Migration is as old as humanity itself. People have been on the move since the earliest times, either voluntarily or forced into it through famine, climate change or war and conflict. Our ancestors travelled from Africa to all other parts of the world. Hunter-gatherers in prehistoric times travelled long distances in search for food. The early Middle Ages witnessed large population movements in Europe. Slavery forcibly brought millions of people from Africa to the Americas and the Middle East, and in the 19th and 20th centuries, millions of migrants from Europe sought their luck in the New World of North America, Australia and New Zealand. These are just a few examples of large population movements in the history of mankind. Today’s global population movements are therefore no exception. What differs is the scale. As of 2020, more than 280 million people are international migrants, [1]1 — United Nations Department of Economic and Social Affairs (UN DESA), Population Division (2020). International Migrant Stock 2020. which is 1.6 times more than in 2000 (173 million), and almost double the number in 1990 (153 million).

What is also on a larger scale than in the past is public attention to international migration. Social media plays an important role in public awareness of migration, but it is also a highly contentious issue in the political arena of most countries in the “Global North” (Europe, North America, Israel, Australia, New Zealand, Japan, South Korea). In this often heated debate it is not always easy to separate fact from fiction. This essay seeks to contribute to a fact-based discussion by focusing on what drives global migration. Knowledge of the main determinants of global migration may help in creating a better understanding of the phenomenon, which is important for a more balanced debate on the issue. The main drivers of global migration may be summarised as economic and demographic inequalities, and humanitarian crises. Moreover, the effects of policy is also relevant, as it can both stimulate or limit migration. Although reality is far more complex than what these factors portray, they nevertheless provide the backbone for current global migration patterns and trends and shed some light on the likely future of global migration.

Global migration trends

The 281 million migrants mentioned above make up about 3.6% of the world’s population. Migrants are defined as people born in a country other than where the currently reside. Since 1990, their population has risen by 128 million. Of this increase, 74 million is due to global population growth, and the remaining 54 million is due to the increased propensity of the global population to migrate, representing a relative increase of 35%.

The migrant population is not evenly spread over the globe. Table 1 shows the share of migrant origin and destination regions (continents) in 1990 and 2020. Asia and Europe were the largest global migrant origin regions both in 1990 and 2020. As 60% of the world population lives in Asia, its share of emigration of around 40% is relatively modest, and its share of global immigration (31%) even more so. The contribution of Europe to global migration is far higher than might be expected given its population size. Whereas Europe’s share of the world population shrank from 14 to 10% between 1990 and 2020, its contribution to global emigration was far higher, although declining fast: from 31 to 23%. The share of Europe as a destination region decreased slightly, from 32 to 31%, but that of the EU-28 countries increased from 18 to 23%. Africa’s share of the global migrant stock in 2020 (14%) was below what one would expect based on its share of the global population (17%), although in 1990 it was slightly higher. Overall, the immigration shares of the world regions have remained relatively stable over time, with the countries of the Global North being the chosen destination for more than 50% of all migrants.

These figures are based on migrant stocks: the foreign-born resident population in each country. Given the significant sensitivity regarding migration in many countries, one would expect the data on migration flows to be accurate, yet, in fact, the opposite is true. Countries use different definitions and different ways of measuring migration. As a result, estimates may differ significantly. For instance, Germany reported more than 100,000 immigrants annually from Poland in the period 2002-2009, but Poland reported only about 10-12,000 emigrants annually to Germany.

There are only 45 countries worldwide (mostly high-income countries) that collect migration flow data: persons leaving one country to reside in another over a given time period. From the limited data on flows, it is estimated that, annually between 2011 and 2018, the number of migrants entering OECD countries increased from 4 to 5 million. Estimates by Abel and Sanders (2014) show that the largest migration flows between world regions in 2005 were from Central America to North America (3.2 million), from Africa to Europe (2 million) and from South Asia to Western Asia (4.9 million). The common denominator here is that these flows are all between adjacent world regions, and from low-income to middle- and high-income countries. Acute humanitarian crises have added to these flows in recent years, particularly the large flow of more than 5 million refugees from Ukraine to Europe.

