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