Nomad Century: How Climate Migration Will Reshape Our World

A great upheaval is coming. It will change us, and our planet.

In the global south, extreme climate change will push vast numbers of people from their homes, with large regions becoming uninhabitable; in the planet’s more comfortable north, economies will struggle to survive demographic changes with massive workforce shortages and an impoverished elderly population.

Over the next fifty years, hotter temperatures combined with more intense humidity are set to make large swathes of the globe lethal for 3.5 billion of us. Fleeing the tropics, the coasts and formerly arable lands, huge populations will need to seek new homes; you will be among them, or you will be receiving them. This migration has already begun – we have all seen the streams of people fleeing drought-hit areas in Latin America, Africa and Asia where farming and other rural livelihoods have become impossible. Climate-driven movements are adding to a massive migration already under way to the world’s cities. The number of migrants has doubled globally over the past decade, and the issue of what to do about rapidly increasing populations of displaced people will only become greater and more urgent as the planet heats.

Have no doubt, we are facing a species emergency – but we can manage it. We can survive, but to do so will require a planned and deliberate migration of a kind humanity has never before undertaken.

People are finally beginning to face up to the climate emergency. However, while nations rally to reduce their carbon emissions, and try to adapt at-risk places to hotter conditions, there is an elephant in the room: for large portions of the world, local conditions are becoming too extreme and there is no way to adapt. The world already sees twice as many days where temperatures exceed 50°C than thirty years ago – this level of heat is deadly for humans, and also hugely problematic for buildings, roads and power stations. In short, it makes an area unliveable.

This explosive planetary drama demands a dynamic human response, and the solutions are within our hands. We need to help people to move from danger and poverty to safety and comfort – to build 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.

People will have to move to survive.

Large populations will need to migrate, and not simply to the nearest city, but also across continents. Those living in regions with more tolerable conditions, especially nations in northern latitudes, will need to accommodate millions of migrants into increasingly crowded cities while themselves adapting to the demands of climate change. We will need to create entirely new cities near the planet’s cooler poles, in land that is rapidly becoming ice-free. Parts of Siberia, for example, are already experiencing temperatures of 30°C for months at a time.

Wherever you live now, this migration will affect you and the lives of your children. It may seem obvious that Bangladesh, a country where one-third of the population lives along a sinking, low-lying coast, is becoming uninhabitable. (More than 13 million Bangladeshis – nearly 10 per cent of the population – are expected to have left the country by 2050.) Or that desert nations like Sudan are becoming unliveable. But in the coming decades wealthy nations will be severely affected too. Hot, drought-afflicted Australia will suffer, as will parts of the United States, forcing millions from cities such as Miami and New Orleans to seek safety in cooler states like Oregon and Montana. Cities will need to be built to house them.

In India alone, close to a billion people will be at risk. Another half billion will need to move within China, and millions more across Latin America and Africa. Southern Europe’s treasured Mediterranean climate has already shifted north, leaving regular desert-like conditions from Spain to Turkey. Meanwhile, parts of the Middle East have already been made intolerable by increasing heat, lack of water and poor soils.

People will begin leaving. They are already on the move.

We are undergoing a species-wide planetary upheaval and it occurs not only at a time of unprecedented climate change but also of human demographic change.

Global population will continue to rise in the coming decades, peaking at perhaps 10 billion in the 2060s. Most of this increase will be in the tropical regions that are worst hit by climate catastrophe, causing people there to flee northwards. The global north faces the opposite problem – a ‘top-heavy’ demographic crisis, in which a large elderly population is supported by a too-small workforce. At least twenty-three nations, including Spain and Japan, are expected to see their populations halve by 2100. North America and Europe have 300 million people above the traditional retirement age (65+), and by 2050 the economic old-age dependency ratio there is projected to be at forty-three elderly persons per 100 working persons aged 20–64.¹ Cities from Munich to Buffalo will begin competing with each other to attract migrants. This competition will become especially acute towards the end of the century, when some of the southern places made uninhabitable by climate change may become once again liveable through geoengineering innovations that reduce global or regional temperatures, through carbon dioxide removal and technological interventions that can cool large areas cheaply. Truly, this is the century of unprecedented, planetary human movement.

We need to plan pragmatically now, adopting a species-wide approach to ensure our human systems and communities have the resilience to weather the shocks to come. We already know which communities will need to relocate by 2050, when I will be in my seventies. We know also which places will be safest at the end of the century, when my children will be in their old age.

