History Lessons: If Sea Levels Rose 100 Meters, What Would Survive of Us?

The Science Behind a 100-Meter Sea Level Rise

A 100-meter rise in sea levels is nothing short of cataclysmic. To put this in perspective, the current sea level rise projections for the next century are measured in centimeters, not meters. For sea levels to climb this high, nearly every glacier on the planet would need to melt, including the massive Greenland and Antarctic ice sheets. The amount of water released would be enough to drown not only coastal cities but entire countries. Such a scenario is not currently predicted by scientists, but it’s a powerful thought experiment that reveals just how vulnerable our civilization is to nature’s might.

The Dramatic Remapping of Continents

If sea levels surged by 100 meters, the very outlines of our continents would be redrawn. Iconic landmasses like Europe and Southeast Asia would be largely submerged, leaving behind only scattered islands where mountain ranges once stood. North America would lose its coasts, with states like Florida and most of California disappearing beneath the waves. In Africa, vast inland seas would form. Australia would shrink dramatically, while only the highest peaks in South America would remain above water. The world map as we know it would be lost, replaced by a new, unfamiliar geography.

Cities Lost to the Depths

The majority of the world’s great cities are located near coasts, rivers, or deltas—areas that would be the first to vanish. Imagine Paris, London, New York, Shanghai, and Mumbai, all disappearing beneath the ocean’s surface. Their skyscrapers, monuments, and bustling streets would become underwater relics. The loss would go beyond infrastructure; centuries of culture, history, and human achievement would be erased in a matter of years. Only cities built far inland or high in the mountains would be spared, standing as lonely reminders of a world that once was.

Survival in the Highlands

As the sea advanced, humanity’s last refuges would be the world’s mountain ranges. The Andes, Rockies, Himalayas, and Alps would become crowded sanctuaries for those who managed to escape the flood. Life here would be harsh and unforgiving, with limited arable land and resources. Communities would need to adapt rapidly, learning to live in unfamiliar climates and terrain. The population would shrink dramatically, with survival depending on ingenuity, cooperation, and a willingness to abandon old ways of life. Ancient highland villages might suddenly become bustling centers of civilization.

What Happens to Our Technology?

Much of our technological infrastructure is concentrated in low-lying areas. Power plants, communication lines, data centers, and factories would all be submerged, cutting off the backbone of our digital world. The internet, as we know it, could collapse under the strain. Satellites might still orbit above, but without ground stations, their usefulness would be limited. Survivors would need to reinvent technology using whatever resources remained in the mountains. Simple tools might once again become the norm, as advanced manufacturing would be nearly impossible in the chaos following such a disaster.

Nature’s New Order

As humans retreated, nature would reclaim the newly formed coastlines. Fish and marine mammals would explore drowned cities, while coral reefs could grow on the skeletons of skyscrapers. Jungles and forests would slowly creep down the slopes, filling the void left by human civilization. New species might emerge to exploit these novel environments. The loss of so many people and cities could actually give the planet a chance to recover from centuries of pollution and deforestation, leading to a wild and unpredictable new ecological balance.

The Fate of Our History and Culture

Museums, libraries, and archives—almost all are situated in vulnerable locations. Priceless artifacts, books, and art would be lost forever, locked away in underwater tombs. Oral traditions and memories would become more important than ever, passed down by the survivors as they struggled to remember the world that was lost. Some cultures, especially those already living in highlands, might fare better, preserving their stories and traditions. But the richness and diversity of human history would be deeply diminished, with much forgotten beneath the waves.

Economic and Political Upheaval

Governments would face unprecedented challenges. Borders would vanish, economies would collapse, and the scramble for habitable land would fuel conflict. Resources like fresh water, food, and shelter would become fiercely contested. New alliances might form among mountain communities, while old political structures would fade away. Money and property would be meaningless in a world where survival depended on immediate needs rather than abstract wealth. Leadership would pass to those who could organize, protect, and provide for shrinking bands of survivors.

How Would People Adapt and Survive?

Survival would require radical adaptation. Old occupations—bankers, marketers, software developers—would be replaced by farmers, builders, and healers. Communities would need to learn forgotten skills, such as foraging, hunting, and crafting shelter from the materials at hand. Social structures would shift toward tight-knit groups, where cooperation and mutual support were crucial. New myths and legends would emerge, shaped by the memory of the great flood and the struggle to build a new life at the edge of survival.

Lessons for Our Future

The scenario of a 100-meter sea level rise is extreme, but it forces us to confront uncomfortable truths about our fragility. It is a stark reminder that the balance we depend on is delicate and can be upended by forces beyond our control. If we are to ensure that something of us survives—our knowledge, our culture, our spirit—we must respect the power of nature and act to protect the world we have. The choices we make today will echo into whatever future remains, above or below the rising tide.