SOURCE: Inside Climate News

DATE: May 4, 2020

SNIP: By 2070, the world’s habitable climate zone will shift so much that billions of people will be pushed past human comfort levels.

A new study published Monday in the Proceedings of the National Academy of Sciences shows a “surprisingly narrow” human climate niche—between 52 degrees Fahrenheit to 59 degrees Fahrenheit. And it will shift geographically more in the next 50 years than any time during the past 6,000 years. As a result, up to 3 billion people are “likely to live under climate conditions that are warmer than conditions deemed suitable for human life to flourish,”, the international team of researchers wrote.

Los Angeles and Paris will bake in fiery desert temperatures, and the world’s most populous cities in Asia and Africa will have deadly heat waves every year.

“It looks unlivable for many,” said co-author Tim Lenton, director of the Global Systems Institute at the University of Exeter. “Where we are headed is a place we don’t want to go.”

Some cities in North America and Europe that are now in the sweet spot of the human climate zone, with mean annual temperatures from 64 degrees and 68 degrees Fahrenheit, will be as warm as the North African coast by late in the century, Lenton said.

“That’s quite a climate shock. We’re going back to temperatures that we haven’t seen for 5 million years, territory that predates the divergence of humans from apes,” he said.

Compounding the climate problem for humans is that the greatest population growth is expected exactly in those zones most affected by human-caused warming. If the inhabitants do not migrate to more livable areas, the researchers projected, one-third of the global population will experience a mean annual temperature warmer than 84 degrees Fahrenheit—an average currently found only on 0.8 percent of the Earth’s land surface, mostly concentrated in the Sahara.

Land areas are warming faster than the oceans, which mean “human-experienced temperatures are projected to rise by about 13 degrees Fahrenheit, more than twice the mean global temperature rise,” said co-author Marten Scheffer, with Wageningen University and Research.

The buildup of heat and population could make the human climate bubble burst.

“When you talk about the most extreme temperature end, put simply, one can adapt by having good air conditioning and importing your food. That is an unlikely option for the poorest portion of humanity who happen to be the ones most exposed to extreme conditions,” he said.