Analyses of satellite-derived primary production over the past two decades  showed generally weak and negative trends  at low and mid latitudes . In contrast, positive trends occurred in large areas of the South Atlantic and South Pacific Oceans, as well as in polar and coastal  regions . Data-assimilating ocean biogeochemical models estimate a global decline in primary production of 2.1% per decade in the period 1998-2015, driven by the shoaling mixed layer and decreasing nitrate concentrations . This is consistent with previous assessments that identified ocean warming and increased stratification as the main drivers  affecting the regional variability in primary production Bindoff et al. . However, as noted in SROCC and WGI AR6 Chapter 2 , observed interannual changes in primary production on global and regional scales are nonlinear and largely influenced by natural temporal variability, providing low confidence in the trends.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report