(The 3 examples are:)
~ CO2 from burning fossil fuels
~ gas (methane) leaks from underground gas pipes
~ methane from rotting material in landfills
(Other ones)
~ combustion of fossil fuels (oil, coal, and gas)
~ deforestation (decreasing amount of plants that remove CO2 from the atmosphere)
~ industrial production that uses petroleum based products (mineral/metal production)
