I put together a compact guide because Tagalog has so many useful ways to say 'scarcity' depending on tone and context.
For everyday conversation I reach for kakulangan or kakulangan ng (something) — kakulangan is straightforward: it means lack or shortage. You’ll hear kakapusan in slightly more formal or economic discussions; kakapusan feels closer to the English 'scarcity' used in policy, news, or school discussions about supply and demand. Kulang is the casual adjective: if food is scarce you might simply say ang pagkain ay kulang or konti ang pagkain. Kawalan literally means absence, so it’s good when you mean something is missing altogether rather than just in short supply.
There are related verbs and nouns that help paint nuance: pagkaubos or pagkaubos ng suplay refers to depletion or running out, pag-ubos stresses that something has been used up. Pagkukulang emphasizes the state or act of lacking (pagkukulang ng pondo). Kakaunti and konti are adjectives/adverbs that signal small quantity. I like to mix these depending on register — in a text to a friend I’ll write konti lang, but in a short essay I’ll use kakapusan or kakulangan — and that little choice changes how urgent or formal the scarcity sounds.