Carl Gallups explains the world events that relate to the prophecies of the fourth and fifth trumpet. You can read the biblical text for the forth and fifth trumpet below (Revelation 8:12-).
Forth Tumpet: The Heavens Struck
Then the forth of the angels sounded: And a third of the sun was struck, a third of the moon, and a third of the stars, so that a third of them were darkened. A third of the day did not shine, and likewise the night.
And I looked, and I heard an angel flying through the midst of heaven, saying with a loud voice, “Woe, woe, woe to the inhabitants of the earth because of the remaining blasts of the trumpet of the three angels who are about to sound!”
Fifth Trumpet: The Locusts From the Bottomless Pit
Then the Fifth trupet sounded: And I saw a star fallen to the earth. To him was given the key to the bottomless pit. And he opened the bottomless pit, and smoke arose from the pit like the smoke of a great furnace. So the sun and the air were darkened because of the smoke of the pit.
Then out of the smoke locusts came upon the earth. And to them was given power, as the scorpions of the earth have power. They were commanded not to harm the grass of the earth, or any green thing, or any tree, but only those men who do not have the seal of God on their foreheads,
And they were not given authority to kill them, but to torment them for five months. Their torment was like the torment of a scorpion when it strikes a man. In those days men will seek daeth but will not find it; they will desire to die, but death will flee from them.
The shape of the locusts was like horses prepared for battle. On their heads were crowns of something like gold, and their faces were like faces of men. They had hair like women’s hair, and their teeth were like lions’ teeth. And they had breastplates like breatplates of iron, and the sound of their wings was like the sound of chariots with many horses running into battle.
They had tails like scorpions, and there were stings in their tails. Their power was to hurt men five months. And they had as king over them the angel of the bottomless pit, whose name in Hebrew is Abaddon, but in Greek he has the name Apollyon.
One woe is past. Behold, still two more woes are coming after these things.”