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Indicator Assessment
The world’s population increased from 2.5 billion in 1950 to around 7 billion in 2010, and is expected to continue to rise until 2050/2100 under most UN projection variants. Assuming the ‘medium fertility’ projection variant, global population might increase to 9.6 billion by 2050, rising to 10.9 billion by 2100. However, if fertility and mortality rates stay at current levels (i.e. assuming the ‘no change’ projection variant), growth rates would be substantially higher, and the global population could rise to 10.2 billion by 2050 and 19.9 billion by 2100.
Expected global population growth is projected to be largely driven by increases in Asia and particularly in Africa. While the Asian population is expected to peak by 2050, Africa’s population is projected to grow strongly and continuously, from about 1 billion today to more than 4 billion by 2100, under ‘medium fertility’ assumptions.
The total population of the 28 EU Member States is projected to slightly increase from the current figure of 505 million to 520 million by 2030, and then to decrease in the subsequent decades to some 475 million by 2100, under ‘medium fertility’ assumptions. The age structure is projected to change substantially, with an increase of the share of people aged 65 years or older from the current figure of 17% to over 30% by 2050, under ‘medium fertility’ assumptions.
The world population has almost tripled over the last 60 years, rising from circa 2.5 billion in 1950 to around 7 billion in 2010 (Figure 1).
As shown in Figure 1, there is significant variation across the different UN projection variants as to how global population might develop over the coming decades. By 2050, global population is projected to be in a range between 8.3 billion (‘low fertility’ projection variant) and 11.1 billion (‘constant fertility’ projection variant). Assuming the ‘medium fertility’ projection variant, global population is expected to increase to 9.6 billion by 2050.
The spread across the different UN projection variants increases further for the period 2050 to 2100, reflecting the increasing uncertainties inherent in such long term projections. According to the ‘low fertility’ projection variant, global population might peak around 2050 and decrease to 6.8 billion by 2100. At the other extreme, under the assumption of constant fertility rates (as of 2005 to 2010) but increasing life expectancy (e.g. due to improved health care systems), global population could increase to as much as 28.6 billion by 2100. If both fertility rates and life expectancy remained constant as of 2005 to 2010 (‘no change’ projection variant), the global population could reach 19.9 billion by 2100. Assuming the ‘medium fertility’ projection variant, that is globally increasing life expectancy combined with increasing fertility rates in currently low fertility regions but decreasing fertility rates in currently very high fertility regions, global population is expected to increase to 10.9 billion by 2100 (Figure 1).
The huge spread across the UN projection variants towards the end of the 21st century also illustrates the effects of alternative assumptions related to fertility and mortality. For example, the considerably higher number for the ‘constant fertility’ compared to the ‘no change’ projection variant is due to the assumption of life expectancy increasing with time in the ‘constant fertility’ projection variant. Moreover, the lower values of the ‘high fertility’ projection variant in comparison with the ‘constant fertility’ and ‘no change’ projection variants illustrate that the ‘high fertility’ projection variant actually assumes a considerable reduction in fertility rates in many countries, compared to current levels. The assumption of the medium variant, therefore, is that fertility rates will experience a stronger drop, compared to what is assumed for the ‘high fertility’ projection variant.
A more detailed analysis of the ‘medium fertility’ scenario by world regions reveals that the projected increase in global population is largely driven by increases in Asia and Africa. The Asian population tripled between 1950 and 2010, rising from 1.4 billion to 4.2 billion, and Asia is projected to remain the most populous world region throughout the 21st century (Figure 2). Its total population is projected to increase by another billion to 5.2 billion by 2050, but to slightly decrease to 4.7 billion by 2100. Africa’s population increased five-fold between 1950 and 2010, rising from around 200 million to 1 billion, and it is projected to substantially and continuously grow to 2.4 billion and 4.2 billion by 2050 and 2100, respectively (Figure 2). Details on the historical development and future projections of Europe’s population are given in the specific assessment of this indicator.
The population of the current 28 EU member countries increased from 380 million in 1950 to 505 million in 2010 (Figure 3).
