Like many reptiles the ratio of males to females depends on the temperature.
Many more creatures depend on a relatively stable temperature range to remain viable. All are part of a food chain. If a link is knocked out, the predator can starve, and the prey overpopulate. Evolution is a relatively slow process. If change happens too quickly, the creatures don't have time to adapt, and the link is knocked out. This can lead to the collapse of the food chain.