Global Decoupling of Deep Ocean Nutrient Upwelling & Primary Productivity Collapse

The systemic decoupling of deep ocean nutrient upwelling from surface photic zones represents a major biogeochemical shift, projected to significantly reduce the rate and spatial extent of global primary productivity (PP) by 2060. This process is fundamentally driven by anthropogenic warming and atmospheric CO2 absorption, which accelerate oceanic stratification in major circulation systems, notably impacting the Atlantic Meridional Overturning Circulation (AMOC). Historically, deep-sea currents delivered critical limiting nutrients—primarily nitrates and phosphates—to the surface layers, fueling massive photosynthetic output that supports the global marine food web. The current thermal gradient increase creates a persistent density barrier, trapping these essential resources below the photic zone and diminishing their availability for phytoplankton blooms near the surface.