Population growth

Past and projected human population on different continents. The vertical axis is logarithmic and its scale is millions of people.

Population growth is the change in a population over time, and can be quantified as the change in the number of individuals of any species in a population using "per unit time" for measurement. In biology, the term population growth is likely to refer to any known organism, but this article deals mostly with the application of the term to human populations in demography.

In demography, population growth is used informally for the more specific term population growth rate (see below), and is often used to refer specifically to the growth of the human population of the world.

Simple models of population growth include the Malthusian Growth Model and the logistic model.

Population growth rate

In demographics and ecology, Population growth rate (PGR) is the fractional rate at which the number of individuals in a population increases. Specifically, PGR ordinarily refers to the change in population over a unit time period, often expressed as a percentage of the number of individuals in the population at the beginning of that period. This can be written as the formula:

$\mathrm{Growth\ rate} = \frac{(\mathrm{population\ at\ end\ of\ period}\ -\ \mathrm{population\ at\ beginning\ of\ period})} {\mathrm{population\ at\ beginning\ of\ period}}$

(In the limit of a sufficiently small time period.)

The above formula can be expanded to: growth rate = crude birth rate - crude death rate + net immigration rate, or ∆P/P = (B/P) - (D/P) + (I/P) - (E/P), where P is the total population, B is the number of births, D is the number of deaths, I is the number of immigrants, and E is the number of emigrants.

This formula allows for the identification of the source of population growth, whether due to natural increase or an increase in the net immigration rate. Natural increase is an increase in the native-born population, stemming from either a higher birth rate, a lower death rate, or a combination of the two. Net immigration rate is the difference between the number of immigrants and the number of emigrants.

The most common way to express population growth is as a ratio, not as a rate. The change in population over a unit time period is expressed as a percentage of the population at the beginning of the time period. That is:

$\mathrm{Growth\ ratio} = \mathrm{Growth\ rate} \times 100%.$

A positive growth ratio (or rate) indicates that the population is increasing, while a negative growth ratio indicates the population is decreasing. A growth ratio of zero indicates that there were the same number of people at the two times -- net difference between births, deaths and migration is zero. However, a growth rate may be zero even when there are significant changes in the birth rates, death rates, immigration rates, and age distribution between the two times. ^[1] Equivalently, percent death rate = the average number of deaths in a year for every 100 people in the total population.

A related measure is the net reproduction rate. In the absence of migration, a net reproduction rate of more than one indicates that the population of women is increasing, while a net reproduction rate less than one (sub-replacement fertility) indicates that the population of women is decreasing.

Human population growth rate

Annual population growth rate in percent, as listed in the CIA World Factbook (2006 estimate).^[2]

Growth rate of world population (1950-2000)

Population of the world from 10,000 BCE to 2000 CE (logarithmic scale)

Globally, the growth rate of the human population has been steadily declining since peaking in 1962 and 1963 at 2.20% per annum. In 2009 the estimated annual growth rate was 1.10%.^[3] The last one hundred years have seen a rapid increase in population due to medical advances and massive increase in agricultural productivity^[4] made possible by the Green Revolution.^[5]^[6]^[7]

The actual annual growth in the number of humans fell from its peak of 88.0 million in 1989, to a low of 73.9 million in 2003, after which it rose again to 75.2 million in 2006. Since then, annual growth has declined. In 2009 the human population increased by 74.6 million, and it is projected to fall steadily to about 41 million per annum in 2050, at which time the population will have increased to about 9.2 billion.^[8] Each region of the globe has seen great reductions in growth rate in recent decades, though growth rates remain above 2% in some countries of the Middle East and Sub-Saharan Africa, and also in South Asia, Southeast Asia, and Latin America.^[9]

Some countries experience negative population growth, especially in Eastern Europe (mainly due to low fertility rates and emigration). In Southern Africa, growth is slowing due to the high number of HIV-related deaths. Some Western Europe countries might also encounter negative population growth.^[10] Japan's population began decreasing in 2005 ^[11]

Excessive growth and decline

Main articles: Overpopulation and population decline

Population exceeding the carrying capacity of an area or environment is called overpopulation. It may be caused by growth in population or by reduction in capacity. Spikes in human population can cause problems such as pollution and traffic congestion, these might be resolved or worsened by technological and economic changes. Conversely, such areas may be considered "underpopulated" if the population is not large enough to maintain an economic system (see population decline). Between these two extremes sits the notion of the optimum population.

References

External links

2008 Essays on Population Growth Blue Planet United - Population Press
World population growth and trends 1950-2050 US Census
UN University annual "State of the Future" report, including updates on Millennium Project goals including balancing global population growth & resources
BBC News - Birth rate 'harms poverty goals' - 08/12/06
Trend of growth rate with total global population
Visual representation of global population and other statistics
Rosling, Hans (25 January 2009). "What stops population growth?". Gapminder. http://www.gapminder.org/videos/what-stops-population-growth/. Retrieved 2009-07-06.

