In 2014, a study found that most newly hatched loggerhead turtles were female, but there were still enough males to ensure the future of the population for a long time to come. If the temperature drops a few degrees below that mark, all the sea turtles are born male.
Unlike humans and most mammals, a green sea turtle's sex is determined by outside temperatures while they're still growing inside the egg.
The paper cautioned that environmental change could undermine the green ocean turtle's future.
The Green Turtle populations in the northern Great Barrier Reef are turning female - due to increased water temperatures.
A shift of just a few degrees can have big impacts on sex outcomes in sea turtles.
The study analyzed more than 400 turtles and was conducted by researchers from the U.S. National Oceanic and Atmospheric Administration, as well as the Queensland Department of Environment and Heritage Protection in Australia. With rising temperatures, no more males would be around to mate with females, which could ultimately crash the whole population of sea turtles. Using a combination of endocrinology and genetic tests, researchers identified the turtles' sex and nesting origin. Turtles were more than 99% female.
Specifically, 99.1% of juveniles, 99.8% of subadults, and 86.8% of adults in the population were female.
While in the warmer northern tip of the Reef, female green turtles accounted for a staggering 87 to 99.8 per cent of the population. In contrast, the southern region, where it is fairly colder, females accounted for only 65-69% of the population. Also, not only the higher temperatures affect the sex of the turtles but also increase mortality rates in turtle offspring.
Green sea turtles are considered endangered throughout much of the world, under siege from coastal debris, loss of habitat, fishing nets, and pollution, according to the International Union for Conservation of Nature. Sea turtle gender is dependent on the incubation temperature while a turtle is an embryo, a characteristic common in some reptiles.
"Realizing what the sex proportions in the grown-up reproducing populace are today, and what they may look like five, 10 and quite a while from now when these youthful turtles grow up and move toward becoming grown-ups, will be extraordinarily profitable".
"Australia must adopt ambitious climate change targets that will save the Reef and its unique creatures".