A Guide To Population Growth And Density
J Gen Microbiol. Aug; Kinetics of bacterial growth: relationship between population density and specific growth rate of continuous cultures. population growth and the environment is the importance we find a similar relationship for the rate of deforestation to increase with rural population density. As the world's population grows, the rate at which it grows increases with it. Relationship Between Population Growth, Shrinkage and Population Age.
How does the world population growth rate today compare with the growth rate at other times in history? Compare and contrast the demographic transition in more developed and less developed countries.
How are population projections made? Data The rate of natural increase is the difference between birth and death rates. It measures the degree to which a population is growing. Since birth and death rates are measured as the number of births or deaths occurring per 1, population, the difference is divided by 10 to convert this rate into a percentage.
Using the birth and death rates from the World Population Data Sheet, calculate the rate of natural increase for five countries or regions. Due to rounding, answers may differ slightly from the rates of natural increase on the data sheet. Find five countries that appear to have reached the fourth stage of the demographic transition in which death rates are higher than birth rates.
Discussion What technological, economic, and social factors might cause levels of mortality and fertility to change? What do you think the prospects are for the changes in birth and death rates in the United States? Three Scenarios, to When could world population stop growing? World population will stop growing when the birth rate equals the death rate; no one knows whether this will happen. The birth rate and the death rate would eventually reach equilibrium several decades after couples average two children each.
This two-child average is called replacement level fertility, because each couple simply replaces themselves, not increasing the size of each generation.
The total fertility rate TFR refers to the average number of children women are having. When the total fertility rate is at replacement 2.
The replacement level TFR is 2. When might it be possible for world population growth to come to an end? The United Nations has projected that growth could end in the latter part of this century if the use of family planning were essentially universal and couples limited themselves to fewer than two children.
Under such a scenario, world population would be about 9 billion by the end of the century and in slow decline. There is certainly no guarantee that this will happen. If couples average more than 2. We do know that world population growth is inevitable in the near term. But there is a wide range of possible world population scenarios. Three plausible projections published by the United Nations in lead to outcomes ranging from 7.
The annual number of births per 1, total population. The annual number of deaths per 1, total population.
Deaths as a component of population change. Total fertility rate TFR: The average number of children a women would have assuming that current age-specific birth rates remain constant throughout her childbearing years usually considered to be ages 15 to Future Growth Population change affects all our lives in a much more immediate way today than it has throughout most of human history.
For the first one-half million years of human existence, the population growth rate was about zero. The population stayed about the same size from year to year. It was not until the s that the modern era of population growth began. Between andthe annual growth rate reached 0. The rate surged to 2. Why has world population grown at such different rates throughout history? Population change results from the interaction of three variables: This relationship is summarized by a formula known as the balancing equation.
The difference between births and deaths in a population produces the natural increase or decrease of a population. Net migration is the difference between the number of persons entering a geographic area immigrants and those leaving emigrants. Natural increase usually accounts for the greatest amount of growth in a population, especially within a short period of time.
For the world, growth occurs only when there are more births than deaths; for individual countries, migration is also a factor. The Mortality Revolution Human population grew rapidly during the Industrial Revolution, not because the birth rate increased, but because the death rate began to fall.
This mortality revolution began in the s in Europe and spread to North America by the mids.
Poverty in relation to population density and growth by Malo's Public Prezi Account on Prezi
Death rates fell as new farming and transportation technology expanded the food supply and lessened the danger of famine. New technologies and increasing industrialization improved public health and living standards. Late in the 19th century, birth rates also began to fall in Europe and North America, slowing the population growth that had resulted from continued moderately higher birth rates than death rates. Sinceboth birth and death rates in the more developed countries have continued to fall in tandem, with a few interruptions.
A worldwide influenza pandemic in caused the death of between 20 million and 40 million people and produced a temporary increase in the death rate. Since the s, birth rates have continued their decline, while death rates declined into the s but have been slowly increasing since. In some European countries, declining birth rates and an increase in death rates are contributing to declining population size.
