Longer life spans mean more people, worsening food and housing supply difficulties.
I reccomend changing the Sentence to;
Longer life spans can mean more people, thus worsening food and housing supply difficulties.
Personally your Sentence;
Longer life spans mean more people, as it worsens food and housing supply difficulties
Doesnt make much sense, your saying a Fact in the beggining, but then relating it to another fact in a rough manner, perhaps try making the second sentence more Comparing in a Cause to Affect form of sentence, which will make it seem more explaining to something else's effects. Yes I know the sentence goes like this:
Cause & effect, effect
but you want to make it seem more like
Cause & effect, and effect
(if that makes any sense)