Jesus' disciples asked Jesus when the "the conclusion of the system of things" would take place. (Mt. 24:3)
Jesus then spoke of future signs that would mark his presence and of a “great tribulation such as has not occurred since the world’s beginning until now, no, nor will occur again.” (Mt 24:21)
The apostle Paul referred to the execution of God’s judgment upon the ungodly as tribulation:
“This takes into account that it is righteous on God’s part to repay tribulation to those who make tribulation for you, but, to you who suffer tribulation, relief along with us at the revelation of the Lord Jesus from heaven with his powerful angels in a flaming fire, as he brings vengeance upon those who do not know God and those who do not obey the good news about our Lord Jesus.” (2 Thess. 1:6-8)
As to the extent of this tribulation, Jesus said that it will be on a scale “such as has not occurred since the world’s beginning until now, no, nor will occur again. In fact, unless those days were cut short, no flesh would be saved”. - Mt 24:21, 22
Because the global flood occurred "since the world's beginning", presumably the extent of the great tribulation would surpass even that.
2 Tim. 3:1 says that "in the last days critical times hard to deal with will be here." "Critical" means vital...life or death.
But the scriptures assure us that after the Great Tribulation and Armageddon, paradise on earth will be restored:
For more, see:
Should You Fear the Great Tribulation?
ARMAGEDDON - A Happy Beginning
THE LAST DAYS - WHEN?