Three billion people could live in places as hot as the Sahara desert within 50 years, the World Economic Forum (WEF) said on Wednesday.
The warning came after scientists found that a third of the world's population could be forced to endure "unliveable" circumstances by 2070 if decisive action was not taken to halt climate change.
A research team made up of experts from the U.S., China and Europe analyzed rising global temperatures, comparing them to average climatic conditions over the last 6,000 years. Their findings were published in the journal Proceedings of the National Academy of Sciences last week.
Unless moves were made to reverse the damage wreaked on the environment by greenhouse gases, one in three people could live in areas where temperatures matched the hottest parts of the Sahara today, according to the scientific study. This could become a reality within decades, the researchers found, with average temperatures for that percentage of the population projected to be above 29 degrees Celsius (84 degrees Fahrenheit).
The researchers took population growth projections into account in the study. Today, less than 1% of the earth's land surface currently experiences this climate, scientists said — but by 2070, almost 20% of the planet's land area would reach those temperatures.
Analyzing the study, WEF warned that the human race had learned to live "within a relatively narrow band of environmental and climatic fluctuations" over the past six thousand years. It noted that mean annual temperatures had stood at around 13 degrees Celsius, and warned that health, food security and economic growth would face huge challenges outside of the temperature ranges we inhabit today.
"The crops, livestock and irrigation that are the bedrock of the planet's food production system were developed, discovered and designed within those constraints," the WEF's Sean Fleming said in a blog post. "These, and other critical systems, cannot be expected to function normally outside the environmental niche they grew up in."
The worst effects of rising temperatures would be felt by some of the world's poorest communities, he warned.
According to the scientific study, by 2070 the average person will be living in temperatures 7.5 degrees Celsius hotter than pre-industrial times if climate change goes unchecked, with Africa, South America and Australasia particularly at risk. Extreme weather events could mean droughts, floods, famine and disease became the norm, the researchers warned.
Earlier this year, WEF said severe threats to the climate accounted for the top five long-term risks to the global economy.