The total fertility rate TFR in many more-developed countries is well below replacement levels of two children per couple. The Demographic Transition Demographers have attempted to explain the experience of these more developed countries as a demographic transition from high birth rates and death rates to the current low levels. This process tends to occur in three stages. First, birth and death rates are both high, so little growth occurs.
Second, death rates fall due to improved living conditions, while birth rates remain high. During this period population grows rapidly. The third stage of the transition is reached when fertility falls and closes the gap between birth and death rates, resulting again in a slower pace of population growth. All the more developed countries have entered this third stage of the demographic transition, and some have gone on to a fourth stage in which death rates are higher than birth rates, and the population declines.
Components of Population Change In contrast to the more developed countries, the less developed countries—in Asia, Africa, and Latin America—had both higher birth and death rates in the s than Europe and North America had in the s, and these higher rates have continued throughout the 20th century.
In most less developed countries, the mortality revolution did not begin in earnest until after World War II, and it followed a different pattern than that in European countries. Birth and death rates were higher at the start of the demographic transition than they had been in Europe or North America.
Death rates fell rapidly in less developed countries through the introduction of medical and public health technology; antibiotics and immunization reduced deaths from infectious diseases; and insecticides helped control malaria. In the second stage of the demographic transition of these regions, mortality declines led to continued population growth.
With declining mortality and high fertility rates, the population growth of the less developed countries achieved an unparalleled 2. Overall, mortality rates in the less developed countries fell much faster than during the demographic transition in the more developed countries.
As a result, there was a large gap in the percentage of growth between these two regions. Sincebirth rates have fallen in less developed countries, but the death rate has fallen faster. The population growth rate is still high, about 1. While the patterns of fertility decline have varied dramatically throughout the less developed world, many countries are well into the transition process.
Even in sub-Saharan Africa, where birth rates remained high through much of the s and s, fertility rates in most countries are declining. But we can make educated guesses by looking at past and present trends in two of the components of population growth: The third component, migration, can affect the growth of individual countries, but not world population.
World population is projected to increase to 8 billion by and to reach 9. Future of World Population Growth: Three Scenarios, to Source: The population of these regions would almost double by according to moderate projections. Inclose to 90 percent of world population could live in countries currently considered less developed, compared with about 80 percent today.
Terms Birth rate or crude birth rate: Death rate or crude death rate: The historical shift of birth and death rates from high to low levels in a population. The decline of mortality usually precedes the decline in fertility, thus producing rapid population growth during the transition period. The process of leaving one country to take up permanent or semipermanent residence in another.
The number of persons added to or subtracted from a population in a year due to natural increase and net migration; expressed as a percentage of the population at the beginning of the time period. The process of entering one country from another to take up permanent or semipermanent residence.
Rate of natural increase: The birth rate minus the death rate, implying the annual rate of population growth without regard for migration. Expressed as a percentage.
Discussion guide What was the leading cause of death in the United States in ? What proportion of deaths was attributable to this cause in the United States in and in Peru in ? What were the leading causes of death in Peru in ?
How does this compare to the United States in and ? Reading How have life expectancies changed in more developed countries since the Roman Empire? Why are infant mortality rates over in some less developed countries? Find these variables for 10 countries and examine their relationship. Next, examine the relationship between the infant mortality rate, the birth rate, and GNI per capita.
Does AIDS have a significant impact on population growth? The high degree of HIV prevalence worldwide has had an impact on population growth rates. In fact, many believed that AIDS would have little or no impact on population growth. At that time, it was difficult to predict or imagine that there would be any country with 25 percent of the population between the ages of 15 to 49 living with HIV.
- Effects of Population Growth
The plague, or Black Death, killed an estimated 25 million to 35 million people in Europe alone, a number that represented approximately one-third of its population. In some regions, the impact of AIDS has been more pronounced. In nine countries in Africa, at least one out of every 10 adults is HIV positive.
For some countries, the AIDS epidemic has nearly erased improvements in life expectancy achieved in the last 20 years. In southern Africa, one of the worst affected regions, life expectancy has declined from 61 to 49 years over the last two decades. The most direct impact has been the increase in the overall number of deaths. Mortality patterns of adults are much higher than they would have been if AIDS were not so prevalent. Additionally, infant and child mortality rates in some countries are higher than they would have been in the absence of AIDS.
