The increased loss of the ecosystems including wetlands, wildlife, rainforests, coral reefs, aquatic life forms, and grasslands are highly influenced by overpopulation. It is out of overpopulation that activities such as excessive agriculture, environmental pollution, and extensive land development have become more and more intensive.

For example, rainforests originally covered 14% of the entire earth’s surface. Today, rainforests only cover about 6% of the earth’s surface and scientists forecast it may even become less in the next four decades judged by the current rate of vegetation removal, logging, and deforestation. Besides, due to environmental pollution, 30% of the ocean reefs have been lost because of acidification and global warming since 1980. Also, more than half of the original wetlands have been lost.

Humans store energy in (26) bodies, the earth stores the sun’s energy. The sun’s energy is stored in coal, natural gas, water and wind. Coal, oil, and natural gas are called fossil fuels. We use the energy in these fossil fuels to (27) electricity. We use electricity in many different ways. We light and heat our homes, schools and businesses using electricity, and to run computers, refrigerators, washing machines, and air conditioners. Our cars and planes run (28) gasoline, which comes from oil. By the year 2013, most of the energy we use comes from fossil fuels. (29) , fossil fuels are non-renewable sources of energy. They cannot be used over and over again. This means that one day they will run out! Luckily, there are some renewable energy sources we can use. Unlike non-renewable fossil fuels, they will not run out. Three forms of renewable fuels are solar (coming from the sun) energy, water energy and wind energy. All these renewable energy sources are (30) for us because they will not run out, so we need to get better and better at using them.