Despite large-scale environmental changes in the Southern Ocean, such as the deepening of the summer mixed layer  , and the expected impacts via altered nutrient entrainment, light availability and grazer encounter rates  , assessments indicated no consistent changes in primary production at the circumpolar scale, as sectors and regions show different trends . Although a global assessment found no overall changes in circumpolar primary production from 1998 to 2015  , another study showed an overall increase in phytoplankton biomass in the mixed layer over the period 1997-2019 . Primary productivity has increased in the Pacific sector and decreased in the Atlantic sector and the Ross Sea  . Higher productivity has also been observed in regions where rapid environmental changes occurred, such as in the vicinity of retreating IS and declining sea ice cover off the Antarctic Peninsula  , although diversity of phytoplankton may decrease with warming temperatures and less sea ice  . In the future Southern Ocean, stronger upwelling due to strengthened westerly winds is projected to increase primary productivity at the circumpolar scale in the Antarctic Zone and to the north of the sub-Antarctic Front, but not in the sub-Antarctic Zone   . The largest changes are projected to occur after 2100 at 2-6℃ warming of the surface ocean . Such an increase in Southern Ocean productivity will lead to a decline in global ocean productivity , due to nutrient trapping  and altered ocean carbon uptake through ecosystem feedbacks .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report