Nomad Century

Nomad Century Plot Summary

Introduction

As the 21st century unfolds, humanity faces an unprecedented challenge: the mass migration of billions of people due to climate change. In the global south, extreme heat and rising seas will render vast regions uninhabitable; meanwhile, northern economies will struggle with workforce shortages and aging populations. Within the next fifty years, hotter temperatures and increasing humidity will make large portions of the planet lethal for 3.5 billion people. We have all witnessed the streams of climate refugees fleeing drought-hit areas in Latin America, Africa, and Asia, but this is merely the beginning of a planetary drama that will reshape our world. This great upheaval demands a dynamic human response. Migration has always been humanity's adaptive strategy for survival, yet our modern world has erected unprecedented barriers to human movement. The solutions lie within our grasp - we need to help people move from danger to safety, building a more resilient global society for everyone's benefit. Human movement on a scale never before seen will dominate this century and remake our world. It could be a catastrophe or, managed well, it could be our salvation. The choice is ours, and the time to prepare is now.

Chapter 1: The Uninhabitable Earth: Four Horsemen of the Anthropocene

Our planet is heating at an alarming rate. The amount of carbon dioxide in the atmosphere, which reached 420 parts per million in 2022, is higher than it's been for at least the past 3 million years. We are warming the Earth beyond anything humans have experienced during our entire evolutionary history. Only the Cretaceous-Paleogene meteorite impact 66 million years ago caused more rapid climate change than our current human-induced global heating. Four horsemen of the Anthropocene - fire, heat, drought, and flood - will transform our world this century. Fire is already devastating landscapes from Australia to California, Siberia to the Amazon. The 2019-2020 "Black Summer" in Australia burned over 3 billion animals in one of the worst ecological disasters in modern history. Heat is even deadlier - the world now experiences twice as many days over 50°C than thirty years ago. When combined with humidity, temperatures become lethal because our bodies cannot cool through sweating. By 2070, some 3.5 billion people in the tropical belt will regularly experience temperatures as hot as the Sahara. Drought will affect agriculture worldwide, with one-third of global food production threatened by climate change this century. Finally, floods from rising seas and extreme precipitation will force hundreds of millions from their homes. These four horsemen are not equal in their destruction. While fire gets the headlines for its sheer power and violence, heat is more deadly. Exposure to extreme urban heat has tripled since the 1980s, with a fifth of the world's population already affected. By 2100, climate change will be as lethal, per capita, as all infectious diseases combined are today. The most intense hazard from extreme future heatwaves is concentrated around densely populated regions of the Ganges and Indus river basins, a South Asian region inhabited by about one-fifth of the global human population. At 4°C of warming - a scenario we are currently tracking toward - the world would be unrecognizable. Sea levels would rise by at least two meters by 2100, with much more to come as ice sheets continue to melt. A wide equatorial belt would become uninhabitable for much of the year. Desert conditions would stretch from the Sahara through south and central Europe. The Amazon rainforest would likely transform into grassland. Food production would collapse in many regions, while the oceans would experience massive die-offs of marine life. This is not a distant future problem. We are already at 1.2°C above pre-industrial temperatures, and the effects are being felt worldwide. The question is not whether mass migration will occur, but how we will manage it. Migration is not the problem; it is the solution.

