BBC - GCSE Bitesize - Popul..

12
Population numbers change over time, influenced by births, deaths and migration into or out of the area. Global population levels, having grown slowly for most of human history, are now rising. Population pyramids show the structure of a population by comparing relative numbers of people in different age groups. Population structures differ markedly between LEDCsLEDC: A Less Economically Developed Country [LEDC] has low levels of development, based on economic indicators, such as gross domestic product (the country's income). More of the countries in the southern hemisphere (eg countries in southern Africa, southern Asia and South America) are LEDCs, while more of the countries in the northern hemisphere are More Economically Developed Countries [MEDCs]. and MEDCsMEDC: A More Economically Developed Country [MEDC] has high levels of development, based on economic indicators, such as gross domestic product (the country's income). More of the countries in the northern hemisphere are MEDCs, eg UK, USA, Canada, Europe. More of the countries in the southern hemisphere are Less Economically Developed Countries [LEDCs].. Demographic transition models show population change over time - and also show marked differences between LEDCs and MEDCs. At present the world's population is growing quickly, though this has not always been the case. BBC - GCSE Bitesize - Population change and structure http://www.bbc.co.uk/schools/gcsebitesize/geography/population/pop_... 1 of 12 4/11/2010 8:38 PM

Transcript of BBC - GCSE Bitesize - Popul..

Page 1: BBC - GCSE Bitesize - Popul..

Population numbers change over time, influenced bybirths, deaths and migration into or out of the area. Globalpopulation levels, having grown slowly for most of humanhistory, are now rising.

Population pyramids show the structure of a population bycomparing relative numbers of people in different agegroups. Population structures differ markedly betweenLEDCsLEDC: A Less Economically Developed Country [LEDC]has low levels of development, based on economic indicators,such as gross domestic product (the country's income). Moreof the countries in the southern hemisphere (eg countries insouthern Africa, southern Asia and South America) are LEDCs,while more of the countries in the northern hemisphere areMore Economically Developed Countries [MEDCs]. andMEDCsMEDC: A More Economically Developed Country[MEDC] has high levels of development, based on economicindicators, such as gross domestic product (the country'sincome). More of the countries in the northern hemisphere areMEDCs, eg UK, USA, Canada, Europe. More of the countries inthe southern hemisphere are Less Economically DevelopedCountries [LEDCs]..

Demographic transition models show population changeover time - and also show marked differences betweenLEDCs and MEDCs.

At present the world's population is growing quickly, though thishas not always been the case.

BBC - GCSE Bitesize - Population change and structure http://www.bbc.co.uk/schools/gcsebitesize/geography/population/pop_...

1 of 12 4/11/2010 8:38 PM

Page 2: BBC - GCSE Bitesize - Popul..

The graph shows this pattern of accelerating growth:

World population growth 500BC - 2025

The three main causes of population change are:

Births and deaths are natural causes of population change.The difference between the birth rate and the death rate of a

BBC - GCSE Bitesize - Population change and structure http://www.bbc.co.uk/schools/gcsebitesize/geography/population/pop_...

2 of 12 4/11/2010 8:38 PM

Page 3: BBC - GCSE Bitesize - Popul..

country or place is called the natural increase. The naturalincrease is calculated by subtracting the death rate from thebirth rate.

natural increase = birth rate - death rate

The rate of natural increase is given as a percentage,calculated by dividing the natural increase by 10.

For example if the birth rate is 14 per 1000 population, and thedeath rate is 8 per 1000 population, then the growth rate = 14 -8 = 6

That is 6/1000, which is equal to 0.6%.

Rates of population growth vary across the world. Although theworld's total population is rising rapidly, not all countries areexperiencing this growth. In the UK, for example, populationgrowth is slowing, while in Germany the population has startedto decline. MEDCsMEDC: A More Economically DevelopedCountry [MEDC] has high levels of development, based oneconomic indicators, such as gross domestic product (thecountry's income). More of the countries in the northernhemisphere are MEDCs, eg UK, USA, Canada, Europe. Moreof the countries in the southern hemisphere are LessEconomically Developed Countries [LEDCs]. have lowpopulation growth rates, with low death rates and low birthrates.

Population will decline if death rate is greater than birth rate.

LEDCsLEDC: A Less Economically Developed Country [LEDC]has low levels of development, based on economic indicators,such as gross domestic product (the country's income). Moreof the countries in the southern hemisphere (eg countries insouthern Africa, southern Asia and South America) are LEDCs,while more of the countries in the northern hemisphere areMore Economically Developed Countries [MEDCs]. have high

BBC - GCSE Bitesize - Population change and structure http://www.bbc.co.uk/schools/gcsebitesize/geography/population/pop_...

3 of 12 4/11/2010 8:38 PM

Page 4: BBC - GCSE Bitesize - Popul..

population growth rates. Both birth rates and death rates inLEDCs tend to be high. However, improving healthcare leads todeath rates falling - while birth rates remain high.

Population will increase if death rate is less than birth rate.

The table shows data in selected LEDC and MEDC countries.The figures are per 1000 of the population per year.

In Bulgaria, the birth rate is 9/1000 and death rate is 14/1000. Asbirth rate is less than the death rate, Bulgaria has a decliningpopulation.

In South Africa, the birth rate is 25/1000 and death rate is15/1000. South Africa has an increasing population with apopulation growth rate of 1%.

The demographic transition modeldemographic transition

BBC - GCSE Bitesize - Population change and structure http://www.bbc.co.uk/schools/gcsebitesize/geography/population/pop_...

