What human activities contribute to the greenhouse effect?
The burning of coal, oil and natural gas, as well as deforestation and various agricultural and industrial practices, are altering the composition of the atmosphere and contributing to climate change. These human activities have led to increased atmospheric concentrations of a number of greenhouse gases, including carbon dioxide, methane, nitrous oxide, chlorofluorocarbons and ozone in the lower part of the atmosphere. The relative importance of these gases is shown on the United Nations Environment Programme web site.