Chapter 2: Migration as Human Nature: Our Evolutionary Survival Strategy

Migration is woven into the very fabric of what makes us human. For hundreds of thousands of years, our ancestors developed the adaptability to live anywhere on Earth, making us the planetary primate. Unlike other species that evolved to fit specific environmental niches, humans gained the remarkable ability to thrive across diverse environments through our exceptional social cooperation and cognitive flexibility. Our early ancestors were nomadic hunter-gatherers who followed food sources and favorable conditions. They relied on group collaboration, building webs of cooperative agents to spread risk and energy costs when moving far from their original evolutionary niche. This was especially crucial during the Pleistocene era, when mile-thick ice sheets covered northern regions and fearsome predators roamed the landscapes. What set humans apart was not just our ability to move ourselves, but to move resources - carrying water, tools, and food across inhospitable terrain to bridge sparse areas and make longer journeys possible. The next evolutionary leap came when humans combined collaboration with resource movement through trade. This dramatically reduced the energy costs of resource acquisition and the risks of starting life in new locations. By exchanging materials over great distances, our ancestors could migrate further and longer, eventually leaving Africa to colonize Asia, Australia, Europe, and the Americas. This ability to exchange resources among supportive networks may have given Homo sapiens the edge over other now-extinct human species like Neanderthals. Hunter-gatherer societies developed sophisticated social systems, separating into bands during hunting seasons and coming together for festivals where meat, stories, and other resources were exchanged. The !Kung peoples of the western Kalahari, for instance, devoted substantial time to making tradeable valuables like ostrich-shell jewelry, which they exchanged for migratory rights to another group's territory. These networks helped ancient groups migrate by spreading environmental risks - if water holes dried in one tribe's territory, they could acquire food through exchange with another tribe. Migration diversified our genes and culture. In northern Europe alone, three key mass migrations during the Stone and Bronze Ages dramatically altered the genetic makeup of all Europeans. The Yamnaya steppes people, who were the first to domesticate horses, conquered and colonized Europe some 5,000 years ago, bringing their Indo-European language and advanced metalwork. Within a couple of centuries, this migration had revolutionized European society, culture, and genes, ushering in the Bronze Age. Throughout human history, migration has continued to shape our world, sometimes involving large populations, sometimes just a few people. It has distributed people across Earth's landscapes, spreading our genes, cultural practices, beliefs, and technologies. Migration is not simply a feature of human societies - it is essential to our survival and flourishing as a species.

Chapter 3: Borders and Barriers: The Myth of National Identity

The idea of keeping foreign people out using borders is relatively recent in human history. For most of our past, states were far more concerned about stopping people from leaving than preventing their arrival. They needed labor and taxes. In Roman times, laws kept peasants bound to their farms. China required "zhuan" documents for any movement around the country. Similar restrictions existed across medieval Europe. The concept of passports as we know them today, and the strict control of borders, only emerged in the late 19th and early 20th centuries. National identity itself is a modern invention. Before the end of the 18th century, an individual's nationality had little political meaning. People had ethnic and cultural identities, but these didn't define the political entity they lived in. Most people defined themselves "vertically" by who their rulers were, not by horizontal connections to fellow citizens. Eastern European immigrants arriving in the US in the 19th century could say what village they came from but not often which country - it simply didn't matter to them. Nation states as we know them today were pioneered by Latin American revolutionaries and French revolutionaries. In 1800, almost nobody in France thought of themselves as French, and only about 10% could even speak the language. By 1900, they all did. After World War I, with the end of multinational empires in Europe, state borders were redrawn along linguistic and cultural lines, and the nation state became the norm. Most of the world's 200 nations, which we consider immemorially set in stone, were created when the global population was less than one-quarter of today's. The development of nationalism required bureaucracy. Greater government intervention in people's lives and the creation of a broad systemic bureaucracy forged national identity in citizens. For instance, Prussia began paying unemployment benefits in the 1880s, which required a new layer of bureaucracy to establish who was Prussian and therefore entitled to benefits. This resulted in citizenship papers and controlled borders. As governments exerted greater control, people got more state benefits from their taxes and more rights, such as voting, which engendered a feeling of ownership over the state. Today, from Europe to Asia to the US, we are experiencing a period of potent hostility to immigrants. Promises to reduce immigration and strengthen borders have been vote winners even for liberal governments. Meanwhile, populist leaders have become ever more draconian in their dealings with foreign workers and refugees. The irony is that migration would benefit everyone - economically, socially, and culturally. Opening borders could increase global GDP by between 100 and 150 percent, adding at least $90 trillion annually to the world economy. As we face the climate crisis, the contradiction becomes stark: we've created artificial barriers to human movement at precisely the moment when migration is most needed for our collective survival. These borders, based on the myth of pure national identity, are not just morally questionable - they're pragmatically disastrous as we confront humanity's greatest challenge.

