in the future, there will be very much people, about 7 billion in 2020.
Then will be more factories and cars polluting the atmosphere and increasing the "Greenhouse Effect", with a global rise in temperature.
It would affect to the planet geography with natural disasters: storms, floods, hurricanes, earthquake... also it would increase the arid zones on earth.the harmful gases absorb the sun's

heat and make the earth hotter. credits: see the links