Although forests are cut down for many reasons, the main factors have to do with money and people trying to put or keep a roof over their head. above their heads. As the forest loses more and more trees, it causes a significant loss to the environment. According to National Geographic, about 30 percent of the planet is covered in forests, but at the rate that trees are being cut down, National Geographic researchers estimate that the planet's tropical rainforests would disappear within just a century. In relation to human health, greenhouse gases are supposed to be absorbed by trees, but if they are not absorbed there can be an increase in CO2 in the atmosphere (which is normally supposed to be absorbed by trees and waters), and could increase health problems for all humans and others