Climate change could bring near-unliveable conditions for 3 billion people, say scientists
19% of the world’s land mass could suffer temperatures on a par with the hottest parts of the Sahara
Up to 3 billion out of the projected world population of about 9 billion could be exposed to temperatures on a par with the hottest parts of the Sahara by 2070, according to research by scientists from China, US and Europe.
However, rapid reductions in greenhouse gas emissions could halve the number of people exposed to such hot conditions. “The good news is that these impacts can be greatly reduced if humanity succeeds in curbing global warming,” said study co-author Tim Lenton, climate specialist and director of the Global Systems Institute at Exeter university.
The report highlights how the majority of humans live in a very narrow mean annual temperature band of 11C-15C (52F-59F). Researchers noted that despite all innovations and migrations, people had mostly lived in these climate conditions for several thousand years.
“This strikingly constant climate niche likely represents fundamental constraints on what humans need to survive and thrive,” said Professor Marten Scheffer of Wageningen University, who co-ordinated the research with his Chinese colleague Chi Xu, of Nanjing University.
To visualize how liveable the earth will be in 2070 under these scenarios, the Financial Times has paired the population projections with each climate model and mapped them across six continents.
The respective models “are developed without accounting for feedback between each other,” explained Jing Gao, assistant professor of geospatial data science at the University of Delaware.
In the so-called shared socio-economic pathways (SSPs), “we talk about different societal trends, including population, economic development, governance, and other related aspects — but they do not already account for how people will react to climate change,” she said.
All the scenarios are idealized futures, she noted, but this is a common practice with scenario analysis. “They are all possible while sometimes reflecting extreme cases. Using several widely diverging scenarios together help capture the range of uncertainty.”