Global warming is causing drastic changes in the planet's habitability, leading to potential large-scale reorganizations of where people live.
That is the conclusion of a recent study published in the journal Nature Sustainability, led by Tim Lenton, director of the Global Systems Institute at the University of Exeter, in England.
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Global warming
According to the study, if global warming is not limited to the target established by the Paris Agreement of 1 °C, more than 2 billion people, or about 22% of the projected world population, will be at risk by 2100.
However, reducing warming to 1°C would drastically reduce the number of people affected to less than half a billion, approximately 5% of the estimated global population of 9.5 billion people.
An increase of less than 1.2°C in warming so far has intensified the occurrence of heat waves, droughts and wildfires. forests, amplifying their impacts beyond what would be expected without the carbon pollution generated by burning fossil fuels and logging.
According to Lenton, the costs of global warming go beyond the financial and have a phenomenal human impact.
For every 0.1°C rise above current levels, an estimated 140 million additional people will be exposed to dangerous heat conditions.
The so-called “dangerous heat”
The research also identified that a mean annual temperature (MAT) of 29°C is considered the threshold for “hazardous heat”.
Human communities have historically been denser in regions with two distinct MATs: 13°C (temperate zones) and 27°C (tropical climates).
However, regions already close to the 29°C threshold are at greater risk of experiencing lethal heat.
According to the survey, the countries with the highest number of people facing deadly heat in this scenario are India (600 million), Nigeria (300 million), Indonesia (100 million), Philippines and Pakistan (with 80 million each).
Studies indicate that sustained temperatures at this threshold or beyond are linked to higher mortality, lower labor and crop productivity, and increased conflicts and illnesses infectious.
Over the past 40 years, the number of people exposed to extremes of heat has increased significantly, and this increase will continue for decades to come.
The regions most affected by extreme heat are close to the equator, where human populations are growing the fastest.
These locations face greater challenges due to high humidity, which prevents the body from cooling through sweating.