We need to look now at where these billions of people could be sustainably housed. Doing so will require international diplomacy, negotiations over borders, and adaptation of existing cities. The Arctic, for instance, will become a relatively habitable destination for millions of people, although the current infrastructure there, minimal though it is, is already sinking into the melting permafrost and will have to be rebuilt for the hotter conditions. Preparing for this climate migration means the phased abandonment of major cities, the relocation of others, and the building of entirely new cities in foreign lands. London, the city I live in, is at least 2,000 years old and accommodates 9 million people. We have mere decades to adapt, expand and build such cities. We can build emergency hospitals in a few days, as we saw during the Covid-19 pandemic; I’ve no doubt we can build ambitious cities within years. But what sort of cities, and where, and for whom?

The coming migration will be big and diverse. It will involve the world’s poorest fleeing deadly heatwaves and failed crops. It will also include the educated, the middle class, people who can no longer live where they planned because it’s impossible to get a mortgage or property insurance; because employment has moved elsewhere; because the neighbourhood has become undesirable because those who could have already left for a more tolerable climate. Climate change has already uprooted millions in the US – in 2018, 1.2 million were displaced by extreme conditions; by 2020, the annual toll had risen to 1.7 million people. The US now averages a billion-dollar disaster every eighteen days.² A 2021 survey of Americans who were moving home found that half cited climate risks as a factor.

As I write this, more than half of the western US is facing extreme drought conditions, and farmers in Oregon’s Klamath Basin are talking about illegally using force to open dam gates for irrigation. At the other extreme, by 2050 half a million existing US homes will be on land that floods at least once a year, according to data from Climate Central, a partnership of scientists and journalists. Those homes are valued at $241 billion. Even if a building doesn’t itself flood, if enough local infrastructure is flooded, the neighbourhood becomes unviable and people move away. Those affected will include residents of important cities, such as the 400,000 inhabitants of New Orleans. Louisiana’s Isle de Jean Charles has already been allocated $48 million of federal tax dollars to move the entire community due to coastal erosion and rising sea levels. In Britain, the Welsh villagers of Fairbourne have been told their homes should be abandoned to the encroaching sea as the entire village is to be ‘decommissioned’ in 2045. Larger coastal cities are at risk, too. Consider that the Welsh capital, Cardiff, is projected to be two-thirds under water by 2050.

For you, the coming upheaval may be a sudden, urgent exodus because climate change has devastated harvests, food prices have soared, and your country has been overtaken by violent conflict and become unsafe. Or it may be that a hurricane devastates your town, or ocean waves erode your village. The upheaval will happen suddenly, in the wake of catastrophes, and it will happen slowly, in dribs and drabs. The United Nations International Organization for Migration estimates that there could be as many as 1.5 billion environmental migrants in the next thirty years alone. After 2050, that figure is expected to soar as the world heats further and the global population rises to its predicted peak in the mid 2060s. Disasters already displace up to ten times more people than conflict and war worldwide.

We are making a new and very different world through our environmental changes. As the only sentient beings capable of such audacious planetary transformation, we must have the maturity and wisdom to direct our talents towards saving ourselves.

I’ve certainly panic-Googled land prices in Canada and New Zealand, seeking a safe place for my children’s future with reliable fresh water and greenery for the coming decades. But I have also had to accept that this is not a challenge that we can meet as individuals. For if we approach the greatest migration in a piecemeal way – in which those who can, buy safety in the least affected parts of the world – we risk an inequality of survival that threatens us all. We would face the likelihood of an enormous loss of life, of terrible wars and misery, as the wealthy erect barriers against the poorest. We see this devastating situation occurring in a far smaller way today – we cannot allow such calamitous chaos at the scale expected in a few decades. Quite apart from the moral abhorrence, there would be no peace for any of us. Instead, we must come together as a global society to address this human-made problem. We are a planetary species, dependent on a single shared biosphere. We must look afresh at our world and consider where best to put its human population and meet all of our needs for a sustainable future.

Doing so requires a radical rethink. The question for humanity becomes: what does a sustainable Promised Land look like? If we manage to achieve a commonwealth of humanity, we will continue to dominate the globe, although we and our food production will inevitably be limited to a relatively small region. We will need to develop an entirely new way of feeding, fuelling and maintaining our lifestyles in this Anthropocene era, while also reducing atmospheric carbon levels. We will need to live in denser concentrations in fewer cities, while reducing the associated risks of crowded populations, including power outages, sanitation problems, overheating, pollution and infectious disease.

At least as challenging, though, will be the task of overcoming a geopolitical mindset, the idea that we belong to a particular land and that it belongs to us. In other words, we will, as refugees of nations, need collectively to transition to a sense of ourselves as citizens of Earth. We will need to shed some of our tribal identities to embrace a pan-species identity. We will need to assimilate into globally diverse societies, living in new, polar cities. We will need to be ready to move again when needed.

With every degree of temperature increase, roughly a billion people will be pushed outside the zone in which humans have lived for thousands of years. We are running out of time to manage the coming upheaval before it becomes overwhelming and deadly. Migration is not the problem; it is the solution.