How Climate Change Could Make Sea Turtles Extinct
Sea turtles already have it bad. Egg thieves. Mile-wide fishing nets. Sea walls. Now climate change may just push them over the edge.
Across the globe, sea turtle population numbers have plummeted from historical accounts of abundance. For example, leatherback populations in the Eastern Pacific have dropped by 95 percent over the last generation.
And while bycatch in industrial fishing gear, coastal development and their direct harvest have played a role in their decline, climate change may be the final nail in the coffin for these gentle ocean creatures.
The impacts of climate change are already well-documented: an increase in ocean temperatures, a more acidic ocean, melting ice caps and rising sea levels.
It’s the last one that might be the worst for sea turtles.
That’s because sea turtles nest and lay eggs on beaches around the world and many of these beaches are at risk of being submerged by rising sea levels, eroding shorelines and storm surges.
You might wonder whether the pregnant sea turtles can just find other nesting beaches on which to lay their eggs.
Turtles imprint at birth on the beach where they are born, and scientists are not sure yet whether they can adapt in time. But looking at climate prediction data, we can already see that some current beaches might be completely lost or nesting habitat reduced to a dangerously small amount.
For example, look at the case of the Hawaiian green sea turtle, locally called the honu. Today 90 percent of the Hawaiian greens nest on French Frigate Shoals, part of an atoll located in the Northwestern Hawaiian Islands. Since the elevation of the nesting beach on these islands is six feet above sea level, the predicted sea level rise over the next hundred years might completely inundate the honu’s main nesting site.
And the Hawaiian green is not the only species at risk. Climate mapping prediction software has identified that Padre Island, Texas, the major U.S. nesting site for the endangered Kemp’s ridley sea turtle, might also be completely lost.
Other nesting beaches will erode due to climate change. In an ideal world, sea turtles might be able to follow these beaches as they retreat inland (if it not backed by a cliff). But poor coastal development policies, such as in Florida, will mean sea turtles will encounter sea walls and buildings, and have nowhere to nest.
Our strategy to protect sea turtles from rising seas must be comprehensive: prevent and reverse poor coastal development policies; make sure coastal resiliency projects are turtle friendly; in the worst cases, establish secondary nesting colonies to prevent catastrophic extinction; reduce other threats to sea turtles such as their drowning in fishing gear and illegal harvesting of eggs so baseline population numbers are not so fragile.
And, of course, we need to reduce our climate change emissions to bring carbon dioxide levels below 350 part per million and reduce ocean acification. If we can reverse climate change, we might just give endangered sea turtles a fighting chance.