Too hot to live? It's just the beginning, uninhabitable areas will triple this century

In some parts of the world, going outside in the summer is already a high-risk mission: the air is burning and the body struggles to stay cool. For many, this is not a distant or theoretical problem. According to scientists, if the average global temperature rises just half a degree more, the uninhabitable land surface will triple , reaching an area equivalent to the size of the United States.

Experts warn that even a 2°C global rise will make vast regions of the Earth uninhabitable. The cause? Extreme heat, that silent enemy that can kill us without us even realising. We have already reached a 1.5°C increase, and the consequences are being felt in every corner of the planet.

If we do not drastically reduce greenhouse gas emissions, the future looks bleak. At a 4-degree rise, 40% of the Earth's surface would be uninhabitable. And at 5 degrees, extreme heat would put the lives of the entire population at risk, regardless of age.

Extreme heat: a physiological limit

Our bodies have mechanisms to deal with heat: we sweat, we seek shade, we hydrate. But there is a point at which these mechanisms are no longer sufficient. It is called "uncompensated heat" and occurs when the body receives more heat than it can dissipate, which can lead to lethal heat strokes.

Already, some regions have experienced extreme heat events that challenge the human body’s ability to regulate temperature. The Persian Gulf, the Indo-Gangetic Plain, the southern United States, Mexico, and Australia have all recorded events that exceed limits that are unbearable even for healthy young adults. With 2°C of global warming, these conditions will become much more common and will disproportionately affect older adults and children , who are especially vulnerable to extreme heat.

From extreme heat to deadly heat

When core body temperature reaches 42°C in less than six hours, the body shuts down and the outcome is lethal . This threshold, which scientists define as unbearable heat, could become a reality in several regions of the planet if global temperatures rise by 2°C above pre-industrial levels.

If we continue to burn fossil fuels unchecked and destroy carbon-absorbing ecosystems, we could face a 4-5°C increase in global temperatures, a scenario in which lethal heat will not discriminate between ages and will put entire populations at risk, especially in the tropics, where 40% of humanity now lives.

What can we do?

The message from scientists is clear: limiting global warming is the only way to avoid a world where being outdoors poses a health risk. To achieve this, it is crucial to reduce greenhouse gas emissions, invest in renewable energy and protect natural carbon reserves, such as forests and wetlands.

But it's also time to prepare for the inevitable. "As more parts of the planet experience outdoor conditions that are too warm for our physiology, it will be essential that people have reliable access to cooler environments to protect themselves from the heat," warns climate scientist Tom Matthews of King's College London.

In other words, the future that awaits us depends on what we do now. If we continue to ignore the problem, millions of people will see their homes turned into uninhabitable ovens. But if we act urgently, we can still avoid the worst of these predictions. Time, like heat, does not wait.

News reference:

Tom Matthews, Colin Raymond, et.al. “ Mortality impacts of the most extreme heat events” , Nature Reviews Earth and Environment.