Are the plagues literal or figurative? It is difficult to know. Images in the book of Revelation normally call for a figurative reading. Most of the book, particularly the seals and trumpets, makes sense only in a symbolic way.
Figuratively, the plagues could represent the consequences that come as a result of sin. The Old Testament calls them the curses of the covenant. The boils of the first plague resemble leprosy, a symbol of the putrefying effects of sin on the soul. The waters turning to blood could conceivably be taken literally. But it would take the total abandonment of law and order or a universal war to cause so much bloodshed that the ocean waters turn a bloody red. If you take the image symbolically, it may represent that those whose hearts are set on sin lose access to the water of life. The scorching sun could represent the intensified glare of God's Word as it points out sin and calls for judgment on those who oppose Him.
But in the end, the plagues may simply be a fairly literal outline of the terrible experience of the wicked in the last generation. They will suffer sores and diseases, extreme pollution, and weather now completely out of control. Everything designed to make life worth living gets taken away.
People today don't want to talk about God's judgment. They feel that judgment is not what a deity is for. But Santa Claus theology cannot cope with the reality of evil or seemingly senseless suffering. To make God kind but never firm is to deny His Lordship over a world full of suffering. Facing hardship without some sense that God has a purpose in it leads only to a fatalistic resignation. A God who never inflicts corporate judgments on the world is not the God of Scripture--He is an idol of our own making.
It is not to say that anytime someone suffers it is a divine judgment of some sort. Some may experience suffering as a judgment, while others may encounter the same suffering as a test of faith. Suffering rarely reveals its purpose to us, but it always summons our attention to the God who can help us understand the purpose in our suffering. With all the wrongs that happen in this world, we should not find it hard to believe that our world needs God's judgments to bring about justice.
Lord, I thank You for the firmness of character that will right all wrongs in this world someday. Give me the confidence to trust Your Lordship of this world until then.