### Environment Expansion of uninhabitable zones - Survival crisis at the beginning of the 21st century

### Environment Expansion of uninhabitable zones - Survival crisis at the beginning of the 21st century

At the beginning of the 21st century, researchers pointed out that billions of people could be locked out of the comfortable climatic conditions in which human civilization had been built, i.e., the average temperature range of 13 to 25 degrees Celsius. Without migration, a third of the world's population would be forced to live in areas with average temperatures above 29°C, and the extreme heat of the Sahara Desert was predicted to become the order of the day. This prospect was not a mere hypothesis, but a body of scientific knowledge that was already sounding serious alarm bells about the future of humankind.

At the time, the Kyoto Protocol of 1997 was in effect, and the international goal of limiting the rise in global temperatures to within 2 degrees Celsius was set. However, due to the withdrawal of the United States and the expansion of emissions in emerging countries, its effectiveness was limited and no progress was made in reducing greenhouse gases. As a result, it became difficult to control the temperature rise in reality, and heat waves repeatedly hit people in India and Pakistan, while in the Middle East, temperatures exceeding 40°C day and night became the norm. In the Sahel region of Africa, droughts have developed, and food shortages and the exodus of refugees have become international problems. These phenomena shook the world, not as future threats, but as crises that had already begun.

In addition, rapid population growth and urbanization exacerbated the situation. In large cities in South Asia and Africa, heat stroke and water shortages became serious social problems, as hundreds of millions of people were exposed to extreme heat due to weak cooling systems and power grids. Technological solutions were sought, such as the development of heat-tolerant crops, the introduction of energy-efficient building materials, and the diffusion of high-efficiency cooling technology, but inequality due to economic disparity became a barrier, limiting the number of regions that could benefit from these solutions. As a result, "migration" emerged as a practical solution, and high-latitude regions such as Canada and Scandinavia attracted attention as candidates for new settlements.

Thus, the new international issue of "climate refugees" has become a reality in the post-Cold War world order. Unlike the conventional refugee problem, the natural environment itself is forcing people out of their homes, and the international community is being forced to respond in unprecedented ways.

The expansion of uninhabitable zones has proceeded through a complex interplay of scientific alarm, demographic change, political stagnation, and the limits of technological innovation. At the beginning of the 21st century, the problem was not merely a prediction of the future, but a "survival crisis" facing humanity as a whole.