Question

Many experts believe that if we continue to use fossil fuels at the rate we are now, we will run out of this natural resource by the middle to end of the twenty-first century. Fossils fuels, the remains of once living plants and animals, primarily recycle the element __________ and when burned, these fuels add the element back into our atmosphere.

Answer 1

Fossils fuels, the remains of once living plants and animals, primarily recycle the element carbon and when burned, these fuels add the element back into our atmosphere.

The element is carbon, but what is released into our atmosphere is CO2 (carbon dioxide). Carbon dioxide traps heat and that is why global warming exists, also.

Answer 2

The answer is Carbon Dioxide...or CO2. Carbon Dioxide is also considered pollution, and due to the greenhouse effect, it's trapped on our planet...
(hope it helped ^_^)