If something makes people miserable or causes them great pain and torment, it's a scourge. A corrupt government is one kind of scourge, and a plague of insects that destroys a farmer's crops is another kind of scourge.
Dating from the 13th century, scourge originally meant "a whip used as punishment." It wasn't long until the figurative meaning of "something causing pain or misery" became even more common. A scourge tends to be something that causes folks to suffer terribly, whether it's a tsunami or unjust laws. You can also use this word as a verb: "Cutting the city's transportation budget will do nothing but scourge people without cars."