In the first sentence, the phrase what's called the greenhouse effect presents a/an

Greenhouse effect is a social problem where the gases from CFCs accumulated to the earth’s stratosphere causing pollution and trapped heat. Green house is one of the ways people could avoid greenhouse effect. In making your house green, that is making it plant-friendly, you will be breathing more oxygen, less carbon dioxide. Chlorofluorocarbons (CFCs) chemicals contain carbon, chlorine and fluorine and is t so expensive at the same time it’s not flammable, the reason why it is mainly used in business such as refrigerators and plastics. However, these chemicals destroys our stratosphere, the second layer of the Earth’s atmosphere and protects us by blocking the ultraviolet radiation (UV Light). This type of radiation can seep through organisms skins and can leave destructive effects on DNA molecules which will also cause skin cancer.