4 of 12 4/11/2010 8:38 PM

Page 5: BBC - GCSE Bitesize - Popul..

model: The demographic transition measures populationchange over time, by studying birth rate and death rate. Instage one the high birth rate balances (matches) the high deathrate. In stage two, the total population starts to rise as deathrates start to fall, but birth rates remain quite high. In stagethree, the population is still growing, but the gap between thebirth rate and death rate narrows. In stage four, the totalpopulation is high, but it is balanced due to a low birth rate anda low death rate. shows population change over time. It studieshow birth rate and death rate affect the total population of acountry. It is divided into five stages:

As a country passes through the demographic transition model,the total population rises. Most LEDCsLEDC: A Less

BBC - GCSE Bitesize - Population change and structure http://www.bbc.co.uk/schools/gcsebitesize/geography/population/pop_...

5 of 12 4/11/2010 8:38 PM

Page 6: BBC - GCSE Bitesize - Popul..

Economically Developed Country [LEDC] has low levels ofdevelopment, based on economic indicators, such as grossdomestic product (the country's income). More of the countriesin the southern hemisphere (eg countries in southern Africa,southern Asia and South America) are LEDCs, while more ofthe countries in the northern hemisphere are MoreEconomically Developed Countries [MEDCs]. are at stage 2 or3 (with a growing population and a high natural increase). MostMEDCsMEDC: A More Economically Developed Country[MEDC] has high levels of development, based on economicindicators, such as gross domestic product (the country'sincome). More of the countries in the northern hemisphere areMEDCs, eg UK, USA, Canada, Europe. More of the countries inthe southern hemisphere are Less Economically DevelopedCountries [LEDCs]. are now at stage 4 of the model and somesuch as Germany have entered stage 5.

The demographic transition model

As populations move through the stages of the model, the gapbetween birth rate and death rate first widens, then narrows. Instage 1 the two rates are balanced. In stage 2 they diverge[diverge: move away from each other ], as the death rate falls

BBC - GCSE Bitesize - Population change and structure http://www.bbc.co.uk/schools/gcsebitesize/geography/population/pop_...

6 of 12 4/11/2010 8:38 PM

Page 7: BBC - GCSE Bitesize - Popul..

relative to the birth rate. In stage 3 they convergeconverge:move towards each other again, as the birth rate falls relative tothe death rate. Finally in stage 4 the death and birth rates arebalanced again but at a much lower level.

The demographic transition model has two limitations:

Population structure means the 'make up' orcompositioncomposition: composition is what something ismade up of of a population. Looking at the population structure

BBC - GCSE Bitesize - Population change and structure http://www.bbc.co.uk/schools/gcsebitesize/geography/population/pop_...

7 of 12 4/11/2010 8:38 PM

Page 8: BBC - GCSE Bitesize - Popul..

of a place shows how the population is divided up betweenmales and females of different age groups.

Population structure is usually shown using a populationpyramid. A population pyramid can be drawn up for any area,from a whole continent or country to an individual town, city orvillage.

The following graphs show the population pyramids of anMEDC (the UK) and an LEDC (Mozambique), for 2000 and in2025 using projected figures. The left side of each pyramidshows the number of men in each age group, the right sideshows the number of women in each age group.

Population pyramid for the UK 2000

Notice how in the UK 2000 pyramid there is a bulge in the areaof the 30-34 and 35-39 age groups, with the numbers thereafterreducing fairly steadily as the ages increase. This matchesstage 4 of the demographic transition model.

BBC - GCSE Bitesize - Population change and structure http://www.bbc.co.uk/schools/gcsebitesize/geography/population/pop_...

8 of 12 4/11/2010 8:38 PM

Page 9: BBC - GCSE Bitesize - Popul..

Projected population pyramid for the UK 2025

Compare this to the 2025 pyramid, which would be stage 5 inthe model. Here the bulge extends much further, covering theage groups 30-64, with the numbers beginning to reducesignificantly only after 64.

Now compare the UK population pyramids with those forMozambique:

BBC - GCSE Bitesize - Population change and structure http://www.bbc.co.uk/schools/gcsebitesize/geography/population/pop_...

9 of 12 4/11/2010 8:38 PM

Page 10: BBC - GCSE Bitesize - Popul..

Population pyramid for Mozambique 2000

In this graph, notice that in 2000 the 0-4 age group containedthe largest number of people, with the numbers thereafterdeclining steadily as the ages increase. The graph matchesstage 1 in the model.

Projected population pyramid for Mozambique 2025

BBC - GCSE Bitesize - Population change and structure http://www.bbc.co.uk/schools/gcsebitesize/geography/population/pop_...

10 of 12 4/11/2010 8:38 PM

Page 11: BBC - GCSE Bitesize - Popul..

In the second graph, the largest group in Mozambique in 2025is still the 0-4 age group, but there are nearly as many people inthe 5-29 age groups. Now the population pyramid matchesstage 2.

Key things to know about population pyramids:

BBC - GCSE Bitesize - Population change and structure http://www.bbc.co.uk/schools/gcsebitesize/geography/population/pop_...

11 of 12 4/11/2010 8:38 PM

Page 12: BBC - GCSE Bitesize - Popul..

Now try a Test Bite

Back to Revision Bite

BBC - GCSE Bitesize - Population change and structure http://www.bbc.co.uk/schools/gcsebitesize/geography/population/pop_...

12 of 12 4/11/2010 8:38 PM