What happens when humans burn fossil fuels?
carbon is released into the atmosphere.
carbon is removed from the atmosphere.
temperatures on earth decrease.
carbon is destroyed.

Carbon is released into the atmosphere is the correct answer.

Explanation:

Fossil fuels are nonrenewable resources. When humans burn fossil fuels it affects the air quality, human health, environment, and level of carbon  increases which results in climate change.When fossil fuel: oil, natural gas, and coal are burned by the human activities it releases carbon in the atmosphere.When the fossil fuel is burned carbon combines with oxygen to form Carbon dioxide and it increases the concentration of greenhouse gases.Burning of fossil fuel increases the level of carbon dioxide gas, which heats the lower atmosphere, results in Greenhouse and global warming.

Thus when humans burn fossil fuels Carbon is released into the atmosphere.