Demographic features of the population of Portugal include population density, ethnicity, education level, health of the populace, economic status, religious affiliations and other aspects of the population.
In demography, demographic transition is a phenomenon and theory in the social sciences referring to the historical shift from high birth rates and high death rates to low birth rates and low death rates as societies attain more technology, education, and economic development. The demographic transition has occurred in most of the world over the past two centuries, bringing the unprecedented population growth of the post-Malthusian period, then reducing birth rates and population growth significantly in all regions of the world. The demographic transition strengthens economic growth process through three changes: a reduced dilution of capital and land stock, an increased investment in human capital, and an increased size of the labour force relative to the total population and changed age population distribution. Although this shift has occurred in many industrialized countries, the theory and model are frequently imprecise when applied to individual countries due to specific social, political, and economic factors affecting particular populations.
Sub-replacement fertility is a total fertility rate (TFR) that leads to each new generation being less populous than the older, previous one in a given area. The United Nations Population Division defines sub-replacement fertility as any rate below approximately 2.1 children born per woman of childbearing age, but the threshold can be as high as 3.4 in some developing countries because of higher mortality rates. Taken globally, the total fertility rate at replacement was 2.33 children per woman in 2003. This can be "translated" as 2 children per woman to replace the parents, plus a "third of a child" to make up for the higher probability of males born and mortality prior to the end of a person's fertile life. In 2020, the global average fertility rate was around 2.4 children born per woman.
Population decline, also known as depopulation, is a reduction in a human population size. Throughout history, Earth's total human population has continued to grow; however, current projections suggest that this long-term trend of steady population growth may be coming to an end.
Population ageing is an increasing median age in a population because of declining fertility rates and rising life expectancy. Most countries have rising life expectancy and an ageing population, trends that emerged first in developed countries but are now seen in virtually all developing countries. In most developed countries, the phenomenon of population aging began to gradually emerge in the late 19th century. The aging of the world population occurred in the late 20th century, with the proportion of people aged 65 and above accounting for 6% of the total population. This reflects the overall decline in the world's fertility rate at that time. That is the case for every country in the world except the 18 countries designated as "demographic outliers" by the United Nations. The aged population is currently at its highest level in human history. The UN predicts the rate of population ageing in the 21st century will exceed that of the previous century. The number of people aged 60 years and over has tripled since 1950 and reached 600 million in 2000 and surpassed 700 million in 2006. It is projected that the combined senior and geriatric population will reach 2.1 billion by 2050. Countries vary significantly in terms of the degree and pace of ageing, and the UN expects populations that began ageing later will have less time to adapt to its implications.
A population pyramid or "age-sex pyramid" is a graphical illustration of the distribution of a population by age groups and sex; it typically takes the shape of a pyramid when the population is growing. Males are usually shown on the left and females on the right, and they may be measured in absolute numbers or as a percentage of the total population. The pyramid can be used to visualize the age of a particular population. It is also used in ecology to determine the overall age distribution of a population; an indication of the reproductive capabilities and likelihood of the continuation of a species. Number of people per unit area of land is called population density.
The net migration rate is the difference between the number of immigrants and the number of emigrants divided by the population. When the number of immigrants is larger than the number of emigrants, a positive net migration rate occurs. A positive net migration rate indicates that there are more people entering than leaving an area. When more emigrate from a country, the result is a negative net migration rate, meaning that more people are leaving than entering the area. When there is an equal number of immigrants and emigrants, the net migration rate is balanced.
The Demographic Window is defined to be that period of time in a nation's demographic evolution when the proportion of population of working age group is particularly prominent. This occurs when the demographic architecture of a population becomes younger and the percentage of people able to work reaches its height. Typically, the demographic window of opportunity lasts for 30–40 years depending upon the country. Because of the mechanical link between fertility levels and age structures, the timing and duration of this period is closely associated to those of fertility decline: when birth rates fall, the age pyramid first shrinks with gradually lower proportions of young population and the dependency ratio decreases as is happening in various parts of East Asia over several decades. After a few decades, low fertility however causes the population to get older and the growing proportion of elderly people inflates again the dependency ratio as is observed in present-day Europe.
