Industrialised societies use a great deal more energy per person than those in the developing world. The average person in the UK uses 35 times as much energy as someone in India. Much of this energy comes from non-renewable sources such as fossil fuels (coal, oil and gas). These fuels are being used at a much faster rate than they are produced, and may be unavailable to future generations. In addition, the environmental effects of energy production from fossil fuels can be harmful. These include the greenhouse gases which may cause global warming, and sulphur dioxide and nitrogen oxides, which leads to acid rain.