I don't know how brief I can make it, but just try to cut what I say lol.
The earth once had a low average temperature, like an ice cream. However, the greenhouse effect (sunlight being trapped by greenhouse gases, like CO₂) started causing global warming, which meant that the temperature increased. Natural climate change also meant that the average temperature increased. This meant that many of our ice caps (produced from our low average temperature) melted, and became water due to the increasing temperature. This is much like ice cream, as when the temperature gets too hot, it melts and just becomes a creamy liquid.
