Such gases are for instance carbon dioxide, methane, [nitrous oxide]?, [water vapor]? and [chlorinated fluorocarbons]? (CFCs) such as freon?.
Since the beginning of the Industrial Revolution, the concentrations of many of the greenhouse gases have increased. Carbon dioxide is up 30%, methane over 50%, [nitrous oxide]? 15%. As the concentrations of greenhouse gases in the atmosphere increases the temperature increases, leading to global warming.
Most scientists believe that the increased concentration of greenhouse gases is caused by human activity, primarily the burning of fossil fuels.
see also environmental agreements