According to researchers, the current policies aimed at limiting global warming will have dire consequences, exposing over a fifth of humanity to extreme and potentially life-threatening heat by the end of this century. The surface temperature of our planet is projected to rise by 2.7 degrees Celsius above preindustrial levels by 2100. This increase will push more than two billion people, which accounts for 22 percent of the projected global population, outside the climate comfort zone that has sustained our species for thousands of years.
These alarming findings were published in the journal “Nature Sustainability.” The countries that will be most affected by deadly heat in this scenario include India with 600 million people at risk, Nigeria with 300 million, Indonesia with 100 million, and the Philippines and Pakistan with 80 million each. Lead author Tim Lenton, who is the director of the Global Systems Institute at the University of Exeter, emphasized the profound impact this would have on the habitability of our planet’s surface, potentially leading to large-scale reorganization of human settlements.
However, capping global warming at the target set by the 2015 Paris Climate Treaty, which is 1.5 degrees Celsius, could significantly reduce the number of people at risk to less than half a billion, equivalent to five percent of the projected 9.5 billion global population. These findings highlight the urgent need to address the climate emergency and its human costs.
The repercussions of global warming are not just financial but also have a profound impact on human lives. For every 0.1 degree Celsius of warming above current levels, an additional 140 million people will be exposed to dangerous heat. The study defines “dangerous heat” as a mean annual temperature (MAT) of 29 degrees Celsius.
Throughout history, human communities have thrived in regions with two distinct MATs: 13 degrees Celsius in temperate zones and, to a lesser extent, 27 degrees Celsius in tropical areas. However, with global warming, the risk of crossing the lethal heat threshold is significantly higher in regions that are already close to the 29 degrees Celsius mark.
Studies have shown that sustained high temperatures at or beyond this threshold are associated with increased mortality, reduced labor productivity, decreased crop yields, and a higher likelihood of conflict and infectious diseases. Shockingly, only 40 years ago, a mere 12 million people worldwide were exposed to such extreme heat. This number has now multiplied five-fold, and it is expected to rise even further in the coming decades.
The regions most vulnerable to extreme heat are often those straddling the equator, where population growth is most rapid. In these tropical areas, even lower temperatures can become deadly due to high humidity, which inhibits the body’s ability to cool down through sweating. Since 1979, episodes of extreme humid heat have doubled.
Moreover, those most affected by extreme heat are predominantly located in poorer countries that have the smallest per capita carbon footprints. For instance, India emits an average of about two tons of CO2 per person annually, while Nigerians emit half a ton per person. In comparison, the European Union emits less than seven tons per person, and the United States emits 15 tons per person, highlighting the inequality in carbon emissions.
While carbon-cutting pledges have been made by governments and companies, the actual implementation of these measures has been limited. Fulfilling these commitments could halt the rise in global temperatures at or even below 2 degrees Celsius, preventing catastrophic levels of heat and providing relief to hundreds of millions of people.
However, it is essential to note that scenarios worse than the projected 2.7 degrees Celsius increase cannot be ruled out. The authors of the study caution that if past and ongoing emissions trigger the release of natural carbon stores, such as permafrost, or if the atmosphere warms more than anticipated, temperatures could rise by nearly four degrees above the levels recorded in the mid-19th century. This is an alarming prospect that underscores the need for immediate and decisive action.
The urgency of addressing climate change and its impact on human lives cannot be overstated. It is not merely an environmental issue; it is a matter of justice and equity. The individuals and communities most vulnerable to the devastating effects of extreme heat are often the ones who have contributed the least to the carbon emissions causing global warming. It is profoundly unjust that those with the smallest carbon footprints bear the heaviest burdens of climate change.
To prevent a future marked by catastrophic heatwaves and widespread suffering, we must prioritize sustainable and equitable solutions. This includes transitioning to renewable energy sources, implementing effective policies to reduce carbon emissions, and supporting the most vulnerable communities in adapting to the changing climate.
The findings of this study serve as a wake-up call to individuals, governments, and businesses around the world. We cannot afford to be complacent or delay action any longer. The time to act is now, and we must do so with a sense of urgency and responsibility. Our collective future depends on it. Together, we can work towards a more sustainable and resilient world, where every person has the opportunity to thrive in a safe and habitable environment.