RCP 8.5; red). Ωarag anomalies are multimodel ensemble mean values calculated from 8 CMIP5 models with fully coupled ocean biogeochemistry schemes. RCP 2.6 and RCP 8.5 respectively represent the most extreme mitigation and business-as-usual RCP scenarios conducted in CMIP5.