Then the fourth angel poured out his bowl on the sun, and power was given to him to scorch men with fire. And men were scorched with great heat, and they blasphemed the name of God who has the power over these plagues; and they did not repent and give Him glory.
This judgment is really self-explanatory. God literally turns up the heat.
Dictionary.com gives several definitions to the term “scorch.”
1. To burn a surface of so as to change its color and texture.
2. To dry or shrivel with or as if with intense heat : parch b : to afflict pain, devastate; to destroy, as property of possible use to an advancing enemy before abandoning.
3. To cause intense heat or mental anguish (scorching sun) (scorching fury.)
Imagine that all the known resources of drinking water have been polluted rendering them unfit for human consumption. Next, the Lord sends a great heat so severe that it scorches everyone that is exposed to its rays. Some believe that the heat will be so intense that it will cause the great ice caps of Antarctica and surrounding areas to melt resulting in major flooding worldwide. I would assume that the lack of suitable drinking water compounded by great heat would accelerate the death toll.
You get the picture right, coupled with the lack of drinkable water, many still suffering with the loathsome boils, it would be difficult to properly explain the anguish people will suffer through with this judgment, many will die.
Next. The Fifth Bowl Judgment.