Economic inequalities

Migration is not a goal in itself, but a means to an end. Migrants move to destinations where they hope to live a better life. Although the motives for migration are diverse, striving for a better life, a job, or a better income are the primary drivers of migratory movements (Massey et al., 1993). Economic inequalities are therefore key determinants in unbalanced migration flows. The number of migrants from low-income countries living in high-income countries in 2020 was more than 10 million, whereas the opposite case, migrants from high-income countries now living in low-income countries, was only 100,000, or 1% of the previous figure. Even larger imbalances exist between middle- and high-income countries: 117 million people born in middle income countries live in high-income countries, whereas only 6 million migrants from high-income countries live in middle-income countries. [4]4 — United Nations Department of Economic and Social Affairs (UN DESA), Population Division (2024). World Population Prospects. The 2024 Revision. Available online. Similar patterns can be seen in countries within the EU: the economically best performing countries attract the most migrants (Figure 2).

Despite this obvious relationship between migration and economic development, if low-income countries develop economically into higher-income countries, this does not necessary mean that their emigration rates decrease. Research has shown that an increase in income for the lowest income countries leads to higher outmigration, [5]5 — See, for instance, De Haas, H. (2023). How Migration Really Works: A Factful Guide to the Most Divisive Issue in Politics. Random House. because more people can afford to pay the costs of migration. It is only when income levels reach a threshold that outmigration levels off. Economic development is certainly necessary for the lowest-income countries in the world, but it is not a panacea for reducing migration, as is often believed.

Income inequality between countries has dramatically increased since the 1990s. While the income gap in 1990 between high-income and low-income countries was $33,000, by 2023 it had grown to $55,000. [6]6 — Author’s own calculations based on the World Inequality Database. Available online. Wealth is increasingly concentrated in the richest countries. Nevertheless, a significant group of countries in the middle-income range has been able to narrow the gap in relative terms. Whereas high-income countries saw their income grow by 62% between 1990 and 2023, middle-income countries tripled their average income. It is therefore likely that the number of migrants from low-income countries will further increase in the future, but they may also consider more countries in the upper middle-income bracket as a destination.

Demographic inequalities

Another global division is one that separates young from old countries. Many countries of the Global North have very low birth rates and an aging population. The average number of children per woman needs to be 2.1 (the so-called replacement rate) for the next generation to exactly match the size of the previous one, but the rate in most countries of the Global North is far lower. For instance, the lowest rate is in South Korea, with 0.81 children per woman, in Europe it is 1.47, in China it is 1.24, and even India now no longer reaches the replacement level, with a rate of 2.05. In addition, the long-term consequences of the post-war baby-boom in many countries is that, since 2010 (65 years after the baby boom started), there have been more people retiring than young people entering the labour market. Moreover, many countries in the Global North experience negative natural growth (deaths exceeding births) as a result of these developments.

At the same time, in many countries in the Global South the opposite occurs. They have populations more than half of whom are under 20 years of age, because of high fertility rates. For instance, the average number of children per woman in Africa is 4.2. Although fertility is also dropping there, the very young age distribution will guarantee continued high population growth in the coming decades, as it will in Asian countries, such as India or Pakistan.

Whereas in many countries of the Global North there is growing demand for workers, in the Global South the opposite is true: economic growth is insufficient to provide enough jobs for the large supply of young workers. This picture matches what demographers call the “demographic dividend”: the potential of a large, young workforce relative to the number of dependents (children and retirees) to generate economic growth.

In this regard, schooling is very important. [7]7 — Lutz, W.; Crespo Cuaresma, J.; Kebede, E.; Prskawetz, A. P.; Sanderson, W. C.; Striessnig, E. (2019). “Education Rather Than Age Structure Brings Demographic Dividend, Proc. Natl. Acad. Sci. USA, no. 116 (26), pp. 12798-12803. Available online. Fifty years ago, South Korea and Nigeria were comparable in terms of per capita income. However, while South Korea invested heavily in educating its younger generations, Nigeria did little in this area. Today, South Korea’s per capita GDP, at 50,000 dollars, is almost the same as that of the European Union and nearly ten times higher than that of Nigeria.

