Answer:
And He has made from one blood every nation of men to dwell on all the face of the earth, and has determined their preappointed times and the boundaries of their dwellings (ACTS 17:26).
The Bible tells us that the fountains of the great deep burst forth. This was unlike anything that we can even imagine! This breaking up of the earth caused the oceans to heat up and caused ash and dust to fill the air, blocking out sunlight, making the temperatures on earth cooler. As the warm water from the oceans evaporated into the air, forming clouds, the colder air over the earth caused wintry conditions, lots of snow, and ice glaciers. This could have very easily caused an Ice Age that lasted hundreds of years. When we start with what the Bible tells us, we can find the truth!
Source: https://answersingenesis.org/kids/anatomy/why-dont-we-all-have-the-same-color-of-skin/