A particular brand of environmentalist is campaigning to leave natural gas in the ground under the pretense of fighting climate change. But alternatively, those molecules could one day replace steel and all the greenhouse emissions associated with making it.
Science is full of surprises, especially chemistry.
The main component of natural gas is methane, a potent greenhouse gas that is much more damaging to the environment than carbon dioxide. While burning natural gas to make electricity is cleaner than coal, methane leaks during drilling and shipping can negate the overall benefits, hence the controversy.