India's Heat Nightmare: 600 million people at risk from rising temperatures

New research reveals that If we continue on our current trajectory and reach global warming of 2.7°C, approximately 2 billion people, or 22% of the projected population by the end of the century, will face dangerously hot conditions.

The study highlights the alarming human consequences of climate inaction by emphasizing how Earth's habitable climate zone is rapidly shrinking, disproportionately affecting those residing in lower carbon-emitting regions.

India would be worst affected country

According to the research, India would be the worst affected country, with an estimated 600 million people exposed to extreme heat if temperatures rise by 2.7°C compared to pre-industrial levels. However, if we can successfully limit warming to 1.5°C, one-sixth of the world's population would be saved from the threats of dangerous heat.

Despite the commitment made in the Paris Agreement to limit global warming to well below 2°C above pre-industrial levels, current policies are projected to result in a temperature rise of 2.7°C by the end of the century. The projection is based on a new study by researchers at the University of Exeter's Institute for Global Systems, in collaboration with the Earth Commission and Nanjing University.

The study aimed to assess the implications of this rise in temperature on the number of people living outside of the "climate niche," the optimal climatic conditions in which our species has historically thrived.

Currently, 60 million people are already exposed to hazardous heat, defined as an average temperature of 29°C or higher. If global warming reaches 2.7°C, this number is expected to increase significantly.

Shockingly, the study predicts that two billion people, representing 22% of the projected population by the end of the century, would be exposed to such extreme heat.

Limiting global warming to 1.5°C,

The research paper underlines the significant potential of decisive climate policies to reduce the human costs and inequalities associated with climate change. By limiting global warming to 1.5°C, only 5% of the population would remain exposed to dangerous heat, resulting in a remarkable achievement in saving one-sixth of humanity from the adverse impacts of extreme temperatures compared to a 2.7°C warming scenario.

The study reveals a striking disparity in the distribution of emissions throughout life. The emissions produced by an average of 3.5 global citizens today, or just 1.2 US citizens, are enough to subject a future individual to dangerously hot conditions.

The disparity highlights the inequity of the climate crisis, as those who will bear the brunt of future heat exposure reside in regions where current emissions are about half the global average.

Existential Risk: Global Population Vulnerability

In the most alarming scenarios of global warming, where temperatures rise by 3.6°C or even 4.4°C, the research indicates that approximately half of the global population could find themselves outside the climate niche, posing a severe existential risk, as described by the researchers.

Professor Tim Lenton, director of the Global Systems Institute at the University of Exeter, Speaking to Ground Report said that the immense human cost associated with neglecting the climate emergency. While the financial implications of global warming are often discussed, our study sheds light on the staggering toll it takes in human lives.

He added: “For every 0.1°C of warming above current levels, around 140 million more people will be exposed to dangerous heat.

Lenton further said: “This reveals both the scale of the problem and the importance of decisive action to reduce carbon emissions.

“Limiting global warming to 1.5°C instead of 2.7°C would mean five times fewer people in 2,100 exposed to dangerous heat,” he added.

Defining the niche 

Throughout history, human population densities have reached their highest levels in regions with an average temperature of about 13°C. Another density peak is observed around 27°C, particularly in monsoonal climates, predominantly in South Asia.

Similar patterns can be seen in the density of crops and livestock, as well as in the measure of wealth through GDP, which also peak around 13°C.

The relationship between temperature and human well-being is further highlighted by the fact that death rates tend to increase at both higher and lower temperatures, supporting the concept of a human 'niche'.

While less than 1% of the world's population currently resides in areas experiencing dangerous levels of heat, the study shows that climate change has already pushed more than 600 million people, representing 9% of the world's population, out of this favourable niche.

“Most of these people lived near the cooler 13°C peak of the niche and are now in the 'middle ground' between the two peaks. While not dangerously hot, these conditions tend to be much drier and have not historically supported dense human populations," said Professor Chi Xu of Nanjing University.

“In the meantime, the vast majority of people who will be left out of the niche due to future warming will be exposed to dangerous heat.

“Such high temperatures have been linked to problems including increased mortality, lower labour productivity, lower cognitive performance, learning disabilities, adverse pregnancy outcomes, lower crop yields, increased conflict, and the spread of infectious diseases.”

Heat Vulnerability: India and Nigeria

The study revealed that while certain colder regions may experience increased livability due to climate change, the greatest population growth is projected to occur in areas already susceptible to dangerous heat. In particular, India and Nigeria emerge as focal points of concern in light of their vulnerability to rising temperatures.

The study highlights a critical threshold, indicating that exposure to dangerous levels of heat begins to escalate significantly once global warming exceeds 1.2°C, just above the current global baseline. Disturbingly, for every additional 0.1°C of warming, the number of people exposed to dangerous heat conditions increases by approximately 140 million worldwide.

Projections based on a future population of 9.5 billion people indicate that India would face the largest population at risk of dangerous heat at 2.7°C of global warming, with more than 600 million people affected. However, by limiting warming to 1.5°C, this number would drop significantly to about 90 million, highlighting the critical importance of mitigating global temperature rise.

India and Nigeria already show alarming "hot spots" characterized by extreme temperatures that pose significant risks to human well-being and livelihoods. These regions are at the forefront of climate change impacts, requiring urgent attention and adaptation measures.

Effects of dangerous levels of heat on people

Speaking about the conception of his idea, Professor Marten Scheffer, from Wageningen University, said: “We were buoyed by the fact that the economic costs of carbon emissions barely reflect the impact on human well-being.

Researchers Dr. Marten Scheffer from Wageningen University and Ashish Ghadiali from the Exeter Institute for Global Systems expressed their motivation behind their idea, highlighting the discrepancy between the economic costs of carbon emissions and their true impact on human well-being. They stressed the need for their calculations to bridge this gap and raise unconventional questions about fairness and equity in climate change discussions.

The study by Dr. Scheffer and Ghadiali, at the forefront of Earth systems science, shed light on the inherent racial nature of projected climate impacts. They urged a transformative shift in political thinking, emphasizing the urgency of decarbonization efforts and the importance of increased global investment in climate-vulnerable areas.

In a recent report, the institute emphasized three crucial "super leverage points" that have the potential to start a decarbonization ripple effect. These findings offer promising avenues to drive significant progress in the fight against climate change.

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