Paper Reviewed
Wyneken, J. and Lolavar, A. 2015. Loggerhead sea turtle environmental sex determination: Implications of moisture and temperature for climate change based predictions for species survival. Journal of Experimental Zoology (Molecular and Developmental Evolution) 324B: 295-314.

In light of fears that have been fostered by false predictions of CO2-induced global warming, Wyneken and Lolavar (2015) describe how certain climate alarmists have proposed that because marine turtles have their sex determined by incubation temperature, "elevated temperatures might skew sex ratios to unsustainable levels, leading to extinction," while adding that these people additionally claim that "elevated temperatures may also reduce availability of suitable nesting sites via sea level rise," and that "increased tropical storm activity can directly affect nest site moisture, embryonic development, and the probability that nests will survive." But are these concerns really valid?

In an attempt to find out, the two researchers "sampled primary sex ratios from a major Florida loggerhead rookery under typical and more extreme climatic conditions," discovering that "samples were 100% female when weather conditions were hotter and drier than normal," but that "eggs that incubated in hot but wet years produced mixed sex samples." And in clutches they reared in the laboratory under moist conditions at temperatures predicted to produce female-biased sex ratios, they say "they produced ~90% males."

"These findings," as Wyneken and Lolavar conclude, "indicate more conditional responses to climate change than previously considered, and cause us to question the generally accepted assumption that changes in temperature, alone, will have a negative impact on sex ratios." In fact, they say that "currently, science lacks the ability to predict the effects of climate change on sea turtles (and likely other species) with environmental sex determination because of small sample sizes, few longitudinal studies, little verification of embryonic stages, little verification of sex ratios in situ, and focus on individual factors e.g., temperature)."