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Indicator Assessment
The world’s population increased from 2.5 billion in 1950 to around 7.3 billion in 2015, 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 9.7 billion by 2050, and rise further to 11.2 billion by 2100. However, if fertility and mortality rates stay at current levels (i.e. assuming the ‘no change’ projection variant), growth rates are projected to be substantially higher, with global population possibly rising to 10.2 billion by 2050 and 19.3 billion by 2100.
The 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 1.2 billion today to about 4.5 billion by 2100, under ‘medium fertility’ assumptions.
The total population of the EU-28 is projected to increase slightly from 505 million currently to 510 million by 2030, and then to decrease in the subsequent decades to some 465 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 19 % currently to 30 % by 2050 and further to 32 % by 2100, under ‘medium fertility’ assumptions.
Projected population change in European countries, 2015 to 2100
Note: The map shows the projected change in total population in the EEA and western Balkan countries, 2015 to 2100
The world's population has almost tripled over the last 60 years, rising from ca. 2.5 billion in 1950 to around 7.3 billion in 2015 (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 between 8.7 billion (‘low fertility’ projection variant) and 10.9 billion (‘constant fertility’ projection variant). Assuming the ‘medium fertility’ projection variant, global population is expected to increase to 9.7 billion by 2050.
The spread across the different UN projection variants increases further for the period 2050-2100, 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 7.3 billion by 2100, which is about its current size. At the other extreme, under the assumption of constant fertility rates (as estimated for the period 2010-2015) but increasing life expectancy (e.g. due to improved health care systems), global population could increase to as much as 26 billion by 2100. If both fertility rates and life expectancy remain constant between 2010 and 2015 (‘no change’ projection variant), global population could reach 19.3 billion by 2100. Assuming the ‘medium fertility’ projection variant — i.e. globally increasing life expectancy combined with increasing fertility rates in current low fertility regions but decreasing fertility rates in current very high fertility regions — global population is expected to increase to 11.2 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 that life expectancy will increase over 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 it 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 the assumption 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 and2015, rising from 1.4 billion to 4.4 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 about another billion to 5.3 billion by 2060, but to slightly decrease to 4.9 billion by 2100. Africa’s population has increased 5-fold from 1950 to 2015, rising from around 200 million to 1.2 billion, and is projected to grow substantially and continuously to 2.5 billion by 2050 and 4.4 billion by 2100 (Figure 2).
The population of the current EU-28 increased from 380 million in 1950 to 505 million in 2015 (Figure 3).
The ‘medium fertility’ projection variant assumes a relatively stable EU-28 population throughout the 21st century, with a slight increase to 510 million by 2030, and a decrease in subsequent decades to 465 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 greatest 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 will drop to 360 million by 2100, which would mean a loss of about 30 % of its current size. Only under ‘high fertility’ and ‘instant replacement’ assumptions, would the EU-28 population grow towards 2100 (to 680 million and 605 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 from 1950 to 2015, rising from 8.9 % to 19.2 % (Figure 4). Over the coming decades, the EU ageing trend is projected to continue. By 2050, the share of persons aged 65 years and older is projected to be between 27 % (‘high fertility' scenario) to 33 % (‘low fertility’ scenario), and might further increase to 41 % by 2100 under low fertility assumptions (Figure 4). Ageing populations are also projected to become a global phenomenon in the coming decades — for example, assuming the ‘medium fertility’ variant, the global share of persons aged 65 and older is projected to rise from 8.3 % currently to 16 % by 2050 and 23 % by 2100 (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 country by the United Kingdom (Figure 5). As the UK’s population increase is based, in part, upon substantial levels of immigration, it is an example of how migration might play a role in determining developments in population size across European countries over the coming decades. 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 EU-28 and EEA member countries shows that eastern European countries in particular, 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 large increases are projected for Ireland, Luxembourg, Norway, Sweden 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 is defined as the “de facto population in a country, area or region as of 1 July of the year indicated” (UN, 2015b). Population changes from one year to another are due to natural population change (the difference between the number of live births and deaths during a given time period) (Eurostat, 2015) and net migration (the number of immigrants minus the number of emigrants) (UN, 2015b) in a given country or region.
The figures presented in this indicator include population estimates for 1950-2015 and eight projection variants for 2015-2100. These projection variants have been developed by the United Nations Department of Economic and Social Affairs (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 projection variants as defined in the World Population Prospects: The 2015 Revision (UN, 2015a).
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 2010–2015 |
Normal |
Normal |
|
Instant replacement fertility |
Instant replacement as of 2015-2020 |
Normal |
Normal |
|
Constant mortality |
Medium |
Constant as of 2010–2015 |
Normal |
|
No change |
Constant as of 2010–2015 |
Constant as of 2010–2015 |
Normal |
|
Zero-migration |
Medium |
Normal |
Zero as of 2015–2020 |
Time horizon: 1950-2100
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 and Oceania.
References
Eurostat, 2015, 'Glossary: Natural population change'
UN, 2015a, 'World Population Prospects: The 2015 revision'
UN, 2015b, 'World Population Prospects: The 2015 Revision — Glossary of demographic terms'
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 ongoing 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 with 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.
The UN DESA World Population Prospects (WPPs) are produced every two years. The 2015 Revision, presented here, was published on 29 July 2015 (UN, 2015a). The dataset includes past estimates covering 1950–2015 and outlook data (projections) for 2015–2100.
Estimates based on historical data for 1950–2015
Past estimates for 233 countries and areas were produced employing the cohort-component method, using population counts from national censuses as benchmarks. The components of population change (fertility, mortality and international migration) were taken from national statistical sources (censuses, demographic surveys, registries of vital events, population registers and refugee statistics), or were estimated when only partial or poor-quality data were available.
