The population would decrease because the food chain has been disrupted at the bottom
Water is less dense as a solid than as a liquid. Normally this is reversed. Water has its maximum density at 4 degrees Celcius.
The fact that ice is less dense than water allows it to float on top of ponds so fish, frogs, etc can survive winters.
Trees do not emit greenhouse gases. Rather, they are the natural resource that helps clean it out. However, due to deforestation, there aren't enough to combat the amount of gas that is produced at the current rate.
The heat causes them to open up and flow air
