The Rate of Coastal Temperature Rise Adjacent to a Warming Western Boundary Current is Nonuniform with Latitude.

Western boundary currents (WBCs) have intensified and become more eddying in recent decades due to the spin‐up of the ocean gyres, resulting in warmer open ocean temperatures. However, relatively little is known of how WBC intensification will affect temperatures in adjacent continental shelf waters where societal impact is greatest. We use the well‐observed East Australian Current (EAC) to investigate WBC warming impacts on shelf waters and show that temperature increases are nonuniform in shelf waters along the latitudinal extent of the EAC. Shelf waters poleward of 32°S are warming more than twice as fast as those equatorward of 32°S. We show that nonuniform shelf temperature trends are driven by an increase in lateral heat advection poleward of the WBC separation, along Australia's most populous coastline. The large‐scale nature of the process indicates that this is applicable to WBCs broadly, with far‐reaching biological implications. Plain Language Summary: As the circulation in ocean basins intensifies, it causes changes in the currents on their western boundaries which carries heat toward the poles. While we know that this causes warming in the open ocean, knowledge of how these changes affect coastal and shelf regions is limited. Here, we use a suite of different observations and an ocean model to show that, off the coast of southeastern Australia, the coastal ocean is warming two or three times faster in areas poleward of where the East Australian Current separates from the coast than where the East Australia Current remains close to the coast. This is due to the shelf waters poleward of where the current separates from the coast receiving an increase in the amount of warm water being pushed onto them as the southern outflow of the East Australia Current becomes more turbulent and eddying. This warming is driven by large‐scale changes in wind patterns, and so is likely to be common to other similar current systems. As coastal ecosystems are the most productive, we expect this nonuniform warming to have a widespread biological impact. Key Points: Temperature trends on a western boundary shelf are 2× greater poleward of the separation point than equatorward of the separation pointEquatorward of the separation point, mean kinetic energy increases, while poleward (downstream) eddy kinetic energy increasesThis latitudinal difference in warming is driven by increased eddy driven heat advection onto the shelf downstream of the separation point [ABSTRACT FROM AUTHOR]