Researchers warned Monday that current policies to limit global warming will expose more than a fifth of humanity to extreme and potentially life-threatening heat by the end of the century.
Earth’s surface temperature is expected to rise 2.7 degrees Celsius (4.8 degrees Fahrenheit) above pre-industrial levels by 2100, pushing more than two billion people — 22 percent of the projected global population — well outside the climate comfort zone that allows our species to live. scientists reported in Nature Sustainability.
The countries with the largest number of people exposed to deadly heat in this scenario are India (600 million), Nigeria (300 million), Indonesia (100 million), and the Philippines and Pakistan (80 million each).
“This could lead to a massive change in the habitability of the planet’s surface and potentially a large-scale reorganization of human habitability,” said Tim Lenton, Director of the Global Systems Institute at the University of Exeter.
As outlined in the 2015 Paris Climate Agreement, limiting global warming to 1.5°C would significantly reduce the number at risk to less than half a billion, about five percent of the 9.5 billion people likely to live on the planet sixty or seventy years from now. . Now, according to the findings.
Warming of just under 1.2°C to date has already increased the intensity or duration of heat waves, droughts and wildfires beyond what would have occurred without the carbon pollution from fossil fuels and forest burning.
“The costs of global warming are often expressed in financial terms, but our study highlights the extraordinary human cost of failing to manage a climate emergency,” Lenton said. Said.
“For every 0.1°C of warming above current levels, approximately 140 million people will be exposed to dangerous heat.”
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The “hazardous heat” threshold used in the new findings is an average annual temperature (MAT) of 29 °C. Throughout history, human societies have lived most intensely around two different MATs: 13°C (in temperate regions) and to a lesser extent 27°C (in more tropical climates).​
Global warming is raising the thermostat everywhere, but areas that are already close to the 29°C red line are clearly at higher risk of falling to deadly temperatures.
Studies have shown that high temperatures sustained at or above this threshold are strongly associated with higher mortality, lower productivity and productivity, as well as increased conflict and infectious disease.
As recently as 40 years ago, only 12 million people worldwide experienced such overexposure. The study showed that today that number has increased fivefold and will grow even faster in the coming years. The risk is increasing in areas of the equator where human populations are growing the fastest: Tropical climates can be deadly even at low temperatures, where high humidity prevents the body from cooling through perspiration.
Extreme humid heat events have doubled since 1979.
Those most exposed to extreme heat often live in poorer countries with the lowest per capita carbon emissions, the authors say.
According to the World Bank, India emits an average of about two tons of CO2 per person each year, and Nigerians emit about half a tonne of CO2 per year. States.
Unfulfilled commitments to reduce carbon emissions by governments and companies will stop global temperature rises at 2°C or below and allow hundreds of millions of people to avoid catastrophic heat. However, the authors warn that scenarios worse than the global temperature of 2.7°C due to current policies cannot be ruled out.
They say that if past and ongoing emissions trigger the release of natural carbon stores such as permafrost or warm the atmosphere more than expected, temperatures could rise about four degrees above mid-19th century levels.
Source: Port Altele
