My first theory is climate change. Climate change is the long-term change in average weather conditions including temperature, precipitation, and wind. People have many different opinions. Meaning that one person can like hot weather, while another person likes cold weather. So if a person did not like the weather conditions they could’ve left and went somewhere else.
My second theory is environmental damage. Environmental damage is how people damage the environment. So for example they cut down trees or loiter. Cutting down trees gets rid of homes for animals and such. Loitering is when people leave their garbage all over the earth, which makes the world gross.
Both of these theories have something to do
with people’s opinions. For example people might not like a certain climate, so they will leave. Some people don’t care if the world is full of garbage, so they will stay, while others will leave. They are both bad and can harm our world.