By 2100, Earth’s rising population is expected to reach 11 billion, according to the United Nations. As oceans swell from melting sea ice and coastlines are pushed inland, the sea water will ruin fertile land, making it more difficult for nations to feed that many people. And landmass available to live on will be diminished.
The researchers at Cornell estimate that these issues, exacerbated by climate change, will create 1.4 billion refugees by 2060. Geisler said that number could reach 2 billion by 2100.