'Increasing ocean acidification and oxygen loss are negatively impacting two of the four major upwelling systems: the California Current and Humboldt Current . Ocean acidification and decrease in oxygen level in the California Current upwelling system have altered ecosystem structure, with direct negative impacts on biomass production and species composition .' 'Three out of the four major Eastern Boundary Upwelling Systems  have shown large-scale wind intensification in the past 60 years . However, the interaction of coastal warming and local winds may have affected upwelling strength, with the direction of changes  between and within EBUS . Increasing trends in ocean acidification in the California Current EBUS and deoxygenation in California Current and Humboldt Current EBUS are observed in the last few decades , although there is low confidence to distinguish anthropogenic forcing from internal climate variability. The expanding California EBUS OMZ  has altered ecosystem structure and fisheries catches .' 'Overall, EBUS have been changing with intensification of winds that drives the upwelling, leading to changes in water temperature and other ocean biogeochemistry .' 'The direction and magnitude of observed changes vary among and within EBUS, with uncertainties regarding the driving mechanisms behind this variability. Moreover, the high natural variability of EBUS and their insufficient representation by global ESMs  gives low confidence that these observed changes can be attributed to anthropogenic causes.'
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report