Rising global temperatures are another consequence: newborn turtles are now almost all females. Scientists say that almost all of the newborn sea turtles hatched in Florida beaches in the past four years are females, which is due to rising temperatures. Moreover, the situation appears to be global, and a study of the population of green sea turtles on Australia's Great Barrier Reef found the same problem: In the warmer northern regions of the Great Barrier Reef, researchers found that 99.1 percent of young turtles, 99.8 percent of sub-adult sea turtles and 86.8 percent of adult green sea turtles were females, and only about 1 percent of green sea turtle young turtles were born male.
Unlike most species that determine sex during fertilization, most turtles are sex determined after fertilization. That is, the incubation temperature of the turtle eggs in the sand after fertilization determines whether the newborn turtle is male or female, in technical terms called "temperature-dependent sex determination mechanisms". Studies have shown that if turtle eggs hatch below 27.7° Celsius, the turtle larvae will be males. However, if turtle eggs hatch above 31° Degrees Celsius, the larvae will be females. Fluctuating temperatures between the two extremes will produce a mixture of male and female juvenile turtles. This critical incubation period is called the thermal phase, which is an irreversible sex determination period during the development of the relevant species. A severe imbalance in the male-female ratio of turtles will result in poor population development.
Not only turtles, but also the offspring of some crocodiles, lizards, and bony fish are influenced by temperature-dependent sex-determining mechanisms. The facts could not have been clearer, global warming is already a fait accompli and is causing serious repercussions for many species that cannot adapt.
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