Aging societies have moved beyond the stage of enjoying a demographic dividend and are now in a situation where labor force growth cannot keep pace with economic growth, which in turn may slow down the economy. Many countries in the Global South find themselves in a position where they could potentially reap the benefits of their large young workforce, but their economies are too small to absorb this vast labor reserve. As a result, many people survive on marginal jobs and minimal incomes

Migration may to some extent help to mitigate this global demographic imbalance (UN, 2000) but it will never be sufficient to solve the problems of aging societies (UN, 2000). Migration may give a boost to the development of the Global South, not because it significantly reduces the size of the large pool of young people searching for jobs (this effect is marginal), but through remittances from migrants in sending countries to their families. The size of this flow of capital, currently worth 281 billion dollars, is three times higher than that of official development aid. [9]9 — Ratha, D. K.; De, S.; Dervisevic, E.; Plaza, S.; Schuettler, K.; Shaw, W.; Yousefi, S. R. (2016). Migration and Remittances: Recent Developments and Outlook. SIDALC. However, the positive effect of remittances on development are offset by the negative effects of brain drain. Turning brain drain into a situation of brain circulation, whereby migrants temporarily move to more developed countries and return to their country of origin after several years, having gained additional schooling and experience, might help to overcome these negative effects. But taken together, net emigration from countries of the Global South will not solve their economic problems either.

This demographic imbalance will not disappear in the near future. Although aging is a prominent issue on the agenda for many countries, we are in the middle of an aging process that will continue in the coming decades. The proportion of the 65-plus population in the European Union will increase from its current 20% to 30% by 2050 and then remain at that high level. Similarly, although the proportion of young people in Africa is decreasing and currently stands at 50% in the 0-19 age bracket, in absolute terms the size of the young population will still increase, from the current 682 million to 973 million by 2050. It is only in the long run, well after 2050 for Africa and other poorer countries of the Global South, that they will have to deal with aging. For most of these countries the problem is how to become rich before their population ages. If ageing occurs before the means to deal with its costs are obtained, the burden of a large young population today may turn into the heavy burden of an aging population. But before that happens, the demographic imbalance between the Global South and the Global North will likely continue to stir global migration flows in the future.

Humanitarian crises and refugees

Throughout history, people have been forced to leave their homes because of war, persecution or natural disaster. Persons fleeing their country are covered by the Refugee Convention of 1951. This means that receiving states have the legal obligation to protect and grant them civil rights. According to UNHCR, there are currently 32 million officially recognised refugees, up from 12 million in 2000, and still rising fast. Persons fleeing from their home for the same reasons but not crossing a state border are called internally displaced persons (IDPs). The number officially recognised by the UNHCR is currently 67 million, a tenfold increase since 2000, and more than twice as large as the number of refugees.

These increasing numbers reflect growing instability across the world, but the origins of the refugees are concentrated in a few main conflict hotspots – Afghanistan, Venezuela, Syria, Ukraine and Sudan – and account for 71% of the total number of refugees worldwide. The main destinations of people fleeing from these countries are their neighbouring countries: almost 90% of Afghan refugees have been granted asylum in either Iran or Pakistan, 90% of Sudanese refugees have found shelter in Chad, South Sudan or Ethiopia, and more than 60% of Syrian refugees have fled to Turkey or Lebanon. Together with the large number of IDPs, this reflects the finding that most refugees are overwhelmingly given shelter in their regions of origin, which are typically low-income countries. Apart from armed conflicts, climate disasters¬ – in the form of droughts or flooding – will add to the growing flow of refugees and IDPs. They too, tend to find refuge in their region of origin.

There are many public misconceptions regarding refugees. A widespread opinion in Europe and the US is that refugees should not be hosted in their countries but in the region of origin. The reality is that the EU countries, together with the UK, North America and Australia/New Zealand, receive about a quarter of refugees worldwide, including Ukrainian refugees, for which Europe is the region of origin. Another misconception is equating migrants with refugees or asylum seekers. However, as the figures presented here show, the latter represent only 11% of the total number of migrants.

Current international developments are not exactly leading to a more stable world theatre. A political divide is emerging between two political blocks, led by the United States, on the one hand, and China and Russia, on the other. A new geopolitical dimension is being added to local conflicts, in which the opposing parties choose different sides in this global rivalry. The number of casualties from armed conflicts worldwide increased from 400,000 in the first decade of this century, to almost 1 million in the second decade, and in the period 2020-2023 another 80,000 were added to this figure. [10]10 — Herre, B.; Rodés-Guirao, L. (2023). “Our Data Explorers on Armed Conflict and War”. Published at Our World in Data. Available online. Although these events are very hard to predict, this situation is unlikely to improve in the near future, and the current stark increase in the number of refugees and IDPs will therefore continue for some time.

