Influence of the mightiest rivers worldwide on coastal sea surface temperature warming.

Ocean warming as a consequence of climate change occurred during the last decades is not homogeneous. This is especially patent for coastal areas, where the warming is influenced by local processes that occur at different time and spatial scales. In this sense, plumes formed by rivers discharge can play a key role in sea surface temperature (SST) warming. SST trends for the coastal points affected by the plumes of the 19 world's mightiest rivers (south 60°N) and their oceanic counterparts were analyzed by means of NOAA's AVHRR OISST data over the period 1982-2019. Coastal areas affected by river plumes showed an annual less intense warming trend than observed at the adjacent ocean in all cases. In average, warming trend was 0.088 °C dec lower for coastal areas, ranging from 0.027 °C dec for Mekong and Irrawaddy/Salween River plume systems to 0.208 °C dec and 0.278 °C dec for Mississippi and Paraná River plumes. The differences in coastal-ocean warming obtained for rivers debouching into inland seas (Danube and Volga Rivers) are similar to the ones observed for the rest of the rivers, even if inland seas are prone to higher warming rates than open seas. As the main conclusion, river plumes seem to have the ability to modulate SST warming near coast within the current context of global warming.