May 13 (UPI) — The World Economic Forum warned Wednesday that one-third of the world’s population could be living in locations as hot as the Sahara desert in the next 50 years if world leaders don’t take “decisive action” on climate change.

The WEF’s findings are based on the research of a team of scientists who studied global temperatures over the past 6,000 years. Their research was published in the Proceedings of the National Academy of Sciences earlier this month.

The organization said that most humans live within a “narrow band” of environmental conditions on earth, but rising global temperatures could threaten those conditions.

The WEF’s senior writer, Sean Fleming, noted that this band of climactic fluctuations has an average annual temperature of 55.3 degrees Fahrenheit.

“And the crops, livestock and irrigation that are the bedrock of the planet’s food production system were developed, discovered and designed within those constraints,” he wrote in a blog post.

These critical systems, Fleming said, can’t operate normally outside those normal environmental conditions, like those in the hottest part of the Sahara desert in northern Africa.

Those hottest parts of the desert in northern Africa account for less than 1 percent of the Earth’s land surface. But those conditions will spread to about 20 percent of the land surface if global warming is left unchecked.

The study also noted that by 2070, population growth is expected to be greatest in already-hot locations on earth. The areas hardest hit by the rising temperatures will be Africa, South America and Australasia.

Oxfam has said that climate-fueled natural disasters have pushed more than 20 million per year out of their homes over the past decade. Mass migration could increase the burden on host countries.

“This study underscores why a holistic approach to tackling climate change that includes adapting to its impacts, addressing social issues, building governance, and empowering development as well as compassionate legal pathways for those whose homes are affected, is crucial to ensuring a world in which all humans can live with dignity,” said Marten Scheffer, a professor at Wageningen University who coordinated the research.