Book about water seeping up from inside the earth over decades, eventually covering the earth completely. Published at least 10 years ago The book describes how water starts seeping to earth's surface from lakes inside earth. Scientists trying to find out where all the water comes from. Cities slowly beginning to be submerged over the years. The main characters grow older, many attempts are made at escaping from earth. Arks are built, subsequent generations start growing webbed feet and fins. The book describes how landmark after landmark disappears under
Flood by Stephen Baxter, published in 2008.
Undersea aquifers are breached and the Earth's oceans begin to rise. The book follows a number of different characters as land area shrinks and finally vanishes.
I think the webbed feet and fins are just discussed as speculation. The world begins work on three different Ark projects that are basically; boat, undersea habitat and spaceship.
Here's the GoodReads blurb...
Sea levels have begun to rise, at catastrophic speed. Within two years London and New York will be under water. The Pope will give his last address from the Vatican before Rome is swallowed by the rising water. Mecca too will vanish beneath the waves.
The world is drowning. A desperate race to find out what is happening begins. The popular theory is that we are paying the price for our profligacy and that climate change is about to redress Gaia’s balance. But there are dissenting views. And all the time the waters continue to rise and mankind begins the great retreat to higher ground. Millions will die, billions will become migrants. Wars will be fought over mountains.