Multidecadal loss of surface thermal structure in the largest marine upwelling ecosystems

• DOI: 10.31223/x5rj0r
• Publication Date: 2025-04-20T15:18:41Z
• Authors: Mario Pardo; Emilio Beier
• Keywords: Marine ecosystem

Step horizontal gradients of sea surface temperature (SST) occur around upwelling cores, eddies, meanders, current boundaries, island-effect mixing areas, among many other oceanographic features. These thermally structured areas provide ideal turbulence for phytoplankton growth and biomass aggregation, triggering complex abundant food webs, in turn exploited by populations marine megafauna fisheries. How the distribution degree this heterogeneity has varied at climate-change scales is unknown. In study, we prove that thermal structure ocean declined steadily most important ecosystems during last 41 years (1982-2022: -0.1°C SST standard deviation within 0.25x0.25-dregree cells seasonal peak). Years with low showed remaining hotspots towards close to shore. The mechanisms long-term decline remain unclear. correlation mean itself was negative but non-consistent regions, while increasing absolute dynamic topography strong all regions. This points a multidecadal heat content gain along water column as potential cause homogenization process. Arguably, loss could be related described declines redistributions some species.