Matthew 24:22 And except those days should be shortened, there should no flesh be saved: but for the elect's sake those days shall be shortened.
Many people die:
During the tribulation a total of one half of the world’s population will die due to plagues and war (Rev 6:8; 9:18). There will be wars and famines and severe plagues and supernatural happenings on earth as God’s wrath is poured out. The tribulation is a time of God’s wrath being poured out upon the inhabiters of earth (Rev 6:15-17; 11:18; 14:19; 15:1; 16:1). God cleanses the earth of all the vileness that man has placed here in their rebellion against the Creator. In mercy God shortens the days so that some will survive.
Shortened time:
All through prophetic passages it speaks of three and one half years and seven years; it also mentions that the days will be shortened so that some will survive. In Daniel he mentions that the world ruler will make a covenant with “many” for one week which is interpreted as seven years. The tribulation period will last seven years and if the time is shortened, then it will not be seven years. If it is one day short it will not be seven years and there is a problem with what Scripture says. However, Jesus said that “days” will be shortened. During the tribulation there will be multiple seals, trumpet and vial judgments poured out upon the earth and they will affect everything from health, environment, animals, etc. the whole climate will be affected and the earth will go through tremendous upheavals.
In Rev 8:12 there appears another problem that causes some to wonder. This trumpet judgment sounds and the day and night are smitten so that the day does not shine for 1/3 and the night also does not occur for 1/3 of night time. If the day is cut short by 1/3 then it becomes night, and if the night is cut by 1/3 it becomes day. Both are smitten so that eight hours of the day is eliminated.
Potential answer to both problems:
A possible answer to both the days being shortened and the day/night being eliminated by 1/3 each can be answered by comparing Old and New Testament passages. In Rev 8:8 I says an object the size of a mountain that is on fire hits the sea killing 1/3 of the creatures that are in it, 1/3 of ships were destroyed and the sea turned to blood. Jesus mentioned stars falling from heaven in Matt 24:29. In Isa 24:20 it speaks of the earth reeling to and fro like a drunkard. Could it be that the earth will be hit so hard by a meteorite that it will increase the speed of earth so that a day will be only 16 hours instead of 24? This would make the year still having the proper amount of days and yet still fit into the prophecy of the days being shortened.
God and man involved in judgment:
During the terrible days of the tribulation God will be directly involved in pouring our His wrath upon earth. Some are specifically from God and others from men and some seem to be the combination of the two. God allows war on earth and perhaps even nuclear war while orchestrating other judgments in connection with men’s wickedness.