Perhaps it will never come to that point in the first place.
Consider Revelation 21:10-16 (NKJV), where it reads:
"And he carried me away in the Spirit to a great and high mountain, and showed me the great city, the holy Jerusalem, descending out of heaven from God, having the glory of God. Her light was like a most precious stone, like a jasper stone, clear as crystal. Also she had a great and high wall with twelve gates, and twelve angels at the gates, and names written on them, which are the names of the twelve tribes of the children of Israel: three gates on the east, three gates on the north, three gates on the south, and three gates on the west.Since 12,000 furlongs is roughly equivalent to 1,400-1,500 miles, this passage speaks of a gigantic cube or maybe even a pyramid. I began to wonder...where on Earth would you put such a massive structure? Putting the center of it on the site of modern day Jerusalem would mean that part of it would stretch out over the Mediterranean Sea, while the other end would be somewhere in far eastern Iraq. To the north it would cover parts of Turkey, and to the south it would go into the Sudan. Architecturally, that seemed a little unrealistic given the current topography of the land in that region of the world.
Now the wall of the city had twelve foundations, and on them were the names of the twelve apostles of the Lamb. And he who talked with me had a gold reed to measure the city, its gates, and its wall. The city is laid out as a square; its length is as great as its breadth. And he measured the city with the reed: twelve thousand furlongs. Its length, breadth, and height are equal."
I then recalled another passage in II Peter 3:10 (NKJV) which states:
"But the day of the Lord will come as a thief in the night, in which the heavens will pass away with a great noise, and the elements will melt with fervent heat; both the earth and the works that are in it will be burned up."Now if this event occurs before the New Jerusalem is lowered from the clouds, does that mean many of the seas and oceans would have been boiled off? If so, that would make it easier to drop a giant cube onto the landscape, because it would solve the water problem. It may or may not take care of the canyons left behind when seas evaporated, however. Then again, a 1,400 mile cube coming down from above would probably crush anything in its path.
Going back to the sea level issue, though, even if the levels fluctuate a bit, they will never wipe out everything, as God told Noah in Genesis 9:11 (NKJV):
"Thus I establish My covenant with you: Never again shall all flesh be cut off by the waters of the flood; never again shall there be a flood to destroy the earth.”Will the ice caps melt enough to wipe out whole nations and destroy some (but not all) coastal cities? In Job 38:8-11 (NKJV) God tells Job:
“Or who shut in the sea with doors, When it burst forth and issued from the womb; When I made the clouds its garment, And thick darkness its swaddling band; When I fixed My limit for it, And set bars and doors; When I said, ‘This far you may come, but no farther, And here your proud waves must stop!’"Maybe the issue of the entire planet being burnt up is a little more significant. This time, however, it won't have anything to do with carbon emissions.