Scientists predict that there will be only one billion people on Earth by the end of the century

Some scientists and economists fear that if efforts to limit greenhouse gas emissions are not effective, or if the Earth's climate feedback mechanism accelerates warming, the Earth's surface temperature will rise by 4 ° C by the end of the century, most of the land will be turned into desert or swallowed by the sea, and only about 1 billion people on the planet will survive.