Climate change constitutes a selective pressure on populations because increasing temperatures result in a selective advantage or disadvantage for certain individuals depending on their genetic predisposition.We wrote a program to simulate such developments using the example of the reproductive success of cold-blooded animals. Cold-blooded animals were the obvious choice because their dependence on temperature can easily be described using mathematical formulas. We developed a computational model in which various environmental conditions can be changed. We were thus able to simulate how genetic predispositions of populations adapt under changed temperature conditions.