text: Air pollution The industry is the largest industrial source of emissions of volatile organic compounds (VOCs), a group of chemicals that contribute to the formation of ground-level ozone (smog). The combustion of fossil fuels produces greenhouse gases and other air pollutants as by-products. Pollutants include nitrogen oxides, sulphur dioxide, volatile organic compounds and heavy metals.
  Researchers have discovered that the petrochemical industry can produce ground-level ozone pollution at higher amounts in winter than in summer.
  Climate change
  Greenhouse gases caused by burning fossil fuels drive climate change. In 1959, at a symposium organised by the American Petroleum Institute for the centennial of the American oil industry, the physicist Edward Teller warned of the danger of global climate change. Edward Teller explained that carbon dioxide "in the atmosphere causes a greenhouse effect" and that burning more fossil fuels could "melt the icecaps and submerge New York".
  The Intergovernmental Panel on Climate Change, founded by the United Nations in 1988, concludes that human-sourced greenhouse gases are responsible for most of the observed temperature increase since the middle of the twentieth century.
  As a result of climate change concerns, many people have begun using other methods of energy such as solar and wind. This recent shift has some petroleum enthusiasts skeptical about the future of the industry.