Demographic dividend, as defined by the United Nations Population Fund (UNFPA), is "the economic growth potential that can result from shifts in a population’s age structure, mainly when the share of the working-age population is larger than the non-working-age share of the population ". In other words, it is "a boost in economic productivity that occurs when there are growing numbers of people in the workforce relative to the number of dependents". UNFPA stated that "a country with both increasing numbers of young people and declining fertility has the potential to reap a demographic dividend."
The ageing of Europe, also known as the greying of Europe, is a demographic phenomenon in Europe characterised by a decrease in fertility, a decrease in mortality rate, and a higher life expectancy among European populations. Low birth rates and higher life expectancy contribute to the transformation of Europe's population pyramid shape. The most significant change is the transition towards a much older population structure, resulting in a decrease in the proportion of the working age while the number of the retired population increases. The total number of the older population is projected to increase greatly within the coming decades, with rising proportions of the post-war baby-boom generations reaching retirement. This will cause a high burden on the working age population as they provide for the increasing number of the older population.
Japan has the highest proportion of elderly citizens of any country in the world. 2014 estimates showed that about 38% of the Japanese population was above the age of 60, and 25.9% was above the age of 65, a figure that increased to 29.1% by 2022. By 2050, an estimated one-third of the population in Japan is expected to be 65 and older. Population aging in Japan preceded similar trends in other countries, such as South Korea and China.
In demography, replacement migration is a theory of migration needed for a region to achieve a particular objective. Generally, studies using this concept have as an objective to avoid the decline of total population and the decline of the working-age population.
Political demography is the study of the relationship between politics and population change. Population change is driven by classic demographic mechanisms – birth, death, age structure, and migration.
Fiscal sustainability, or public finance sustainability, is the ability of a government to sustain its current spending, tax and other policies in the long run without threatening government solvency or defaulting on some of its liabilities or promised expenditures. There is no consensus among economists on a precise operational definition for fiscal sustainability, rather different studies use their own, often similar, definitions. However, the European Commission defines public finance sustainability as: the ability of a government to sustain its current spending, tax and other policies in the long run without threatening the government's solvency or without defaulting on some of the government's liabilities or promised expenditures. Many countries and research institutes have published reports which assess the sustainability of fiscal policies based on long-run projections of country's public finances. These assessments attempt to determine whether an adjustment to current fiscal policies that is required to reconcile projected revenues with projected expenditures. The size of the required adjustment is given with measures such as the Fiscal gap. In empirical works, weak and strong fiscal sustainability are distinguished. Differences are related to both econometric techniques used for examination and variables involved.
China's population is aging faster than almost all other countries in modern history. In 2050, the proportion of Chinese over retirement age will become 39 percent of the total population according to projections. China is rapidly aging at an earlier stage of its development than other countries. Current demographic trends could hinder economic growth and create challenging social issues in China.
Population decline has many potential effects on individual and national economy. The single best gauge of economic success is growth in GDP per capita, not GDP. GDP per capita is an approximate indicator of average living standards, for individual prosperity. Therefore, whether population decline has a positive or negative economic impact on a country's citizens depends on the rate of growth of GDP per capita, or alternatively, GDP growth relative to the rate of decline in the population.
In demographic terms, aging refers to an increase in the proportion of senior citizens to the total population. The term "senior citizen" encompasses those aged 65 or older. In 2045, South Korea is projected to become the world's most aged population, surpassing Japan. Senior citizens will reach 46.5 percent of the population in 2067, outnumbering the working age population.
The societal effects of negligible senescence considers a scenario where negligible senescence is achieved on a societal wide level in humans. There is much controversy about the realistic timeline of such a scenario. The predictions vary in time starting from 2037 till later than the 21st century. The effects of negligible senescence has a profound impact on economy, climate, demographics and impacts social structures. The baseline scenario ceteris paribus of negligible senescence is more population growth while a larger healthier labor force would spur economic growth.
In recent decades, the fertility rate of the United States has declined below replacement level, prompting projections of an aging population and workforce, as is already happening elsewhere in the developed world and some developing countries. The decline has been most noticeable since after the Great Recession of the late 2000s. Nevertheless, the rate of aging in the United States remains slower than that seen in many other countries, including some developing ones, giving the nation a significant competitive advantage. Unintentional pregnancies have become less common; in particular, teenage pregnancies have dropped to record lows.
