Explain why and how theories may be changed or replaced over time.

The answer would be new theories come up and are replaced by the older inaccurate theories. Obviously this theories are checked by scientists over and over and over again to see if they can make it more accurate and better.

The old theories can be changed proved wrong new technology can prove them wrong and new theories that are more scientifically possible or are easier to be scientifically proven come in and replace the old ones.

Your answer is: increased air temperatures  hope this ! : )

Postsecondary education i believe