Response of the California Current Ecosystem to Mitigation of Carbon Dioxide

Eastern Boundary Upwelling Systems (EBUS) are highly productive and biodiverse oceanic regions that provide food and economic security to many. These coastal regions face multiple threats, including ocean acidification, unsustainable fishing, and marine pollution. Using a small suite of GFDL models, Rykaczewski and Dunne (2010) project an increase, and poleward-shift in California Current Ecosystem (CCE) productivity under long-term warming, due to increased water-column stratification and decreased ventilation in the North Pacific leading to enriched source waters entering the CCE at depth. Efforts to sustainably manage and conserve these nutrient-rich EBU ecosystems need to incorporate knowledge and understanding of how EBUS could respond to a mitigation of carbon dioxide. The utility of idealized greenhouse gas reversibility scenarios to investigate processes driving responses under mitigation was demonstrated in a study by John et al. (2015), which showed enhanced productivity in many ocean areas even as mitigation is implemented. Here we will use an idealized 1% yr^-1 to 4xCO2 ramp-up/ramp-down scenario to investigate the response of the CCE to a mitigation of carbon dioxide, by assessing changes in key marine stressors (sea surface temperature, sea surface pH, oxygen, and primary productivity) at the end of the ramp-up and ramp-down.