2 Billion People Exposed to Extreme Heat if Global Warming Rises to 2.7°C, Study Shows

According to a study, if global warming causes temperatures to rise by 2.7°C, as many as 2 billion people will be exposed to excessive heat.

A recent study warns that if current climate policies persist, over 20% of the global population will face dangerously high temperatures by 2100. Despite the Paris Agreement's target of limiting global warming to below 2°C, predictions indicate a 2.7°C rise by the century's end.

The research evaluates the consequences for those living outside the "climate niche" where humans have traditionally thrived.

Currently, 60 million people experience severe heat, with average temperatures exceeding 29°C. At 2.7°C of warming, a staggering 2 billion people, which is 22% of the total projected population, would be exposed to such extreme heat.

The study emphasizes the urgent need for effective climate policies to mitigate the costs and inequities of climate change. Limiting warming to 1.5°C would reduce exposure to harmful heat for 5% of the population, protecting millions from the lethal effects.

Each 0.1°C increase above current levels would expose an additional 140 million individuals to dangerous heat, underscoring the imperative of swift carbon emission reductions. Keeping warming at 1.5°C instead of 2.7°C could reduce the number of people exposed by five times by 2100.

Mortality, Severe Temperatures, and the Human Niche

Historically, the human population density peaks between 13°C and 27°C, especially in the monsoon regions of South Asia. GDP and crop and livestock densities both exhibit peaks at 13°C and comparable patterns.

Over 600 million people, which is 9% of the world's population, have already been pushed out of the human "niche" due to climate change, even though less than 1% of people are currently exposed to harmful heat.

Mortality increases at severe temperatures, confirming the idea of a human "niche." Many impacted people, who had previously lived close to the 13°C high, are now located in a less hospitable "middle ground" that has historically been less populated and drier.

Most displaced people in the future would experience dangerous heat, which is linked to higher mortality, decreased productivity, problems with memory and learning, unfavorable pregnancies, poorer crop yields, disputes, and the spread of disease.

Population growth is anticipated to be strongest in countries susceptible to severe heat, including India and Nigeria, even though some colder locations may become more habitable.

Other Findings

The study also discovered that for every 0.1°C increase in global warming, exposure to harmful heat increases by around 140 million people. This is barely above the present level of warming.

At 2.7°C of global warming, India would have the most population exposed-more than 600 million-assuming a future population of 9.5 billion. This number would be much smaller, at roughly 90 million, at 1.5°C.

At 2.7°C global warming, Nigeria would rank second in having the largest population subjected to heat, with more than 300 million people. This would be less than 40 million at a rise of 1.5°C.

There are already deadly temperature "hotspots" in Nigeria and India.

Nearly all nations, including Burkina Faso and Mali, will reach dangerously high temperatures for people at 2.7°C. Brazil would have the greatest land exposed to dangerous heat at 1.5°C while having almost no exposed acreage. Additionally, a lot more land will be exposed in Australia and India.

Positive Tipping Points and Super Leverage Points

The study's research team, which includes universities as well as organizations like the Potsdam Institute for Climate Impact Research and the International Institute for Applied Systems Analysis, emphasizes that the most serious effects can be avoided by acting quickly to reduce greenhouse gas emissions.

Their concept was born out of the observation that the economic costs of carbon emissions do not accurately represent their impact on human well-being, according to Professor Marten Scheffer of Wageningen University.

Their calculations seek to close this gap to inspire fresh and unusual dialogues on justice. The results underscore the racialized nature of anticipated climate consequences and should spur a paradigm shift in how policies are thought of and how much money is invested globally to address vulnerability to climate change.

The consequences of unsafe heat levels on people will worsen if fast and strong action is not done to reduce greenhouse gas emissions, warns Wendy Broadgate, the Earth Commission at Future Earth Executive Director, Phys Org reports.

The University of Exeter's Global Systems Institute has found positive tipping points and highlighted super-leverage points that could start a chain reaction of decarbonization and advance climate solutions.

The study by Lenton, Xu, and several colleagues was recently published in the journal Nature Sustainability.