Environmental literacy can be defined as: "the degree to which people have an objective and well-informed understanding of environmental issues." Today, it is extremely important to have a understanding of environmental issues. This is because the human economy is engaged in a wide range of activities that are causing enormous damage to the ecosystems that sustain both our species and Earth's legacy of biodiversity. All around us, this is witnessed by pollution, climate warming, collapsing fisheries, deforestation, the degradation of agricultural soil, extinctions and endangerment of species, and other damages. Environmental pollution is one of the most serious problems facing humanity and other life forms on our planet today. "Environmental pollution is defined as "the contamination of the physical and biological components of the earth/atmosphere system to such an extent that normal environmental processes are adversely affected." Pollutants can be naturally occurring substances or energies, but they are considered contaminants when in excess of natural levels.