The starting line of a long decline
Between the 2011 and 2021 Censuses, the Alentejo recorded the largest regional population drop in Portugal, with a 7.0% decrease across its entire territory, according to data released by Statistics Portugal (INE) in 2021. This sharp contraction is not a recent phenomenon, finding its roots in long-term dynamics that have profoundly transformed the local demographic landscape and systematically reduced the resident base in dozens of parishes in the deep interior.
A broader historical perspective shows that this demographic erosion has accumulated decades of continuous losses in various parts of the region. According to records from the Municipality of Ferreira do Alentejo published in 2020, the municipality lost 47.2% of its population between 1950 and 2011, approaching the critical threshold of half its inhabitants within a span of six decades. This movement of progressive emptying has primarily affected low-density parishes exclusively linked to extensive rainfed agriculture.
At the top of the most severe losses of the most recent decade, the municipality of Barrancos stood out in INE's 2021 Census by recording the largest population drop in the entire country, settling at a 21.6% decrease. Along the same lines of strong contraction, the municipality of Mértola recorded a population decrease of over 10% between 2011 and 2021, according to official data published by INE in 2022, deepening the geographical and social isolation of these borderland communities.
The invisible weight of aging
Population loss is not measured solely through negative net migration, but above all through the profound change in the age structure that conditions the future sustainability of local public services. In estimates released by Statistics Portugal (INE) in 2025, the aging index in the Alentejo region reached an alarming value of 222 elderly people for every 100 young people, a ratio well above the national average that highlights the accumulated generational imbalance.
The situation reaches extreme levels in specific municipalities in the northern interior of the region, where the base for youth renewal is practically exhausted. According to data from the Fundação Francisco Manuel dos Santos (PORDATA) for 2025, the municipality of Gavião recorded an aging index of 535.1 elderly people for every 100 young people, the highest value in the entire Alentejo territory and a clear indicator of local challenges in providing healthcare and home care support.
This imbalance is directly reflected in economic capacity and the maintenance of the active workforce in vulnerable geographical areas. According to the same PORDATA indicators from 2025, the demographic sustainability index in municipalities such as Nisa stood at 1.36 working-age people per elderly person, generating increased pressure on social security and local solidarity systems in an area marked by housing dispersion.
The long-term horizon mapped out by models
The long-term demographic projections prepared by Statistics Portugal (INE) in 2017 indicate that the Alentejo region could lose more than 230,000 inhabitants by 2080, compared to the baseline values recorded in 2015. This volume of loss is roughly equivalent to removing the entire current population of several district capitals in the region, irreversibly altering the territorial occupancy density and the viability of basic infrastructure networks.
The intensity of this decline was internationally highlighted by the Organisation for Economic Co-operation and Development (OCDE) in a case study dedicated to the Alentejo published in 2021, where the region was pointed out as one of those registering the fastest demographic decreases among the major international regions evaluated by the entity, surpassing the contraction average of other peripheral European zones.
At the most recent sub-regional level, the Fundação Francisco Manuel dos Santos (PORDATA) indicated in 2025 that the Alto Alentejo sub-region recorded the largest year-on-year population reduction in the country in 2024, with a negative variation of 0.49%. In parallel, population estimates based on administrative sources published by INE in 2026 show that the Baixo Alentejo had a global total of 125,767 inhabitants, highlighting the slowness in reversing this downward trend.
The fallacy of uniform desertification
The most obvious reading would point to a homogeneous and irreversible desertification of the entire Alentejo territory toward the total loss of half the population in the coming decades, foreseeing a scenario of absolute abandonment from one end of the region to the other. However, official data demonstrate a marked polarization, where coastal municipalities and areas with strong agricultural migration influxes grow, defying the absolute demographic collapse visible in interior municipalities.
The most evident example of this break with the general pattern of decline is found in the municipality of Odemira, which bucked the regional trend by recording population growth of 13.3% between 2011 and 2021, decisively driven by migration dynamics linked to intensive agricultural farming, according to definitive data from the 2021 Census published by INE.
Along the same line of divergence from the deep interior, the Alentejo Litoral sub-region recorded population growth of 0.82% in 2024, defying the drop felt in the remaining Alentejo sub-regions, according to statistical data consolidated by Fundação Francisco Manuel dos Santos (PORDATA) in 2025. This reality proves that decline does not affect the Alentejo as a single, undifferentiated block.
The risk factor in forest and brush areas
The intersection between demographic decline and environmental vulnerability reaches critical proportions in the areas most exposed to rural fires in the southern region. In high-risk rural fire zones located in the Baixo Alentejo, the aging index reached a national high of 560 elderly people for every 100 young people in 2026, according to analytical data released by Statistics Portugal (INE) in the same year.
This extreme concentration of an aging population in high-risk forest territories severely restricts the self-protection capacity of local communities, conditioning land clearing and immediate intervention in case of emergency. The age group between 30 and 34 years old, crucial for the operational and economic management of the territory, simultaneously recorded a 31.3% drop nationwide between the 2011 and 2021 Censuses, with a direct and profound impact on the human desertification of the Alentejo interior, according to INE in 2024.
For those who live daily in one of the 47 municipalities of the Alentejo, these numbers do not represent statistical abstractions, but rather the tangible reduction of social responses, the closure of local schools, and the drastic reconfiguration of community life. The future survival of each municipality no longer depends on regional averages, but is instead dictated by the ability to secure new waves of economic activity and attract stable demographic flows in the face of advancing aging.