The capacity of seaweeds to adapt and/or acclimate to climate change might differ among distinct populations, depending on their local environmental history and phenotypic plasticity. Kelp forests create some of the most productive habitats in the world, but globally, many populations have been negatively impacted by multiple anthropogenic stressors, including ocean warming (OW). However, it has also been shown that local drivers such as nitrogen (N) availability might modulates their responses to global stressors by enhancing their thermal tolerance. Here, we compare the physiological and molecular responses to ocean acidification (OA) and OW of two populations of the giant kelp Macrocystis pyrifera from distinct regimes of CO2 , pH, temperature and N availability (weak vs strong upwelling ). We found that juveniles Macrocystis sporophyte responses to OW and OA did not differ among populations: elevated temperature reduced growth while OA had no effect on growth and photosynthesis. However, we observed higher growth rates and NO3- assimilation, and enhanced expression of metabolic-genes involved in the NO3 - and CO2 assimilation in individuals exposed to strong coastal upwelling . Our results suggest that despite no inter-population differences in response to OA and OW, intrinsic differences among populations might be related to their local natural environmental variability driven by coastal upwelling. Financial support: FONDECYT 3170225, CeBiB FB 000-1 (ANID).