Human interference: When we cut down forests, make more factories, and drive more cars that burn fossil fuels, the way that carbon and nitrogen move around the Earth changes. These changes add more greenhouse gases in our atmosphere and this causes climate change. The burning of large quantities of fossil fuels, especially from coal, releases larger amounts of hydrogen sulfide gas into the atmosphere. As rain falls through this gas, it creates the phenomenon known as acid rain. Humans have also altered the phosphorus cycle in aquatic systems, directly, by mining phosphorus-rich rock, and indirectly, through the manipulation of other element cycles and the alteration of aquatic food webs.
