Migration has always been part of human societies. Mobility and adaptation to distinct environments are trademarks of our evolutionary history. According to UN’s International Organization for Migration estimates[1], there are around a billion migrants around the world, 230 million of them living outside their birth countries (international migrants). Over 10% of the population in developed countries is foreign-born, against 1.6% at the world periphery. In absolute numbers, this accounts for 135 million international migrants living in developed countries and 95 million in undeveloped ones.

The rising inequalities between poor and rich countries during the 20^th century, the evolution in transport technologies and globalization suggest that international migration would be rapidly expanding. While that is true in absolute terms, the proportion of international migrants over total population is still low and has not risen significantly, from 2.9% to 3.2% between 1990 and 2013, according to UN data[2]. Migration costs and barriers (financial, informational, social and cultural), and restrictive entrance policies from states, which raise migration’s costs while diminishing its benefits, exert a negative pressure on migration flows. However, those human movements’ complexity and variety increase, and four large processes stand out among them: a migratory pressure from developing to developed countries (South-North migration); greater mobility of a global elite among developed countries, due to higher mobility encouraged by wealth and productive complexity (North-North migration); the mobility between developing countries (South-South); and, also, the rising number of refugees and their consolidation as a specific human group.

South-North migration is mostly caused by higher income opportunities and better life conditions offered by developed countries. The possibility to earn above subsistence, or near-subsistence, levels, in strong currencies, also allows migrants to send money to their family at their origin country, or accumulate to invest when returning. Studying and working abroad in a developed country tends to increase professional possibilities for those coming from the developing world when they return home, both for the qualification and status they provide. The number of migrants who took this route went from 40 to 74 million from 1990 to 2010, when it accounted for 35% of all migrants.

One can also perceive the expanding mobility of a global elite, mainly between developed countries. The recent globalization is focused on enhancing the mobility of capital and goods, not on the circulation of workers among national states. In spite of that, highly qualified students and professionals, and those with enough financial resources, face fewer restrictions and do present high mobility. North-North migrant’s volume shows this trend, with its stock going from 42 to 53 million between 1990 and 2010. Moreover, developed countries have 17% of the world’s population, but are origin to 31% of international migrants (80% of those living in another developed country). Although mainly a rich-country phenomenon, middle-income countries like China, India, Brazil and Mexico have some social and economic sectors embedded in those networks.

South-South migration until recently comprehended the largest share of migrants, but has been losing relative importance, going from 40% to 34% of the total international migrant population between 1990 and 2010[3]. Those are also the most difficult to categorize, as they involve a variety of determinants and features. One can perceive economic migration from poorer to middle-income countries, migrations motivated by specific productive sectors and niches; a series of circular and seasonal migrations; a “horizontal” move between neighboring countries; migration motivated by ethnical and religious issues, political and economic instability and civil or military conflicts, among others.

A fourth process to highlight is the expansion of the number of refugees. Urban centers, ever more populous, have become the focus of military conflict, and the rising power of weapons leads to growing mortality and destruction. In Africa and the Middle East, states divided in rival ethnic and religious groups are spaces of disputes whose goal, commonly, is to subjugate, expel or exterminate the adversaries, motivating forced migration. The Middle East, target of geopolitical dispute and external invasion in the last decades, houses the greater number of current conflicts and, consequently, refugees. According to UN estimates, there existed around 16.7 million international refugees in 2013 (7.2% of migrants) and 33 million internal refugees; those numbers have grown considerably for the last two years, given the deepening crisis in Iraq and Syria. Around 86% of refugees live in developed countries; 50% live in UN concentration camps, 40% are children[4]; most have little or no social and political rights. The low rates of return and asylum concession, combined with the growing number of displaced people, create a situation where around two thirds of refugees have been in this condition for more than five years.

Connected to all those trends, there has been unraveling an unprecedented structural transformation on the way human societies organize their territory: an urbanization process initiated in Western Europe around the 18^th century that determines most contemporary human movements from then on. In 2009, UN-Habitat estimated[5] that nowadays 3 million people migrate from rural to urban areas each week — most of them without leaving their country. Developed countries and most of Latin America already have high rates of urbanization, but in most of Asia and Africa this process is relatively recent, and occurs at high speed. From 1950 to 2013, urban population went from 30% to 54% of the total world population, and estimates suggest it will be near 70% in 2050. One in every eight urban inhabitants lives in one of the 28 cities whose populations lie above 10 million people. Among international migrants, concentration in large cities is even more impressive: according to 2015 UN’s report on international migration, around 20% of international migrants live in one of the 19 metropolises whose foreign population exceeds that of one million (nine cities in North America, three in Europe, three in the Middle East, two in Southeast Asia and two in Australia).

The nature of migratory processes has also been changing in shape and form. Temporary and circular migrations increase with the advance of transport technologies, even if most of humanity lacks resources to appropriate those. Internet and other communication technologies increase the migrants’ capacity to get information about their destination, enabling them to keep closer ties with their origin country. Advances in surveillance and control technologies might increase a state’s power to effect restrictive migration policies and make it harder for irregular migrants to cross borders. On the other hand, population ageing in developed countries might alleviate the pressure on restrictions as they need a younger workforce. In addition, global warming, rising seas, the deterioration of soils and rivers, environmental disasters, seismic and climatic extreme events, all may generate important human movements for the next decades, as disputes for scarce and valuable urban spaces push an increasing number of people to live in areas of risk.

The development of productive forces and the technological advances should keep increasing the volume and the complexity in human movements, but they also allow states to maintain or expand their capacity to limit them according to their interests. Broadening the dialogue and building an internationally coordinated policy to deal with migration become, in this context, essential to guarantee respect to basic rights and freedom of movement to a great part of the world’s population.

[1]  UNITED NATIONS (UN). International Migration Report 2013. New York, 2013. Retrieved from in Jan. 2016.

[2]  UNITED NATIONS (UN). International Migration Report 2013. New York, 2013.  Retrieved from in Jan. 2016.

[3]  UNITED NATIONS (UN). Migrants by origin and destination: the role of South-South migration. Population Facts, New York, n. 2012/3, June 2012. Retrieved from in Jan. 2016.

[4]  INTERNATIONAL ORGANIZATION FOR MIGRATION. Global Migration Trends: an overview. Geneva, 2014. Retrieved from . in Jan. 2016.

[5]  UNITED NATIONS HUMAN SETTLEMENTS PROGRAMME. State of the World’s Cities 2008/2009: harmonious cities. London; Sterling, VA: Earthscan, 2009. Retrieved from in Jan. 2016.