POPULATION

Philippines Table of Contents

Population Growth

The Philippine population in the early 1990s continued to grow at a rapid, although somewhat reduced rate from that which had prevailed in the preceding decades. In 1990 the Philippine population was more than 66 million, up from 48 million in 1980. This figure represents an annual growth rate of 2.5 percent, down from 2.6 percent in 1980 and from more than 3 percent in the 1960s. Even at the lower growth rate, the Philippine population will increase to an estimated 77 million by the year 2000 and will double every twenty-nine years into the next century. Moreover, in 1990 the population was still a youthful one, with 57 percent under the age of twenty. The birth rate in early 1991 was 29 per 1,000, and the death rate was 7 per 1,000. The infant mortality rate was 48 deaths per 1,000 live births. Population density increased from 160 per square kilometer in 1980 to 220 in 1990. The rapid population growth and the size of the younger population has required the Philippines to double the amount of housing, schools, and health facilities every twenty-nine years just to maintain a constant level.

Migration

There were two significant migration trends that affected population figures in the 1970s and the 1980s. First was a trend of migration from village to city, which put extra stress on urban areas. As of the early 1980s, thirty cities had 100,000 or more residents, up from twenty-one in 1970. Metro Manila's population was 5,924,563, up from 4,970,006 in 1975, marking an annual growth rate of 3.6 percent. This figure was far above the national average of 2.5 percent. Within Metro Manila, the city of Manila itself was growing more slowly, at a rate of only 1.9 percent per annum, but two other cities within this complex, Quezon City and Caloocan, were booming at rates of 4 percent and 3.5 percent, respectively.

A National Housing Authority report revealed that, in the early 1980s, one out of four Metro Manila residents was a squatter. This figure represented a 150 percent increase in a decade in the number of people living in shantytown communities, evidence of continuing, virtually uncontrolled, rural-urban migration. The city of Manila had more than 500,000 inhabitants and Quezon City had 371,000 inhabitants in such neighborhoods. Moreover, rural-urban migrants, responding to better employment opportunities in peripheral metropolitan cities such as Navotas, had boosted the percentage of squatters in that city's total population.

A second major migration pattern consisted of resettlement from the more densely to the less densely populated regions. As a result of a population-land ratio that declined from about one cultivated hectare per agricultural worker in the 1950s to about 0.5 hectare by the early 1980s, thousands of Filipinos had migrated to the agricultural frontier on Mindanao. According to the 1980 census, six of the twelve fastest growing provinces were in the western, northern, or southern Mindanao regions, and a seventh was the frontier province of Palawan. Sulu, South Cotabato, Misamis Oriental, Surigao del Norte, Agusan del Norte, and Agusan del Sur provinces all had annual population growth rates of 4 percent or more, a remarkable statistic given the uncertain law-and-order situation on Mindanao. Among the fastestgrowing cities in the late 1970s were General Santos (10 percent annual growth rate), Iligan (6.9), Cagayan de Oro (6.7), Cotabato (5.7), Zamboanga (5.4), Butuan (5.4), and Dipolog (5.1)--all on Mindanao.

By the early 1980s, the Mindanao frontier had ceased to offer a safety valve for land-hungry settlers. Hitherto peaceful provinces had become dangerous tinderboxes in which mounting numbers of Philippine army troops and New People's Army insurgents carried on a sporadic shooting war with each other and with bandits, "lost commands," millenarian religious groups, upland tribes, loggers, and Muslims. Population pressures also created an added obstacle to land reform. For years, there had been demands to restructure land tenure so that landlords with large holdings could be eliminated and peasants could become farm owners. In the past, land reform had been opposed by landlords. In the 1990s there simply was not enough land to enable a majority of the rural inhabitants to become landowners. International migration has offered better economic opportunities to a number of Filipinos without, however, reaching the point where it would relieve population pressure. Since the liberalization of United States immigration laws in 1965, the number of people in the United States having Filipino ancestry had grown substantially to 1,406,770 according to the 1990 United States census. In the fiscal year ending September 30, 1990, the United States Embassy in Manila issued 45,189 immigrant and 85,128 temporary visas, the largest number up to that time.

In addition to permanent residents, in the late 1980s and early 1990s, more than half a million temporary migrants went abroad to work but maintained a Philippine residence. This number included contract workers in the Middle East and domestic servants in Hong Kong and Singapore, as well as nurses and physicians who went to the United States for training and work experience, a fair proportion of whom managed to become permanent residents. The remittances sent back to the Philippines by migrants have been a substantial source of foreign exchange.

Population Control

Popcom was the government agency with primary responsibility for controlling population growth. In 1985 Popcom set a target for reducing the growth rate to 1 percent by 2000. To reach that goal in the 1990s, Popcom recommended that families have a maximum of two children, that they space the birth of children at three-year intervals, and that women delay marriage to age twenty-three and men to age twenty-five.

During the Marcos regime (1965-86), there was a rather uneasy accommodation between the Catholic hierarchy and the government population control program. Bishops served on Popcom, and the rhythm method was included by clinics as a birth-control method about which they could give information. A few Catholic priests, notably Frank Lynch, even called for energetic support of population limitation.

The fall of Marcos coincided with a general rise of skepticism about the relation between population growth and economic development. It became common to state that exploitation, rather than population pressure, was the cause of poverty. The bishops withdrew from the Popcom board, opposed an effort to reduce the number of children counted as dependents for tax purposes, secured the removal of the population-planning clause from the draft of the Constitution, and attempted to end government population programs. Attacks on the government population program were defeated, and efforts to popularize family planning, along with the provision of contraceptive materials, continued. In the early 1990s, however, the program generally lacked the firm government support needed to make it effective.

Ethnicity, Regionalism, and Language

For more recent population estimates, see Facts about the Philippines.