Current policies to limit global warming will expose more than a fifth of humanity to extreme and life-threatening heat by the end of the century, researchers recently warned.
Earth’s surface temperature is on track to rise 2.7 degrees Celsius above pre-industrial levels by 2100, pushing more than two billion people – 22% of the estimated global population – well outside the climate comfort zone that has allowed our species to thrive for millennia, scientists reported in Nature Sustainability.
Deadly heat
The countries with the most people facing deadly heat in this scenario are India (600 million), Nigeria (300 million), Indonesia (100 million), as well as the Philippines and Pakistan (80 million each) .
“It’s a profound reshaping of the habitability of the planet’s surface and could lead to a large-scale reorganization of where people live,” said lead author Tim Lenton, director of the Global Systems Institute at the University of Exeter.
Limiting global warming to the 1.5°C target of the 2015 Paris climate treaty would drastically reduce the number at risk to less than half a billion, about five percent of the 9.5 billion people likely to live on planet six or seven decades from now, according to the findings.
Just under 1.2°C of warming to date has already amplified the intensity or duration of heat waves, droughts and wildfires beyond what would have occurred without carbon pollution from burning fossil fuels and forests.
The last eight years have been the warmest on record.
“The costs of global warming are often expressed in financial terms, but our study highlights the phenomenal human cost of failure to address the climate emergency,” said Lenton.
“For every 0.1°C of warming above current levels, around 140 million people will be exposed to dangerous heat.”
The threshold for “dangerous heat” used in the new findings is a mean annual temperature (MAT) of 29 °C.