Necessary adjustments were made for deficiencies in age reporting, under-enumeration, or under-reporting of vital events. This was the case for most countries in less developed regions, where the estimation of past trends is usually more complex. In numerous cases, therefore, consistency could only be achieved by making use of models in conjunction with methods of indirect estimation.
The key task was, therefore, to ensure that for each country, past trends of fertility, mortality and international migration are consistent with changes in the size of the population and its distribution by age and sex. The overall analytical approach used in the 2015 Revision consisted of four major steps: (i) data collection, evaluation and estimation to derive a trend line; (ii) further evaluation and adjustments in relation to geographical completeness and demographic plausibility; (iii) consistency checking and cross-validation of each population component against the other population components; and (iv) consistency checks across countries (UN, 2015c).
Projections for 2015-2100
The UN population projections are based on the cohort-component projection method, which provides a framework to account for the three demographic components of change – fertility, mortality and international migration.
Regarding the projection of total fertility, the 2015 Revision used the same probabilistic method as the 2012 Revision, with two amendments. The model takes into account the latest census data from newly available surveys, and employs an improved approach to project the age pattern of fertility consistently across all countries of the world. For details on the different fertility variants see below.
Mortality was projected by means of probabilistic methods for projecting life expectancy at birth. The approach is based on a Bayesian Hierarchical Model (BHM) and is similar to the one used in the 2012 Revision, modelling the mortality transition from high to low mortality (for details see ‘normal mortality’ below)
Data on international migration are recognised by the UN as often being sparse or incomplete. Therefore, several pieces of information were used as input for the projections, such as net international migration or its components (immigration and emigration) as recorded by countries, data on labour migration flows, estimates of undocumented or irregular migration and data on refugee movements (UN, 2015c).
Specific assumptions for projection variants
The following specific assumptions and combinations thereof have been used to generate the eight projection variants of the 2015 Revision (UN, 2015c, page number(s) for further details):
Recent (i.e. 2010 or later) population data from censuses or official estimates based on censuses and population registers were available only for 172 of the 233 countries or areas included in the analysis. For 54 countries, the most recent population data available were from 2000-2009. For the remaining seven countries, the year of the most recent data available ranged from 1975 in Somalia, to 1984 in the Democratic Republic of Congo and Eritrea and to 1998 in Pakistan. Thus, depending on the availability of the most recent information in a given country, estimates for 2010-2015 or for the year 2015 were, in many cases, based on a short-term forward projection from earlier time periods with available data.
Reliable historic time series of the three main components of population change (fertility, mortality and international migration) are ideally based on complete, sex-specific, annual time series of age-specific fertility rates, life tables and age-specific rates of net international migration from official statistics. However, in many cases, such information was either outdated or completely lacking. In those cases where information was lacking entirely, estimates were derived from other surveys, especially for countries lacking a civil registration system or one without sufficient coverage of all vital events (UN, 2015c).
No methodology references available.
Both past estimates (1950–2015) and outlook data (2015–2100) are associated with a number of uncertainties (UN, 2015c).
With regard to historical estimates, the absence or poor quality of demographic information, in particular in developing countries, and, as a consequence, the need to employ gap-filling methods to derive internally consistent estimates, is the most important source of uncertainty. Concerning information on fertility and child mortality, the percentage of countries or areas with lacking or outdated data was small. However, data on adult mortality were lacking for countries and areas totalling 16 % of the global population. Thus, a major weakness faced in producing the 2015 base-year estimates of the population by age and sex for each country was the lack of recent data on adult mortality.
Moreover, the UN acknowledges that even by combining the best available information sources on international migration (e.g. by the Office of the United Nations High Commissioner for Refugees), the production of comprehensive and consistent estimates of net migration remains a limiting factor to producing more accurate historical population estimates.
Concerning future demographic trends modelled for the 85-year period 2015-2100, the spread across the eight projection variants illustrates the uncertainty inherent in such probabilistic projections. The different projection variants also convey the sensitivity of the projections to changes in the underlying assumptions, such as changes in fertility.
The statistical modelling approach using the BHM also attempts to capture some of the uncertainty. For example, uncertainties in relation to the pace of future fertility decline (i.e. phase two of the fertility transition - for details see the ‘Methodology’ part above) is addressed by generating 600 000 double-logistic curves for all countries that have experienced a fertility decline. By systematically sampling one in ten of the 600 000 simulated trajectories produced by this process, the end result was 60 000 projected trajectories of total fertility for each country. The median of these 60 000 trajectories is used as the medium fertility variant projection.
Other uncertainties relate to temporal and geographic scale. As the time period increases so does the uncertainty inherent in the projections, meaning that, for example, the estimates for 2050 are more uncertain than those for 2020. Uncertainty also increases with geographical detail, and is higher at the individual country level than, for example, at continental level. Detailed information on the uncertainty bounds for different components at the country level is available on the website of the UN DESA Population Division.
References
UN, 2015c, World Population Prospects: The 2015 Revision — Methodology of the United Nations population estimates and projections, Working Paper No. ESA/P/WP.242, United Nations Department of Economic and Social Affairs (DESA), New York, US.
As described in the methodology for gap filling, there are challenges relating to the quality of individual country data so the main recorded dataset uncertainty is at the level of individual countries.
N/A
For references, please go to https://www.eea.europa.eu/data-and-maps/indicators/total-population-outlook-from-unstat-3/assessment-1 or scan the QR code.
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