The answer lies in finding a fuel that will not produce carbon dioxide and pollutants.

Right now, humans are producing carbon dioxide faster than the environment can absorb it.

Converted to oil and burned, the same refuse produces carbon dioxide instead.

But cars tend to be much more fuel-efficient and therefore produce less carbon dioxide.

To produce less carbon dioxide, cars would have to be more fuel efficient.

Another reason is that as a candle burns it produces carbon dioxide.

So if we produce too much carbon dioxide, the planet should warm up.

Trees produce carbon dioxide at night, when they are not photosynthesizing.

Every stage in the nuclear process, except fission, produces carbon dioxide.

It can be produced in many different ways, but many of the methods produce carbon dioxide.