An egg in hot sand is more likely to produce a female turtle, and an egg in cool sand is more likely to produce a male.
The sex of green turtles is influenced by temperatures during their incubation period and a difference of just a few degrees in the temperature of nests - which are dug into beaches - can result in a population that is 100% male or female.
The research, that was facilitated by the Rivers to Reef to Turtles project and led by WWF Australia, was published in the journal Current Biology.
Since figuring out the sex of buried eggs is too hard, researchers chose to catch sea turtles and use genetic tests to find out where they'd come from.
"While these turtles may be half a world away, action to reduce carbon emissions in the United Kingdom can play a vital role in limiting the impact of global warming on green turtles and countless other marine species", he said. Turtles from the cooler southern GBR nesting beaches showed a more moderate female sex bias (65 to 69 percent female). Scientists who are behind the research are from the National Oceanic and Atmospheric Administration (NOAA), California State University, and the Worldwide Fund for Nature Australia.
Thousands of Newborn Sea Turtles Scurry Down the Beach to the Pacific Ocean
Climate change is turning the green turtle population in parts of the Great Barrier Reef nearly entirely female, experts have discovered.
But those in the warmer, northern Great Barrier Reef were "extremely female-biased", at 99.1 percent female among juveniles and 99.8 percent for those between juveniles and adults. Among those born north of Cooktown, however, 99.1 percent of the juvenile turtles Jensen examined were female, along with 86.8 percent of adults.
So, the researchers developed a new technique: Studying the turtles' hormones.Proving that the increasing temperatures actually changed the turtle population proved challenging, though.
The study "provides a new understanding of what these populations are dealing with", he said.
"Knowing what the sex ratios in the adult breeding population are today and what they might look like five, 10 and 20 years from now when these young turtles grow up and become adults is going to be incredibly valuable". "We know that species evolve in response to climate and other environmental changes, but they need time for that". On the other hand, the scientists are taking important steps like trialing the use of shade cloth in nesting beaches which will lower the sand temperature, and trying to reduce bycatch in the fishing industry, stated O'Gorman.