Avoidable impacts of ocean warming on marine primary production: Insights from the CESM ensembles

Here we use two ensembles of the Community Earth System Model (CESM) run under the business-as-usual scenario, RCP 8.5, and the mitigation scenario, RCP 4.5, to identify avoidable impacts of anthropogenic warming on marine net primary production (NPP). We emphasize the use of ensembles so as to distinguish long-term, anthropogenic trends in marine productivity from internal variability.

Twentieth century globally integrated marine NPP is 55.7 1PgC, with much of the variability attributable to certain regions (e.g., the equatorial Pacific). CESM projections indicate that global marine NPP will drop by approximate to 4% by 2080 if we follow RCP 8.5, but only by 2% under RCP 4.5. The response to warming on a global scale includes compensating regional effects; NPP increases in polar and eastern equatorial Pacific waters but decreases in the Atlantic, western Pacific, and Indian Oceans.