1. Theme 3:

2. WP10 Future changes in ocean carbonate chemistry Objectives: Determine future changes in carbonate chemistry (pH, CaCO 3 saturation states, etc.) and associated uncertainties using a range of coastal-, basin-, and global-scale models. Identify critical regions (hot spots) where changes and variability in carbonate chemistry are largest. Assess commitment of past and future carbon emissions (i.e., the anthropogenic perturbation’s inertia after emissions are halted) in terms of future changes of carbonate chemistry.

3. WP10: Description of work and roles of PI’s: T1: Simulations - Use a hierarchy of models (high-resolution regional to global models) to simulate future carbonate chemistry over the 21stcentury and beyond focusing on changes in the North Atlantic, Arctic, European shelf seas, and upwelling systems (All partners: UiB, AWI, LSCE, PML, MPG, UBERN, ETHZ, MEL-IAEA) T2: Model-data comparison - Rigorously evaluate models against existing data over the industrial period (link with WP2 and WP3) (All partners) T3: Model-model comparison - Provide uncertainties by comparing models results to one another in critical regions (see above) where model domains overlap (All partners) T4: Sensitivity studies - Perform sensitivity studies to determine how predicted ocean acidification changes (1) under a range of physical forcing and greenhouse gas scenarios in different models (All partners) and (2) with improved model resolution, i.e., a systematic comparison of coarse, eddy permitting, and eddy resolving versions of global and European shelf sea models (MEL-IAEA, LSCE, ETHZ, PML)

4. WP10: Deliverables D10.1: Preliminary report on the range of expected future changes in carbonate chemistry, intended to influence the design of EPOCA’s mesocosm studies (month 12; R, PU) D10.2: Report comparing anthropogenic changes in carbonate chemistry with natural variability (month 24; R, PU) D10.3: Archive of three-dimensional model fields of carbonate chemistry made available to the community (month 36; O, PP) D10.4: Report assessing how improved model resolution and forcing affects simulated 21stcentury pH and carbonate saturation states (month36; R, PU) D10.5: Report assessing hot spots, thresholds, and uncertainties in terms of simulated future pH and carbonate saturation states completed and provided to WP13 (month42; R, PU)

5. Theme 3:

6. WP12 Assessment and Earth system feedbacks Objectives: Quantify links and feedbacks between carbon emissions, ocean acidification, and climate in coupled, state-of-the- art Earth system models -Explore ocean acidification under a range of mitigation and non-mitigation scenarios -Determine how ocean acidification will simultaneously affect ocean productivity and climate reactive gases as well as the climate system

7. WP12: Description of work and roles of PI’s: T1: Perform simulations with five Earth system models from five centres of excellence in numerical modelling (UiB, LSCE, MPG, UB and UBERN), while simultaneously bringing together emerging process-based knowledge from other Themes T2: Perform sensitivity tests in Earth system models to isolate effects due to climate change as well as how increasing atmospheric CO2drives changes in ocean biogeochemistry and ecosystems that in turn feedback on climate T3: Quantify uncertainties by comparing results from models having different physics and biogeochemical-ecosystem components (UiB, LSCE, MPG, UB and UBERN) T4: Comparison of the new scenario results including new parameterisations for the acidification impact with previous results (UiB, LSCE, MPG, UBERN and MEL-IAEA)

8. WP12: Deliverables D12.1: Impact of future ocean acidification using results from existing Earth system models (month 12; R, PU) D12.2: Model output from the four Earth system models stored in a common format in a central archive (month 36; O, PP) D12.3: Potential future thresholds that may result from synergistic effects of simultaneous changes in ocean biogeochemical and ecosystem processes, report provided to WP13 (month 42; R, PU) D12.4: Evolution of ocean acidification and climate as well as uncertainties across a range of emission scenarios considered by IPCC WG-III for IPCC’s 4th Assessment Report (month 48; R, PU) D12.5: Final model output archive made available to the public after quality control (month 48; O, PU)