Competing effects of wind and buoyancy forcing on ocean oxygen trends in recent decades.

Ocean deoxygenation is becoming a major stressor for marine ecosystems due to anthropogenic climate change. Two major pathways through which climate change affects ocean oxygen are changes in wind fields and changes in air-sea heat and freshwater fluxes. Here, we use a global ocean biogeochemistry model run under historical atmospheric forcing to show that wind stress is the dominant driver of year-to-year oxygen variability in most ocean regions.

Misconceptions of the marine biological carbon pump in a changing climate: Thinking outside the "export" box.

The marine biological carbon pump (BCP) stores carbon in the ocean interior, isolating it from exchange with the atmosphere and thereby coregulating atmospheric carbon dioxide (CO ). As the BCP commonly is equated with the flux of organic material to the ocean interior, termed "export flux," a change in export flux is perceived to directly impact atmospheric CO , and thus climate. Here, we recap how this perception contrasts with current understanding of the BCP, emphasizing the lack of a direct relationship between global export flux and atmospheric CO .

Effects of phytoplankton physiology on global ocean biogeochemistry and climate.

The similarity of the average ratios of nitrogen (N) and phosphorus (P) in marine dissolved inorganic and particulate organic matter, dN:P and pN:P, respectively, indicates tight links between those pools in the world ocean. Here, we analyze this linkage by varying phytoplankton N and P subsistence quotas in an optimality-based ecosystem model coupled to an Earth system model. The analysis of our ensemble of simulations discloses various feedbacks between changes in the N and P quotas, N fixation, and denitrification that weaken the often-hypothesized tight coupling between dN:P and pN:P.