Final answer:
The burning of fossil fuels releases carbon dioxide (CO₂), which contains the element carbon and contributes to the greenhouse effect and global warming.
Step-by-step explanation:
The gases produced by burning fossil fuels typically contain the element carbon, due to the presence of carbon dioxide (CO₂). When fossil fuels such as coal, natural gas, and petroleum are combusted, the chemical reactions rearrange the carbon atoms within these fuels, combining them with oxygen to produce carbon dioxide.
This process is well-defined in chemistry (e.g., the reaction of methane in natural gas producing CO₂ and H₂O). The release of carbon dioxide, a known greenhouse gas, into the atmosphere is a significant contributor to the greenhouse effect and the ongoing issue of global warming.