Le changement climatique pourrait pousser un tiers de l’humanité à migrer d’ici 2100


Extreme heat, drought, floods, rising sea levels…, global warming is a reality and its effects are already being felt. Every year, extreme weather phenomena increase across the world and their economic, social and environmental consequences are already being felt! In the coming decades, many parts of the world will have become uninhabitable, pushing populations to migrate to warmer areas.

If the figures vary from one study to another, the observation remains the same: migratory flows linked to climate change will increase considerably. The most pessimistic scenarios (3.6°C and 4.4°C of warming) even predict that half of the world’s population will be pushed to migrate before the end of the century! Humanity would then have to face a existential risk.

It is therefore essential to do everything to keep global temperatures below the threshold of 1.5°C set by the Paris Agreement!

The human climatic niche, a disappearing comfort zone

Where do these estimates come from? Work published in May 2023 in the journal Nature Sustainabilityon the theme of “Quantifying the human cost of global warming”.

This new study, with an evocative name, offers a method for quantifying humans likely to be excluded from the “human climatic niche”. In simple terms, the human climatic niche is our comfort zone, that is to say the one which has favored the development of humanity in conditions acceptable from a climatic, but also ecological and physiological point of view.

If throughout its history, man has adapted to numerous climates, the study reveals that this comfort zone is between 13°C and 27°C average annual temperature. Supporting evidence, researchers note that living outside this range “may lead to increased morbidity, mortality, local adaptation or migratory flows”, for multiple reasons.

Climate migration is already a reality!

The study also gives a figure which sums up very well the situation in which humanity currently finds itself: climate change has already pushed 9% of the world’s population outside of this area!

For its part, the UN mentions on its website the figure of 21.5 million annual displacements linked to climatic events, or 2 to 3 times more than migrations caused by conflicts and violence.

Although this reality is difficult to estimate, certain facts should alarm us. For example, in Iraq, one of the five countries most affected by climate change in the world, entire villages are being emptied of their inhabitants due to drought and extreme temperatures.[1]. The phenomenon is such that the UN considers Iraq as an alarm signal for the planet. It must be said that the symbolic importance is particularly strong, since modern Iraq corresponds to the Fertile Crescent, the cradle of civilization and agriculture!

Other highly populated countries with hot climates such as India, Nigeria, Pakistan, Indonesia and the Philippines are also particularly affected by heat and deadly floods, and will be more and more so.

What scenarios for the future?

If the current observation is already alarming, the study proposes different scenarios for the future. Let’s be clear, with current policies, the Paris Agreement threshold of 1.5°C is expected to be exceeded by 2040 and we will reach 2.7°C of warming before the end of the century, pushing a third of the planet outside the zone of “human habitability”. In the worst scenarios (between 3.6°C and 4.4°C), even half of the world’s population would be excluded and therefore pushed to move to cooler areas.

We therefore have an interest in act without further delayby massively reducing our consumption of fossil fuels, the responsibility for which was finally officially recognized at COP28, despite the non-binding nature of the final agreement.

This study also has the merit of providing a very clear human dimension, to motivate this transition: each increase of 0.1°C will push 140 million people out of the human climatic niche. Figures which give concrete value to the actions which must be undertaken.

[1] In August 2023, temperatures were close to 50°C!

Image credit of one: jcomp – freepik


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