To test this hypothesis, we compared trends in nitracline and phosphacline depths in the CMIP6 Earth System Models across historical and future emission scenarios (i.e., less and more stratified scenarios, respectively) (Fig. ). In the historical scenario, all models predicted nutricline trends notably smaller than the observed trends. In some models, equivalent trends for the 5 nitracline and phosphacline depths at Redfield proportions (i.e., TPO4 = TNO3) were seen. For other models, the phosphacline showed a faster deepening trend compared to the nitracline, whereas the opposite was never seen. These findings generally held true under future emission scenarios, although most models predicted faster deepening of both nitracline and phosphacline depths in the future. In conclusion, greater stratification generally led to a faster nutricline deepening in CMIP6, 10 but some models included biogeochemical processes causing a faster deepening of the phosphacline relative to the nitracline.