Think coal, oil, and gas.
We get them from underground and we have been using them EXCESSIVELY since the industrial revolution.
We burn fossil fuels to produce electricity, heat our homes, run our cars, and even use them to make plastics. But why are they such a problem?
Firstly, burning fossil fuels is the number 1 cause of climate change. This is because when you burn them, they release carbon dioxide, which stays in the atmosphere and traps heat. This excess heat is causing droughts, floods, wildfires, and the mass extinction of species to name a few...
Secondly, fossil fuels are not renewable - they're finite - so once we use them, we lose them.
In summary, we need to stop burning fossil fuels.