The ‘medium fertility’ projection variant assumes a relatively stable EU-28 population throughout the 21st century, with a slight increase to 520 million by 2030, and then a decrease in the subsequent decades to 475 million by 2100 (Figure 3). Other UN projection variants assume stronger changes in total EU population over time and most of them predict a considerable population decline. The strongest declines occur under ‘low fertility’, and, particularly, under ‘no change’ assumptions. If fertility rates, life expectancy and migration rates stay at current levels, the EU-28 population would drop to 270 million by 2100, which is almost half of its current size. Only under ‘high fertility’ and ‘instant replacement’ assumptions, the EU-28 population would grow towards 2100 (to 725 million and 620 million, respectively, Figure 3).
Strongly linked to the projected trend of a decreasing EU population is the growing share of older individuals. The share of persons aged 65 years and older of the total EU population doubled between 1950 and 2010, rising from 8.8% to 17.5% (Figure 4). Over the coming decades, the EU ageing trend is projected to continue. By 2050, the share of persons 65 years and older is projected to be in the range between 26% (‘high fertility' scenario) to 33% (‘low fertility’ scenario), and might further increase to over 40% by 2100 under low fertility assumptions (Figure 4). Ageing populations are also projected to become a global phenomenon in the next decades – for example assuming the ‘medium fertility’ variant, the global share of persons aged 65 and older is projected to rise from the figure of current 8% to 16% and 22% by 2050 and 2100, respectively (Figure 4).
Population trends across EU member countries are more complex, with the population of some countries projected to decrease significantly, while others are projected to increase between now and 2100. Thus, the national level assessment of this indicator is limited to exploring some of the most striking trends according to the ‘medium variant’ scenario. For example, by around 2050 Germany is projected to be replaced as the most populous EU Member State by either France or the United Kingdom (Figure 5). As the UK’s population increase is predicated, in part, upon substantial levels of immigration, trends in migration might play a role in determining whether France or the UK will be Europe’s largest. Other currently populous EU countries, such as Romania, Poland and Italy, are projected to experience a continuous and significant drop in population (Figure 5).
A comparison of changes in total population from 2010 to 2100 across the EU28 and EEA member countries shows that particularly eastern European countries, but also countries such as Germany or Portugal, are projected to be affected by large-scale population decreases (see Figure 6). In contrast, the population size of many northern and western European countries is projected to rise. Particularly strong increases are projected for Ireland, Sweden, Norway and Switzerland, in part driven by assumptions about immigration and increased life expectancy.
Another assessment of EU population trends has been published recently by the European Commission (EC, 2014).
References
EC, 2014, The 2015 ageing report — Underlying assumptions and projection methodologies, European Economy, 8/2014, European Commission, Brussels.
Population includes all residents regardless of legal status and citizenship.
Population change is defined as the “population increment over a period, that is, the difference between the population at the end of the period and that at the beginning of the period. It refers to five-year periods running from 1 July to 30 June of the initial and final years” (UN, 2013c). Within this indicator this includes natural population change (the difference between the number of live births and deaths during a given time period) (Eurostat, 2015) and net migration (the difference between the number of persons entering and leaving a country during a given period) (UN, 2013c).
The figures presented in this indicator include historical data and eight projection variants. These projection variants have been developed by UN DESA on the basis of varying assumptions related to fertility rates, mortality rates and international migration (for details see the Methodology section). The table below summarises the eight projections variants as defined in the World Population Prospects: The 2012 Revision(UN, 2013d).
Assumptions
|
Projection variant |
Fertility |
Mortality |
International migration |
|
Low fertility |
Low |
Normal |
Normal |
|
Medium fertility |
Medium |
Normal |
Normal |
|
High fertility |
High |
Normal |
Normal |
|
Constant fertility |
Constant as of 2005 – 2010 |
Normal |
Normal |
|
Instant replacement fertility |
Instant replacement as of 2010 - 2015 |
Normal |
Normal |
|
Constant mortality |
Medium |
Constant as of 2005 – 2010 |
Normal |
|
No change |
Constant as of 2005 – 2010 |
Constant as of 2005 – 2010 |
Normal |
|
Zero-migration |
Medium |
Normal |
Zero as of 2010 – 2015 |
Time horizon: 1950 to 2100
Geographical coverage: global, with specific attention to world regions and Europe. World regions are specified as defined by the United Nations Population Division Department of Economic and Social Affairs: Asia; Africa; Europe; Latin America and the Caribbean; Northern America; Oceania.
