Alright. Fluff your pillows and get comfortable, because you'll probably fall asleep before you finish reading this. This is probably not what any of you were looking for, since it's super abstract, so it's fine if you skip it all. tl;dr: it's both or neither, in the end.
I'll just state here: I won't be addressing the environmental questions or any question regarding "natural evils" (the world dying, the sun exploding, aliens coming to eat us, etc.) since I already have a really long answer for a simpler question below.
Let's start from the ground up, answering the most simple and basic element of this question: you are unhappy with the world. What can you do? I won't answer it with a philosophy paper, but I will answer it with a proof sketch: I'll be stating what I want to prove, and then provide arguments for it; together, if valid, they'll come to a valid conclusion.
The structure of the proof: #1 is our initial assumption; #2-8 will be proven; #9 is the logical conclusion if all previous points are true.
You are unhappy with the world.
If a human is unhappy with the world, it's because there exists some deficiency in the act of reason—whether in the self, in another, or in both. Here, we will exclude natural evils (natural disasters, animal attacks, etc.) as the question's presumably regarding the "human world" or "human civilization."
A deficiency in the act of reason consists in perceiving a disordered end to be good and willing it.
Such deficiencies can be intentional or unintentional.
Unintentional deficiencies can be corrected by proper education.
Intentional deficiencies can only be corrected by the agent himself.
Thus, to act to correct deficiencies, there are only three acts in the power of a single agent: 1) to correct deficiencies within oneself; 2) to correct unintentional deficiencies in another through education; 3) to encourage another agent to correct their intentional deficiencies.
However, it is a deficiency of the act of reason to fail to correct known deficiencies within yourself or an unintentional deficiency in another.
Therefore, the course of action according to reason is to correct both deficiencies in yourself and others. In other words, you cannot improve yourself without improving the part of yourself that isn't improving others; the opposite is true as well. One can either fully seek to improve both, or you can improve neither. This is due to the nature of reasoning well and acting well.
I suppose this is the time I begin some proof sketches for my seven claims. Man, this will take a while...
-#1 is our initial assumption; no proof is needed.
-#2: If a human is unhappy with the world, it's because there exists some deficiency in the act of reason—whether in the self, in another, or in both.
The proof for this really has its basis in a much older proof that you can look up: Aristotle's proof of how the function of a human being is to reason well. This ties into his understanding of virtue, morality, purpose, and so on. It's a very useful and interesting read, if you're ever interested! (and is the foundation for a very large amount of modern thought—perhaps even a lot of what you believe)
His function is (roughly) as follows: imagine a carpenter. When is the carpenter most perfectly a carpenter? When he does carpentry well. This is intuitive: a thing is most perfect when it performs its function perfectly. A warhorse is most perfectly a warhorse when it fulfills the function of a warhorse well: carrying its rider into battle; avoiding enemies; surviving; wearing armor well; etc. A shipbuilder is most perfectly a shipbuilder when he builds ships well. And so on.
What is the function of a human being? Well, what does a human being do? What defines a human being from everything else? We are animals; we live and breathe and eat and sleep like all animals do.
The difference is our intellect. We reason. We are rational animals, unlike all other animals. Only we have art, technology, philosophy, deep interpersonal communication, ritual, etc.; and all of that has, at its root, our reason. Our rationality.
That is the precise function of a human being: the function that separates us, makes us special, and defines us.
It makes sense, then, that we are most human when we are reasoning well. This also includes the aspect of an animal; of course; we have to breathe and eat and sleep; but those things too are related to reason. After all, our will lies within our reason: we can choose to eat or not eat; learn or not learn; think or not think; reason well or reason poorly.
We have the ability to function well by reasoning well, but we can choose not to. In fact, every choice is also a rational act.
Think about a choice you make. You choose to eat an apple. There's actually a lot of small steps you took there, but to simplify: you had the idea of eating the apple. You perceived this idea as a good: the act of eating the apple is seen as good because the end sought is perceived as good—the taste of the apple, presumably; though there are other ends one might seek as well, like nutrition, health, social responsibility if you're expected to eat it, etc.
Now, back to the original point: you are unhappy with the world. (I've taken "the world" to mean "the human world," or "all of humanity; human society and civilization," what have you.) Therefore, you perceive some element of the world as lacking an essential good; just as evil is a lack of essential good, so is unhappiness caused by a perceived lack of essential good.
Now, there are three cases. First is that your perception is false, and there is no lack of essential good in the world. In that case, the deficiency of reason is in your own reason. Second is the case where there really is a lack of essential good in the human world. Third is the case where both the first and second cases are true.
If there is a lack of essential good in the human world, we have to ask what the essential good for the human world is. Since we're talking about human civilization/society, the essential good for civilization is simply the good of all individual humans and the good of their union in societies or governments. The essential good for a human is gained by functioning well, which is to reason well; thus, any lack of essential good implies a lack of functioning well, which is a lack of reasoning well.
Therefore, if a human is unhappy with the world, there must exist some deficiency in human reason—whether it be their own, another's, or both—and the correction of this deficiency would result in the correction of the essential evil.
Now, I can prove #3 pretty easy, since we've already built up the framework: as stated earlier, human acts are acts of reason regarding things we perceive as good and thus choose to seek. Thus, a deficiency in reason is a deficiency in the perception of the good of the chosen end.
Let's put all of this into a practical example.
There is Cain and Abel, the only two humans upon the Earth. (I'll be veering from the original story a bit with this example.)
Cain sees Abel's fruits of labor, gets jealous, and asks Abel for some of the fruit. Abel says no. Cain becomes unhappy with the world.
His unhappiness stems from his perception of an evil: that he should have the same goods (the fruits) as Abel does.
There are three cases: 1) he is wrong: that is not actually an evil, and Cain's reasoning was faulty on that point; 2) he is correct: he should have the same goods as Abel, and Abel's reasoning was faulty on that point when he denied that statement; or 3) both were wrong, though that doesn't make sense in this case, since the perceived evils are in direct opposition.
There are other points to be asked: correcting that perception wouldn't solve the problem of not having the same good as Abel—if, for example, there weren't enough fruits to go around. But that's a "natural evil," as stated earlier; here, we're only discussing "human evils," so to speak; evils of human acts—and that will always have a root in a deficiency of human reason, whether intentional or unintentional, known or unknown.
I'm not going to prove the rest, because I'm fairly certain that if anyone has a problem with these sketches of proofs, they'll have long since arisen. If they don't, the rest is much more trivial to show and almost already follows from what we've discussed.