Upwelling-favorable winds have increased in several coastal upwelling systems, and may further increase in the future. The present study investigates the effects of upwelling intensification on ocean acidification in the California and Canary Current Systems (CSs). Model simulations show that the volume of water undersaturated with respect to aragonite almost triples in the California CS under a doubling of wind stress. In contrast, the same wind perturbation results in the disappearance of undersaturation in the Canary CS. These contrasting responses arise from the differences in the relative contributions of circulation and biological processes to aragonite undersaturation in the two systems and the sensitivity of these processes to upwelling intensification. When combined with rising atmospheric CO 2 and increased stratification, upwelling intensification accentuates acidification in the California CS and dampens it in the Canary CS. These findings highlight the challenge to predict the future evolution of ocean acidification in regions subject to concurrent disturbances.

Lachkar Z., in press. Effects of upwelling increase on ocean acidification in the California and Canary Current Systems. Geophysical Research Letters.Article (subscription required).