Eutrophication: This is when a body of water becomes overly enriched with minerals and nutrients which induce excessive growth of algae. This process may result in oxygen depletion of the water body after the bacterial degradation of the algae.
Smog: A type of air pollution that's a mixture of smoke and fog caused by industrial pollutants and burning fuels which results in hazy air that can cause health issues.
Greenhouse gases: These are gases in Earth's atmosphere that trap heat. They let sunlight pass through the atmosphere but prevent the heat that sunlight brings from leaving the atmosphere causing global warming.