An emerging hazard to nesting sea turtles in the face of sea-level rise

Climate change poses a significant threat to sea turtles. In particular, beach erosion due to sea-level rise endangers sea turtle nests and can hinder the inland movement of nesting females. This study highlights an overlooked indirect hazard in the context of sea-level rise, namely the risk of nesting turtles to lethal falls from rocky cliffs exposed by beach erosion. We provide evidence of mortality of nine nesting green turtles ( Chelonia mydas ) found upside-down on the base of cliff ledges in Breem Island (locally known as جزيرة بريم), located along the northern Saudi Arabian Red Sea coast. One additional turtle was found flipped over but still alive. Our observations suggest that in areas where there is a continuum from the beach to the rocky cliffs (contrary to very steep cliffs bordering beaches), these structures pose a substantial hazard to nesting sea turtles when they attempt to return to the sea. Moreover, mean daily air temperatures of 31 ˚C (max. 44 ˚C) in the northern Red Sea likely exacerbate heat exhaustion of turtles that fall off the cliffs, providing a very narrow window for the animals to be rescued. This study underscores the need to integrate these indirect effects of sea-level rise into sea turtle vulnerability assessments, as well as the importance of implementing timely mitigation measures. Such steps are essential to meet the goals of the Kunming-Montreal Global Biodiversity Framework and support the survival of breeding sea turtles amidst climate change challenges.