1.  Air Pollution  Water Pollution  Deforestation  Desertification

2.  Air is 99.9% nitrogen, oxygen, water vapor and inert gases.  Human activities can release substances into the air, some of which can cause problems for humans, plants, and animals. There are several main types of pollution:  Smog  acid rain  the greenhouse effect  "holes" in the ozone layer.

6. When a pollutant, such as sulfuric acid combines with droplets of water in the air, the water (or snow) can become acidified.

9.  The Greenhouse Effect, also referred to as global warming, is believed to come from the build up of carbon dioxide gas in the atmosphere.

11.  Water pollution is the contamination of water bodies such as lakes, rivers, oceans, and groundwater caused by human activities.  It can be harmful to organisms and plants that live in these water bodies.

14.  The permanent destruction of native forests and woodlands.  This does not include logging industrial forests such as pines and palm forest plantations  Slash and Burn agriculture is the biggest agent

19.  Desertification is the process which turns productive into non- productive desert as a result of poor land-management.  Desertification occurs mainly in semi-arid areas bordering on deserts.