References
Eurostat, 2015, 'Glossary: Natural population change'
UN, 2013c, 'World Population Prospects: The 2012 Revision — Glossary of demographic terms'
UN, 2013d, 'World Population Prospects: The 2012 Revision — Highlights and advance tables', Working Paper No. ESA/P/WP.228, United Nations Department of Economic and Social Affairs (UN DESA), New York, US.
Number of people; percentage of people
Global policies
Although population is not subject to direct international policy it is recognised that population growth is central to many policy issues that the international community seeks to address. International organisations have put in place policies, programmes and funding to provide greater awareness and choice about birth control and demographic change. Examples include the United Nations Population Fund (UNFPA) which aims to “[deliver] a world where every pregnancy is wanted, every birth is safe, and every young person's potential is fulfilled” (UNFPA, 2015).
European Policies
There are no EU policies directly regulating Europe’s population size and structure. There are, however, a number of relevant initiatives. For example, in light of the on-going demographic changes in Europe (such as an ageing population, low fertility rates, changing family structures and migration) the European Commission issued a Communication "The demographic future of Europe – From challenge to opportunity" (COM(2006) 571 - final), which identified five key policy responses to manage demographic change
This strategy was renewed in 2009 with a new Communication “dealing with the impact of an ageing population in the EU” (COM(2009) 180 final). Aspects of this were included in Europe 2020, the European Commission’s growth strategy (COM(2010) 2020 final). One example of the Europe 2020 umbrella activities aimed at addressing European demographic trends is the Ambient Assisted Living Joint Programme (AAL JP), intended to support industry in providing services and products for an ageing population (EC, 2013).
Furthermore, the European Demography Forum, held by the European Commission every two years since 2006, provides policymakers, stakeholders and experts opportunities for knowledge sharing and discussion around demographic change.
In 2014 the European Commission issued a five point-plan on immigration including measures to secure Europe’s borders and to control and facilitate asylum and legal migration (EC, 2014). It recognises the need to develop a common legal migration policy to meet the increasing demand for skills and talents likely to arise as a result of the forecast demographic trends in the EU by 2060.
At the national and European regional level, additional initiatives and policies exist to address the specific demographic challenges.
There are no global, pan-European or EU objectives and targets relating to population.
Methodology for indicator calculation (i.e. generating projections until 2100)
The United Nations World Population Prospects (WPPs) are produced every two years. The 2012 version, presented here, was published in 2013 (UN, 2013).
The data set includes recorded (historical) data covering the period 1950–2010 and Outlook data (projections) for the period 2010–2100. The creation of both aspects of the data involves numerous methods and assumptions.
Since the 2010 revision the Population Division has developed further the methodology for producing probabilistic projections for all countries and areas of the world. In the 2010 Revision this was limited to fertility but the 2012 Revision incorporates, for the first time, probabilistic projections of mortality (UN, 2014).
Historical data
Past estimates of demographic variables are taken either directly from national statistical offices, or estimated by staff within the United Nations on the basis of the best available national or international estimates at the time. These population estimates are based on the most recently available data sources.
The five main recorded data sources (Heilig et al., 2012) are:
In some cases, it is deemed necessary to adjust the original data if there are identified deficiencies in age reporting, under-enumeration, or under-reporting. Adjustments are also made to take account of international migration flows (UN, 2014). These adjustments are made as more data become available, supported by expert review and assessment.
Projection variants
Predicting the structure and trajectory of future populations is based primarily on an understanding of the extant population and the fertility rate.
The extant population is based on the data sources set out previously.
Fertility rate calculations are based on four sources: vital registers (which report the number of births and age of the mother); surveys (of countries without vital registers); census; and adjustments (revised historical data).