Chapter 4: Economic Benefits: How Migration Creates Prosperity

Migration is an economic powerhouse that remains largely untapped due to political barriers. Migrants contribute far more than they take out of societies - they expand economies, drive innovation, and create wealth. Currently, migrants contribute around 10% of global GDP or $6.7 trillion - some $3 trillion more than they would have produced in their origin countries. According to economist Bryan Caplan, opening borders would lead to "the rapid elimination of absolute poverty on Earth," because people would be able to move to locations with earning opportunities. The evidence contradicting anti-immigration arguments is overwhelming. Numerous studies have examined the effect of immigration on wages and employment, and the evidence shows that even large waves of low-skilled migrants have no negative impact on the wages or employment prospects of native populations - and often have a positive impact. When Cuban refugees suddenly arrived in Miami in 1980, increasing the labor force by 7%, economist David Card found that natives' wages were not adversely affected. Similar studies from France, Israel, Denmark, and across the United States have concluded the same. Why doesn't immigration hurt wages? First, the increase in the supply of workers is offset by the increase in demand for workers, as migrants spend money on goods and services that boost businesses. Second, immigration triggers reorganization of the labor market, which benefits natives. Generally, low-skilled immigrants get manual jobs, while native workers with local language skills are upgraded to non-manual jobs with higher wages. Third, most jobs available to immigrants are ones that natives don't want to do, which oils the wheels of the wider economy. Migrants also bring exceptional talents and entrepreneurship. Immigrant-founded companies account for more than half of the top twenty-five American firms and many of the most recognizable brands, including Google, Yahoo!, Kraft Foods, and Tesla. Silicon Valley is the Geneva of technology: half of the companies' founders are immigrants, as are two-thirds of the workforce. Henry Ford was the son of immigrants, Steve Jobs's father was from Syria, and the Pfizer vaccine against Covid-19 was developed by Turkish immigrants to Germany and Hungarian immigrants to the US. Migration also benefits the countries migrants physically leave behind. The networks that migrants forge help with technology transfer, trade, investment, and the transfer of institutions and norms that foster growth. Remittances sent home by migrants often exceed what developing countries receive in aid by 2.5 times on average. Nigeria, for instance, received $24.3 billion in 2018 from its emigrants working abroad - eight times what it got in development aid and more than ten times what it received in foreign investment. The demographic crisis facing many wealthy nations makes migration even more essential. Europe's population is set to shrink by 10% by 2050, with the elderly and children outnumbering workers by one-fifth by 2060. Germany alone would need to bring in at least 500,000 migrants each year just to offset that. By 2050, the EU will need 80 million extra workers, the US will need 35 million, and Japan will need 17 million to maintain existing living standards and social support systems.

Chapter 5: New Northern Cities: Rebuilding Civilization in Habitable Zones

As the planet heats, the geographical position of our species' temperature niche is shifting northwards, and people will follow. The optimum climate for human productivity - the best conditions for both agricultural and non-agricultural output - is an average temperature of 11°C to 15°C. This global niche is where human populations have concentrated for millennia. By 2100, this niche will have moved significantly poleward. North of the 45°N parallel will be the twenty-first century's booming haven: it represents 15% of the planet's area but holds 29% of its ice-free land, and is currently home to a small fraction of the world's aging population. Inland lake systems, like the Great Lakes region of Canada and the US, will see a huge influx of migrants. Cities like Duluth in Minnesota, Minneapolis, and Madison are likely to be desirable destinations. Further east, Buffalo in New York State, and Toronto and Ottawa in Canada look to be safer choices for migrants from the coasts. Alaska looks to be among the best places to live in the United States, and cities will need to be built to accommodate millions of migrants heading for the newly busy Anthropocene Arctic. By 2047, Alaska could be experiencing average monthly temperatures similar to Florida today. Similarly, Canada will be a key destination for our migrants, and the government is betting on it, aiming to triple the population by 2100. With a stable democracy, one-fifth of the world's freshwater reserves, and as much as 4.2 million square kilometers of newly arable farmland, Canada could be the world's new breadbasket later this century. Russia will be another net winner - its 2020 national action plan explicitly describes ways to "use the advantages" of climate warming. The country, which spreads over 10% of the planet's landmass, is already the world's biggest exporter of wheat, and its agricultural dominance is set to grow as its climate improves. By 2080, more than half of Siberia's permafrost will have gone, and the most inhospitable third of the massive Eurasian nation will switch from "absolute extreme" to "fairly favorable" for civilization. The melting of Greenland's ice sheet - the largest on Earth after Antarctica - will expose new areas for people to live, farm, and mine minerals. Nuuk, the capital of Greenland, sits just below the Arctic Circle and is already experiencing the effects of climate change. Fisheries are booming, and farmers are now harvesting new crops, including potatoes, radishes, and broccoli. According to projections, Greenland will even have forests by 2100. Building these new northern cities will be a massive undertaking. They will need to be designed for sustainability and resilience from the ground up, with housing, transport, energy, and food systems adapted to the new climate realities. The challenge will be to create dense, walkable cities that can accommodate millions of climate migrants while minimizing environmental impact. This will require unprecedented levels of planning, investment, and international cooperation - but it also presents an opportunity to build better cities than those we're leaving behind.

