Tropical vs. temperate sea turtle population resilience to extreme temperatures

[Display omitted] •Nest incubation temperatures were higher for green turtles than for loggerhead turtles.•The nests in Cape Verde had higher temperatures than the ones in Greece.•Exceeding the nest temperature of 31 °C and 32 °C resulted in a reduction in hatching success.•Future warming incubation temperature of nests might pose a threat to sea turtles. Rising temperatures due to global warming over the last decades pose threats to marine biodiversity. Sea turtles are ectothermic species, and their embryonic development depends on nest conditions, particularly temperature. Here, we explore how increasing and extreme temperatures within the 558 nests can impact the hatching success of two sea turtle species, the green turtle (Chelonia mydas) and the loggerhead turtle (Caretta caretta), at two tropical locations, Cape Verde and Australia, and at temperate nesting sites, Turkey and Greece. Mean nest temperatures were higher for green turtles (30.84 °C) than for loggerhead turtles (29.42 °C) and significantly increased in all locations as the air temperature increased. However, nests from temperate locations, such as green turtles in Turkey and loggerhead turtles in Cape Verde, experienced higher temperatures than the nests in Australia and Greece, reaching lethal temperatures at extreme temperature peaks. Thus, temperate populations might be at risk as global warming continues because it is uncertain whether these higher latitudes can provide beach habitats cool enough for successful sea turtle nesting given the projected more frequent extreme temperatures in the future.