Climate Change Impacts on the Patagonian Shelf Break Front.

We characterize long‐term trends of sea surface temperature (SST), absolute dynamic topography, and chlorophyll‐a (CHL) in the Patagonian shelf break front (SBF) using 27 years (1993–2019) of satellite data. Warming of the Argentinean shelf waters and the southwestward displacement of the Brazil‐Malvinas Confluence (BMC) impact the northernmost extension of the SBF. Cooling of the Malvinas Current (MC) and the concurrent warming of the adjacent shelf waters lead to a significant increase of SST gradients along the outer shelf. The southwestward displacement of the BMC implies a similar shift of the SBF. An increase in CHL trend appears to be associated with southerly wind anomalies along the shelf break. We estimate a southward shift of the northernmost penetration of the MC of −0.11 ± 0.076°/decade. Plain Language Summary: Climate change is drastically affecting global fisheries, impacting marine resources, economic revenues and the livelihood of local communities. This manuscript describes the impact of climate change on one of the largest chlorophyll‐a hotspots of the world ocean: The frontal system of the Patagonian shelf break, which is located in the southwestern portion of the South Atlantic Ocean. The urgency to study this highly productive but scarcely sampled region is predicated upon the necessity to bring it to the attention of scientific and political stakeholders, who are largely unaware of the climate related changes of the regional oceanic conditions and their impact on the marine ecosystems. We report that as a consequence of climate change there has been a warming of the Argentine shelf waters, a southwestward displacement of the Shelf Break Front, a change of speed of major currents, and a positive trend of chlorophyll‐a concentration associated with southerly wind anomalies along the shelf break. The rate of southward shift of the Shelf Break Front is −0.11 ± 0.076° decade. Key Points: Warming of continental shelf waters strengthens the cross‐shelf break temperature gradientsObservations indicate a long‐term southward and westward displacements of the Brazil Current and Brazil‐Malvinas ConfluenceWe present a new methodology to determine the northernmost latitude of the Malvinas Current [ABSTRACT FROM AUTHOR]