Chapter 6: Food and Resources: Sustaining Populations in a Hotter World

Feeding billions of people in their new homes presents one of our greatest challenges. The UN calculates we'll need to produce up to 80% more food by 2050 to feed an extra 2 billion city dwellers. Yet climate change and environmental degradation mean that many of our current farming regions will become unviable, while agriculture itself contributes significantly to greenhouse gas emissions and biodiversity loss. Our food system requires radical transformation. With limited agricultural land available, the most effective change will be adopting predominantly plant-based diets. This would immediately free up 75% of today's agricultural land and slash carbon emissions and nitrogen pollution. In wealthy nations, farming is the most polluting industry - more than oil companies. Just by replacing some of the meat in our diets, we could cut 70% of greenhouse gas emissions associated with food production. This transition is already underway. There are now a wide variety of meat substitutes made from plant and fungi proteins. Lab-grown meats will reach mass market later this decade, following huge investment in this new industry. According to a study in 2021, 80% of people in the UK and US are open to eating meat produced in a factory rather than a field. The United States could reach peak meat as soon as 2025, and within fifteen years, the rise of cell-based meat could bankrupt the US beef industry. Insects will become an increasingly important protein source. They convert feed to protein far more efficiently than livestock - crickets need six times less feed than cattle to produce the same amount of protein. Insect farming has huge potential as a sustainable animal feed and an addition to human diet. Black soldier fly larvae could be farmed in multi-story buildings around our cities, where they can make use of municipal waste streams. As migrant populations concentrate in cities in the north, agriculture will need to shift northward as well. Farming will expand into Arctic Canada, Alaska, Siberia, and Scandinavia, with cultivable areas moving as much as 1,200 kilometers north of current croplands. This has the potential to shift global geopolitics, with Russia's agricultural dominance growing as its climate improves, while traditional breadbaskets like the US Midwest suffer. New forms of food production will emerge. Seagrasses with edible seeds, algae, and kelp will become important food sources that can be grown without fresh water or fertilizer. Cities will contribute more to food production, with roof vegetable plots and vertical farms. Genetic research will help produce food with lower greenhouse gas emissions and less water use, while creating crops that are heat, drought, and salt-resistant. Water will become an increasingly precious resource. By 2050, severe water scarcity is expected in an almost continuous belt from the Iberian Peninsula in the west to Anatolia and Pakistan in the east, across southern regions of Russia, the western United States, and Mexico. City-scale underground reservoirs will need to be built even for our cities above the 45th parallel to harness and recirculate rainwater. Seawater desalination plants, powered by renewable or nuclear energy, will help coastal cities and irrigate local agriculture. The transition to this new food system will be challenging, but it offers the opportunity to create a more sustainable, equitable, and resilient way of feeding humanity. The business of making food has always been the most important human job - we've certainly made it harder for ourselves, but we do have the knowledge and technological expertise to innovate new ways of feeding ourselves through the coming crises.

