New study finds that for every 1.8 degrees Fahrenheit of global average warming, 1 billion people will have to adapt, move, or die.

  • The study, published in the Proceeding of the National Academy of Sciences on Monday, found that global warming will push billions of people outside a climate range that has sustained society for 6,000 years.
  • The study examined the history of global temperature, human population and land-use estimates from the mid-Holocene period, starting about 6,000 years ago, to 2015.
  • They found that people, crops and livestock have heavily concentrated in a narrow band of relatively constrained climate conditions in a range called the “climate niche”. The range has remained relatively unchanged for 6,000 years.
  • Ultimately, in the next 50 years a climate shift would leave 1-3 billion people outside the climate niche.
  • The study is the first of its kind to show what the optimum climatic conditions for human society have been across the past millennia.