Migration policies

There is no universal theory that can include all aspects of migration. Migration also takes place from high- to low-income countries. Japan, with the oldest population on earth (about 30% of the population is currently over 65) has a very low immigration rate. So other factors play a large role in explaining the many exceptions to the rule. Policy is particularly relevant here. Supranational institutions, such as the EU, allow free movement across its internal borders. This has significantly increased internal migration within the EU: between 1990 and 2020 the number of migrants born in one of the EU-28 countries (including the UK) and living in another EU-28 country increased from 10.5 to 23 million. However, this number is much lower than the number of migrants born outside but living in the EU-28, which rose from 17 million in 1990 to 41 million in 2020.

While this increase from outside the EU countries is in line with global economic and demographic trends, it is at the same time a highly contested issue. In many countries of the Global North, there is strong opposition to immigration, and particularly to asylum seekers, based on the belief, often spread by social media, that they are dishonest and profiteering from the hospitality of the receiving countries. Despite the strong rhetoric, many politicians who officially support these ideas also realise that with a harsh anti-migration policy a country would be shooting itself in the foot, as Brexit, for instance, has shown. Therefore, anti-migration politics seemingly focus on the most vulnerable migrant groups – asylum seekers – while allowing labour migration to flow more freely. Italy and Hungary are clear examples here. As Hein de Haas remarks in his book How Migration Really Works, [11]11 — De Haas, H. (2023). How Migration Really Works: A Factful Guide to the Most Divisive Issue in Politics. Random House. if you want to get rid of migrants, destroy your economy.

Conclusions

The key drivers of global migration, namely, the economic and demographic divide and humanitarian crises, all point to a further increase in global migration in the coming years. The rich but aging societies of the Global North need workers to keep their economies growing, whereas the young but poor populations of the Global South need jobs to earn an income. Present policies and a widespread anti-migration sentiment in many countries of the Global North are at odds with these developments. It is in the interest of these countries to welcome migrants who can support the host societies, where a lot depends on the success of integration policies.

Humanitarian crises will add to this structural increase in migration flows in an unpredictable manner. In this regard, the most vulnerable migrant groups are refugees and IDPs, and the refugee or asylum crisis, as it is often called, is to a large extent a crisis of lack of will to properly deal with the problem. The current narrative needs to change to cope with it in the coming years.

• References

  1 —

  United Nations Department of Economic and Social Affairs (UN DESA), Population Division (2020). International Migrant Stock 2020.

  2 —

  Abel, G. J.; Sander, N. (2014). “Quantifying Global International Migration Flows”. Science, no. 343 (6178), pp. 1520-1522.

  3 —

  Massey, D. S.; Arango, J.; Hugo, G.; Kouaouci, A.; Pellegrino, A.; Taylor, J. E. (1993). “Theories of International Migration: A Review and Appraisal”. Population and Development Review, no. 19 (3), pp. 431-466. Available online.

  4 —

  United Nations Department of Economic and Social Affairs (UN DESA), Population Division (2024). World Population Prospects. The 2024 Revision. Available online.

  5 —

  See, for instance, De Haas, H. (2023). How Migration Really Works: A Factful Guide to the Most Divisive Issue in Politics. Random House.

  6 —

  Author’s own calculations based on the World Inequality Database. Available online.

  7 —

  Lutz, W.; Crespo Cuaresma, J.; Kebede, E.; Prskawetz, A. P.; Sanderson, W. C.; Striessnig, E. (2019). “Education Rather Than Age Structure Brings Demographic Dividend, Proc. Natl. Acad. Sci. USA, no. 116 (26), pp. 12798-12803. Available online.

  8 —

  United Nations Department of Economic and Social Affairs (UN DESA) (2000). Replacement Migration: Is It a Solution to Declining and Ageing Populations? Available online.

  9 —

  Ratha, D. K.; De, S.; Dervisevic, E.; Plaza, S.; Schuettler, K.; Shaw, W.; Yousefi, S. R. (2016). Migration and Remittances: Recent Developments and Outlook. SIDALC.

  10 —

  Herre, B.; Rodés-Guirao, L. (2023). “Our Data Explorers on Armed Conflict and War”. Published at Our World in Data. Available online.

  11 —

  De Haas, H. (2023). How Migration Really Works: A Factful Guide to the Most Divisive Issue in Politics. Random House.