Chapter 7: Planetary Restoration: Cooling Earth and Preserving Biodiversity

Restoring our planet to a livable state is essential if we are to limit the scale of migration and eventually allow people to return to regions that become temporarily uninhabitable. This restoration has two interconnected components: biodiversity conservation and climate cooling. Both are vital, and both require unprecedented global cooperation. Biodiversity loss is accelerating at an alarming rate. One-fifth of countries are at risk of ecosystem collapse. By degrading soils, diminishing forests, losing coral reefs, and poisoning rivers, we're threatening our own survival. The total weight of all human-made infrastructure now exceeds the planet's living biomass, and just 2.8% of Earth's land is intact wilderness. Some environmentalists are calling for half the planet's land to be conserved for nature, but even protecting one-third of the most important areas would prevent 70% of extinctions. One positive effect of humans abandoning large tracts of the globe through migration is that it will allow some natural restoration of lost biodiversity. Places left alone by people return to a wild fecundity surprisingly quickly. Higher levels of carbon dioxide and greater rainfall in the tropics, while problematic for humans, can benefit plant growth. Some forests, mangroves, and grasslands will revive naturally, and some animal species may see their populations restored. To cool the planet, we must first stop adding to the problem by rapidly phasing out fossil fuels. Then we need to remove carbon dioxide already in the atmosphere. This can be done through natural methods like reforestation and ocean fertilization, as well as technological approaches like enhanced weathering and direct air capture. Ocean fertilization offers excellent potential without taking precious land - adding powdered iron to ocean waters would dramatically increase phytoplankton production, sucking up carbon dioxide and reducing ocean acidification. Given what's at stake, we will likely need to deploy tools to reflect the sun's heat away from Earth to maintain global temperatures at safe levels. This form of geoengineering - including injecting reflective particles into the stratosphere - remains controversial, but may become necessary. By injecting about 10 megatons per year of sulphates into the stratosphere, we could reflect away about 1% of sunlight, keeping temperatures below 1.5°C of warming. That might be enough to avoid catastrophic sea-level rise, limit drought, forest fires, and hurricanes, and give some coral reefs a chance. Geoengineering offers us the ability to choose the temperature of our planet - and we may not agree on what that ideal temperature is. People living in the tropics may prefer a cooler temperature in which air-conditioning is unnecessary and drought is rarer, whereas people living in northern latitudes may prefer a hotter temperature once we've adapted infrastructure and built new cities there. These are key questions for global governance, requiring unprecedented international cooperation. Restoration of the planet's biodiversity and climate would end much of the upheaval. The sooner we act, the less mass migration there will be. If environmental conditions allow, humanity's great migration will not end with the move to higher latitudes and colonization of the polar regions. Rather, it will continue into the next century, as people repopulate abandoned regions. In time, as we continue our restoration, humans will once again expand from their refuges to the far reaches of the planet.

Summary

The story of climate migration is ultimately about human adaptability and cooperation. Throughout our evolutionary history, migration has been our primary survival strategy - it is woven into our DNA as a species. Now, as we face unprecedented climate disruption, this ancient solution must be deployed on a global scale. The great climate migration of the 21st century will see billions of people moving from uninhabitable regions toward more temperate zones, primarily in the northern latitudes. This represents both our greatest challenge and our greatest opportunity. The path forward requires us to dismantle artificial barriers between nations and recognize our shared humanity on a shared planet. We must develop new systems of global governance that facilitate safe, orderly migration while investing in planetary restoration. This means creating international citizenship frameworks, building sustainable cities in habitable zones, transforming our food systems, and deploying both natural and technological solutions to cool the Earth. Most importantly, we must shift our narrative around migration - from seeing it as a threat to recognizing it as humanity's salvation. By embracing our nomadic nature and cooperating across boundaries, we can not only survive the climate crisis but emerge as a more resilient, equitable, and sustainable global civilization.

About Author

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Gaia Vince

Gaia Vince is a freelance British environmental journalist. broadcaster and non-fiction author. Vince, a dual British and Australian national, is a chemist who studied at King’s College, London and then at the University of Bordeaux before undertaking a masters in engineering design. To fund her university studies, Vince freelanced as a journalist and at the Science Museum, building a tandem career which led her to leave research and take up writing full-time. She writes for The Guardian, and, in a column called Smart Planet, for BBC Online. She was previously news editor of Nature and online editor of New Scientist.

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