Earth Two

The debate over global warming stopped in the summer of 2073 when the last ice field at the South Pole vanished. By then the oceans of the world had risen between twenty-one and twenty-four feet, swamping every city and town located on the coastal plains of Earth. Twenty-one billion people were living on a planet that was running out of time. The pollution streaming from the factories of the world had poured into small streams, which in turn had drained into the larger streams and rivers that had dumped their toxic arsenal into the oceans.
From the beginning of time the oceans had fed the human race with such an abundant variety of sustenance that no one ever dreamed that one day there would be no more fish or other crustaceans to fill their bellies. Mankind had cut and burned the forests of Earth and cemented over the fertile ground to make way for buildings and factories that took more by the hour from the Earth than the Earth could replenish.
A third of the world's population now lived and worked underground. By 2180 the Earth was shrouded in a thick, black mist that let little sunlight penetrate to the cities below.
A young scientist, Carson Chase, has discovered a far distant world whose chemical signals are the same as Earth's, and the three richest and most powerful nations still left on Earth see the handwriting on the wall. They unite to manufacture the largest ship mankind has ever built in an attempt to voyage to this new Earth Two before time runs out on humanity.