Why is it said that the Arctic Circle does not have fixed latitude?

The Arctic Circle is the invisible circle of latitude on the Earth’s surface at 66°33’ north. It is a geographic ring crowning the globe, and is approximately 2,655 kilometers from the North Pole. However, scientists say the Arctic Circle keeps shifting. 

You know that the Earth rotates on its axis like a spinning top - but it is a spinning top that has a little bit of wobble. 3ecause of this, the Earth’s axis shifts from about 22 to 24.5 degrees every 20,000 years. The 2.5 degrees of axis shift every 41,000 years equals about 320 kilometers of movement in that time, or about 25 feet each year. As a result, the exact location of the Arctic Circle keeps on changing!