The “earth ” represents the world of mankind alienated from God. Such a world existed in Noah’s day and, by divine decree, ended with the Flood.
أَمَّا « ٱلْأَرْضُ » فَتُمَثِّلُ عَالَمَ ٱلْجِنْسِ ٱلْبَشَرِيِّ ٱلْمُبْعَدِ عَنِ ٱللهِ .‏