But the planet is getting warmer—and that means many more turtles, in key nesting sites like Florida, are being born female. “Scientists studying sea turtle hatchlings and eggs have found no baby sea turtles, so only female sea turtles for the past four years,” Bette Zirkelbach, who runs a turtle rescue in the Florida Keys, told Reuters. Sea turtles live in the ocean, but they come to beaches around the world to lay their eggs in the sand. When the sand is cooler, more of those eggs become male—and when it’s warmer, more of the eggs become female. The exact temperature at which the change occurs can vary between species and locations, but at around 29 degrees Celsius (84 degrees Fahrenheit) you’ll often see a 50/50 split between male and female chicks. However, the climate crisis is raising temperatures around the world and the oceans are teeming with female turtles. In 2019, the Miami Herald reported that a scientist in South Florida had documented only female hatchlings in seven of the previous 10 years. These kinds of results appear elsewhere. A 2018 paper found that while cooler beaches on Australia’s Great Barrier Reef had between 65-69 percent female turtles, warmer beaches on the reef had more than 90 percent female turtles. In Cape Verde, an island nation off West Africa, light-sand beaches produced about 70 percent female turtles, while dark-sand beaches produced about 93 percent female turtles, according to a 2014 study. colors absorb more energy from the sun, making them warmer. This process is called “feminization” – and some scientists warn it could be a long-term threat to sea turtles as the climate crisis pushes temperatures even higher, as both males and females are needed for the species to reproduce. The same issue may also threaten other reptiles whose eggs are sexed based on temperature, such as alligators. There are some possible mitigations for this problem, such as providing more shade on beaches, covering nests in light sand, or moving nests to cooler areas. But all of this requires human intervention in the nesting process, which sea turtles have been doing undisturbed for millions of years. In addition to warmer temperatures, sea turtles face other climate-related threats, such as rising sea levels and intense hurricanes, which can damage their coastal nesting sites.
