Leatherbacks nest in the tropics but range widely in the world’s oceans, moving into colder, higher latitude waters during summer months. Climate change is expected to significantly disrupt the marine and terrestrial environments on which they depend.
Threats related to Global Warming
Climate change is altering the oceans physically and chemically as warmer waters expand, ice covers recede, circulation patterns change, and the pH of the oceans declines. Leatherbacks (and all six other species of marine turtles) will be affected by freshwater from melting glaciers, changes in salinity and oxygen, and altered ocean chemistry as shifts occur in currents, key habitats, and the range and abundance of prey species.
Changing ocean conditions are especially threatening in the Pacific where leatherback nesting populations are declining dramatically. Warmer-than-usual waters of El Nino years significantly reduce oceanic productivity by inhibiting the mixing of surface water with deeper, cold waters, resulting in less available food near the surface and reducing the reproductive potential of leatherbacks and other marine species.
Global climate change threatens reproduction on nesting beaches throughout the leatherback’s range. The sex of a developing leatherback embryo is dependent on the temperature of incubation in the nest, with warmer temperatures producing females and cooler temperatures producing males. Warmer beaches initially will produce more female offspring, to the detriment of the production of males; hot beaches ultimately will be lethal to embryos. Seasonal variation in rainfall and drought will alter incubation conditions and increase embryo losses. Other effects of climate change include increased numbers of hurricanes and severe storms, associated beach erosion, nest loss and the destruction of nesting habitat.
Changing marine temperatures are expected to continue to alter the range of leatherbacks. In the last 17 years, leatherbacks have expanded their range in the North Atlantic by about 250 miles.