As AIDS reshapes the distribution of deaths by age, it is affecting the population composition of many places. Between anddeaths in eastern Africa were concentrated among young children and older adults, while adults ages 20 to 49 accounted for a smaller share of deaths: However, by the yearit is expected that deaths among adults ages 20 to 49 will double, accounting for almost 30 percent of AIDS deaths. Deaths of large numbers of women in their reproductive years and the lower survival prospects of infected children will also reduce the size of the younger population.
The new age and sex structure for some populations will result in lower growth rates. Still, the overall population size of affected countries is projected to increase due to relatively high fertility levels. Additionally, deaths from HIV have seen a decline in recent years due to the scale-up of antiretroviral treatment.
The greatest impact of the epidemic on population growth is that the rate of growth is now slower. The composition of a population as determined by the number or proportion of males and females in each age category. The age-sex structure of a population is the cumulative result of past trends in fertility, mortality, and migration. Information on age-sex composition is essential for the description and analysis of many types of demographic data. It also causes the number of job seekers to grow, but at the same time, it causes the number of available job positions to grow because a greater population translates to a greater demand for basically anything, so manufacturers and service providers have to expand to compensate for that, and they require more employees to expand to work on assembly lines, as customer service representatives, etc.
Water sources such as rivers, lakes, and rain do not grow. The amount of land available does not grow either, it shrinks. There is more information about the effects of population growth below. If people reproduce less, then there will be less workers to pay taxes, and hence less tax money available to fund pension schemes, but also, the need for everything else reduces that much. The less the population reproduces, the less people there are to get old.
More reproduction would actually, in the long run, increase the need for pension funds because all of the new children would get old eventually, and hence, will need pensions too. Water Supply If water demand increases beyond river supply, then there will be a water deficit. In this case, it is assumed that the river mentioned is the only source of freshwater.
Desalination is sometimes used to supplement shortfalls in water supply. As you can see below, the white area just above the water on the surrounding rock walls of the dam is a sign of a decreased water level.
Human Population: Lesson Plans
Lake Mead at Hoover Dam. Click the image to see a larger version of it. Obtained with thanks from Cmpxchg8b on Wikimedia Commons.
An example of an attempt to supplement shortfalls in water supply is when the National Water Commission of Jamaica hired contractors to transport water from outside of the affected area to the dry spell afflicted area until the dry spell passed. The contractors used water trucks with multi-thousand gallon tanks attached to them to fill residential and business rooftop and elsewhere water tanks so that people could at least wash dishes and do other basic tasks.
Scarcity of Minerals and their Importance Increased population growth increases the demand for basically everything, and everything has to be manufactured using materials. Some of which are rare and expensive, and some of which are abundant and inexpensive. Despite the fact that some materials, such as iron, are abundant and inexpensive, that is just for the moment. The cost of these materials increases as demand increases, due to two reasons: Higher material demand generally entails a price increase, but supply can be increased to remedy this, in the event of a supply shortfall, and improve the demand to supply ratio.
Demand can be considered the rate at which iron reserves are depleted, hence: An increase in supply cannot solve this problem. Recycling is One Remedy Iron ore for example and other material mines are being excavated incrementally, reducing the amount of these materials left. Iron will inevitably become expensive at some point.
Waiting until iron becomes expensive to start recycling or try and find alternatives to it is not a good idea. This is because recycled iron is already affordable.
This also applies to aluminium and copper. Copper is no longer inexpensive, though. This sometimes forces waste management organizations to transport waste to a location outside of the overpopulated area. Landfills are sites at which rubbish decomposes and one environmentally important byproduct of that is methane.Human Population Growth - Crash Course Ecology #3
Methane CH4 is a greenhouse gas which is 20 times more effective at trapping heat in the atmosphere than CO2. Methane from landfills is combustible and is sometimes used to generate heat and power required for factories.
C Johnson did this.