Potential impact of global warming on North Pacific spring blooms projected by an eddy-permitting 3-D ocean ecosystem model

Abstract

Using an eddy-permitting ecosystem model with a projected physical environment from a high-resolution climate model, we explored the potential impact of global warming on spring blooms in the western North Pacific. We focused on statistically significant signals compared with natural variability. Considering 2xCO2 conditions, maximum biomass during the spring bloom is found to occur 10 to 20 days earlier due to strengthened stratification, and in the subarctic region, the bloom to decrease in magnitude relative to pre-industrial simulation. However, in the northern part of the Kuroshio extension region where photosynthesis is not strongly limited by nutrients, the maximum biomass increases by 20 to 40%associated with rising temperatures, even though the annually averaged biomass slightly decreases. Our results reveal that even if global warming weakly affects annually averaged quantities, it could strongly affect certain species and biogeochemical processes which depend on seasonal events such as blooms. Copyright 2009 by the American Geophysical Union.