Other key factors that are used to predict future populations are mortality and migration. For these factors the 2012 revision includes a new probabilistic method, which includes two separate steps: understanding progress made in female life expectancy at birth, and the gap between female and male life expectancy at birth.
As with the fertility models the results of this approach produce country-specific projections of life expectancy at birth that are fully reproducible and take into account past empirical trends. For some countries, those with exceptional changes in mortality, expert judgement is applied to the models to sense-check the results.
Data on international migration is recognised by the United Nations as being inadequate in the majority of countries. In these instances international migration is calculated, in part, on the basis of the difference between the actual recorded population change and the independent estimates of natural increase (i.e. a calculation of population change based on estimates of fertility and mortality).
Assumptions for projection variants
The following assumptions and combinations thereof have been used to generate the eight projection variants of the 2012 revision of the WPPs (UN, 2013d, with relevant page):
Past population trends are based on estimates for 233 countries and areas. Approximately half of those countries or areas do not report official demographic statistics with the detail necessary for the preparation of cohort-component population projections. The United Nations Population Division undertakes its estimation work in order to fill those gaps.
One way this is achieved is via major survey programs, such as the Demographic and Health Surveys or the Multiple-Indicator Cluster Surveys (which are a series of United Nations supported house-hold surveys) (UNICEF, 2013). These are used to generate some of the data that are not currently provided by official statistics.
The analysis carried out by the United Nations Population Division takes into account the data gaps and seeks to establish past population trends by resolving the inconsistencies affecting the basic data. This is achieved by grouping and comparing relevant countries and then extrapolating trends.
Identified uncertainty in the United Nation’s forecasts includes changes to future fertility rates, in particular second generation fertility (i.e. the fertility of current mothers’ children), child mortality, life expectancy and migration.
The forecasts use a Bayesian Hierarchical Model (BHM), which produces country-specific distributions for these uncertainties. These distributions are informed by the countries’ historical trends and the observed variability in historical trends for all countries. This means that within the model countries are grouped into different categories based on historical mortality and fertility trends. For example, for countries that currently already have a high life expectancy, smaller increases in life expectancy are predicted than for countries with currently comparatively low life expectancy (UN, 2014) (p.28). Likewise, countries with high levels of HIV/AIDS use slightly different models to account for the impact of this disease (UN, 2014) (p.35).
Historical trends are also used to model fertility trajectories over time, using three differing categories: high; medium; and low. These categories are based on historical evidence that suggests there is a transition over time as countries move from high, to low fertility and that it is possible to forecast fertility using historical data and trends. However, this approach is linked to uncertainties, in particular with respect to the development of fertility after the low fertility phase.
The United Nations recognise that migration is the most challenging feature to predict. In estimating migration the United Nations takes into account four pieces of information: (1) net international migration as recorded by countries; (2) data on labour migration flows; (3) estimates of undocumented/irregular migration; (4) and data on refugee movements in recent periods.
Most migration forecasts are based on the assumption that recent levels, if stable, would continue up to 2050. The countries are asked to provide expert views on international migration as well as estimates of undocumented and irregular migration flows affecting a country. It is also assumed that refugees return to their country of origin within five to ten years. Where a country has experienced both international migration and refugee movements, the two processes are combined to predict overall net migration.
Other uncertainties relate to temporal and geographic scale. As the time period increases so does the uncertainty inherent to the projections, meaning that, for example, the estimates for 2050 are more uncertain than those for 2020. There is also greater uncertainty at the scale of individual countries, compared to the aggregated regional and global projections.
References
UN, 2014, World Population Prospects: The 2012 Revision — Methodology of the United Nations population estimates and projections, Working Paper No. ESA/P/WP.235, United Nations Department of Economic and Social Affairs (UN DESA), New York, US.
As described in the methodology for gap filling there are challenges relating to the quality of individual countries’ data so the main recorded data set uncertainty is at the level of individual countries.
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For references, please go to https://www.eea.europa.eu/data-and-maps/indicators/total-population-outlook-from-unstat-2/assessment or scan the QR code.
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