MADRID — While some media and political discourses describe migration as a threat or an “avalanche,” data show the opposite: Spain is not experiencing an invasion, but a relationship of functional interdependence with the countries of the Global South. In other words, what is portrayed as a problem is, in reality, a structural need. The country needs a migrant population to sustain its demographic pyramid, its economy and its welfare system.
This migratory symbiosis is not a metaphor. It is a demographic reality. Since 1950, the world’s population has tripled. In regions such as sub-Saharan Africa and South Asia, growth is steady and sustained, putting pressure on resources, employment and social welfare systems. On the other hand, Europe and North America are facing the opposite phenomenon: population aging, low fertility rates and a gradually shrinking working population.
In the case of Spain, the contrast is clear. The fertility rate has been below 1.3 children per woman for years, far from the generational replacement threshold (2.1). Without constant migratory flows, Spain would lose millions of inhabitants in the coming decades, with direct effects on the tax system, pensions and employment. According to Spain’s National Statistics Institute (INE) and United Nations projections, if the current fertility rate is maintained without migration, the population could fall to 30 million in 2100, compared to the current 47 million.
In all these scenarios, we must bear in mind that babies born today would not start contributing to social security until 2045. In other words, aiming for a fertility rate of three children per woman would mean an additional economic burden on the welfare state for at least two decades, before these new generations could begin to sustain the system.
Neither birth rates are enough, nor is migration excessive
Given this outlook, can birth rates alone compensate for the demographic deficit? The answer is no. We have modeled three pro-birth policy scenarios, and all of them show structural limitations.
In the best-case scenario — with public policies sustained for 20 years — there would be no real impact before 2045. In more intensive scenarios (such as increasing to three or four children per woman in a legislative term), the results are ineffective, fiscally unsustainable and socially unfeasible. A structural problem cannot be compensated for with short-term measures or pressure on women’s bodies.
On the other hand, migration does have immediate effects. The arrival of young people of working age has helped to balance the ratio between contributors and retirees in recent decades. One study estimates that without migration, the demographic Sustainability Index— which measures how many people of working age there are for every person over 65 —would have been 30% lower, further exacerbating the pressure on the pension system.
Denying this reality for ideological reasons does not change the facts: It only prevents us from managing it realistically, with planning and fairness.
This means that the pressure on the pension system would have been much greater with fewer workers supporting it. Far from being a threat, migration has helped maintain the balance between contributors and retirees, delaying a collapse that would otherwise already be underway.
But migration does not only serve an economic function. Human mobility plays a redistributive role at the global level: It relocates the working population from regions with excessive demographic pressure to others with labor shortages and aging populations.
This interdependent relationship — albeit unequal — allows essential sectors such as care, agriculture, and hospitality to stay afloat. Denying this reality for ideological reasons does not change the facts: it only prevents us from managing it realistically, with planning and fairness.
Neither miracle nor threat
At the same time, aging poses additional challenges. Fewer workers means not only fewer contributions but also more healthcare spending, more dependency and more elderly people living on their own. In Spain, life expectancy has increased, and the feminization of old age introduces new inequalities: Many older women do not have their own pensions or depend on increasingly fragile family networks.
Projections show that without a consistent immigration policy, the Spanish welfare system will face unsustainable pressure. Discourses that reject immigration appeal to the myth of national self-sufficiency, but that model has never actually existed. Since the 2000s, Spanish growth has been directly linked to the work and contributions of millions of migrants.
Canada and Germany already implement active policies to attract and retain skilled and unskilled foreign workers.
This does not mean that migration is a magic solution. It also requires planning, integration, and rights. But it is an essential component of any realistic demographic strategy. In fact, countries such as Canada and Germany already implement active policies to attract and retain skilled and unskilled foreign workers. Spain, however, remains trapped in a narrative of emergency, insecurity and control.
That is why we must stop seeing Spain merely as a gateway for migration to Europe and start to understand its position as a strategic opportunity: to attract talent, address imbalances, and rejuvenate the social fabric. Remaining anchored in fear and emotional misinformation not only harms migrants but also deprives the country of an essential tool for its sustainability.
The migratory symbiosis between North and South is a reality of the 21st century. Denying it does not eliminate the problem, it only prevents effective solutions from being found.