The four materials mentioned in the article are cement, steel, plastics, and ammonia.
Warren Buffet sometimes talks about looking for these kinds of need items, and then making sure they are well represented in your stock portfolio. He considers it better than hedge funds, since the risk (and potential reward) is greater, but the likelihood of the companies failing, even in hard times, are pretty slim.
> They All Require Fossil Fuels
It's a good headline in the sense that it summarises the article well. That's clearly the impression the author was going for.