We're still closer to Ice Age temperatures than global historical normal.

I think so.
if the temperatures are extremely high, more male than female turtles/crocodiles will be born.

you raised a good point about these ancient creatures being able to adapt since prehistoric times!

cryotosensei

It still doesn't make sense as a story. These organisms are super ancient. They've mostly existed in far warmer environments than this one.

If something's making them dangerously feminine, it's more likely to be something like agrochemical and pharmaceutical contaminants in the water.

Animal_World

Global warming and turtles/crocodiles

I suppose it would be a U-shaped curve.

It still doesn't make sense as a story. These organisms are super ancient. They've mostly existed in far warmer environments than this one. 

If something's making them dangerously feminine, it's more likely to be something like agrochemical and pharmaceutical contaminants in the water.