Human population growth: scientific predictions, influence on resources, environment and incidence of malnutrition

Demographic Factors Influencing Demand for Food

Facts and FiguresWorld POPClock Projection - According to the International Programs Center, U.S. Census Bureau, the total population of the World, projected to 7/23/14 is 7,180,824,630http://www.census.gov/popclock/ Most populated countriesChina: 1,355,692,576India: 1,236,344,631US: 318,502,690 (7/23/14)*CIA Factbook

Countries and Areas Ranked by Population: 2014RankCountry Or AreaPopulation1China1,355,692,5762India1,236,344,6313United States318,892,1034Indonesia253,609,6435Brazil202,656,7886Pakistan196,174,3807Nigeria177,155,7548Bangladesh166,280,7129Russia142,470,27210Japan127,103,388

Facts and FiguresPer year: 130 million births, 56 million deaths, increase 74 million people (update, currently about 75 million)Per second: 4.1 births, 1.8 deaths, increase of 2.3

US populationAccording to the U.S. Bureau of the Census, the resident population of the United States was 318,502,690 (7/23/14)One birth every 8 secondsOne death every 12 secondsOne international migrant (net) every 40 seconds (updated, was every 26 sec before 2008, then up to 40 as of January, 2014)Net gain of one person every 13 (new; was 17 in Jan, 2014) seconds (was every 11 sec before 2008)

Latest U.S. Census Bureau Projections, based on 2010 CensusPopulation projected to grow much more slowly over the next several decades, compared with the last set of projections released in 2008 and 2009; levels of births and net international migration are lower in the new projections - reflecting more recent trends in fertility and international migration. (But, recently immigrations is up again d/t better economic picture)Population age 65 and older is expected to more than double between 2012 and 2060, from 43.1 million to 92.0 million. The U.S. will become a plurality nation, where the non-Hispanic white population remains the largest single group, but no group is in the majority.

Age StructureA reflection of the underlying demographic conditions of the preceding decadesAt the same time is an important determinant of future demographic patternsAge structure is important to policy makers due to its impact on two things:Momentum in population growthDependency ratios

Population Pyramids A convenient way to visualize age structure and sex of populationPopulation pyramids represent age cohorts by 5- or 10-year intervalsYoungest cohort is at bottomThey place males on left and females on rightThe graphic presentation of age cohorts can be either actual numbers or percentage distribution

Population Pyramids They can be used to make comparisons from one country to anotherThey can be used to make comparisons from one time period to another within a country

US Population, 2000

US Population, 2025 (old)

US 2025 (new)

US Population, 2050 (old)

US 2050 (new)

Niger Population, 2000

Niger Population, 2025 (old)

Niger, 2025 (new)

Niger Population, 2050 (old)

Niger, 2050 (new)

Momentum in population growthOver long period, population would just reproduce itself if individual couples produced exactly the right number of children to replace themselves, allowing for some children to die before childbearing ageReplacement Rate: In developed countries, this number is just over two children (2.1 children/woman exactly)

Dependency ratiosRatio of dependents to working age adult (defined as those from 15-65 years)Dependents split into groups by age, and two more ratios then defined:The adult dependency ratio is percentage of the population 65 and over divided by the percentage of population between 15 and 65The child dependency ratio is percentage of the population below 15 divided by percentage of population between 15 and 65

Dependency ratiosIn a rapidly growing population, the burden of dependent children per adult is far greater than In a slowly growing population Or one with zero population growth

Age structure of future populationAs living conditions improve, life expectancy will increase, followed by declining fertility rates. This implies smaller percentage of children in future as compared to percentage of adultsFuture population pyramids will be narrower

Measures of populationNumber of births, deaths, immigration, and emigration over a specified time period determines the changes in pop. sizeChanges are expressed numerically:Doubling timeTotal fertility Rate

DT, doubling time in yearsUnited States:1950 150 million, 2006 300 million DT = 56 yearsWorld: 1850 1 billion, 1920 2 billionDT = 70 years1950 3 billion, 2000 6 billionDT = 50 years

Total Fertility RatePer US Census Bureau: The average number of children that would be born per woman if all women lived to the end of their childbearing years and bore children according to a given set of age-specific fertility rates.

TFR, total fertility rateReplacement rate is 2.1 children/woman*United States: 2.06 children born/woman (2010 est.); 2.01 (2014 est.)Niger: 7.68 2011; 6.89 2014 est.Developing countries: 2.9 average, but least developed nations are much higherDeveloped countries: 1.8 averageAlso varies based on income and education*in developing countries, replacement rate is higher due to higher mortality rates, ranging from 2.5 to 3.3

Population Characteristics over TimeFor most of human history, population was stable with growth rate of 0.002% per year.Advances in developed world changed that:17th century advances in science, agriculture, and health practices19th century Industrial RevolutionPopulation quadrupled between 1750-1950 in developed world d/t declining death ratesTransition period lag time till birthrates decrease to balance out lower death rates

Growth and Total Fertility RatesGrowth is slowing down globallyGlobal TFR: 1970s 4.5; 2005 2.7Between 1970-2005:Asia TFR: 5.3 2.6Africa TFR: 6.8 5.4Latin America/Caribbean TFR: 5.1 2.5However, global rate of increase is still at 74 million people each yearAt what number will our population finally stabilize? Projections range from 8-12 billion

Science Magazine Special Issue Populationhttp://www.sciencemag.org.libaccess.sjlibrary.org/content/333/6042.toc

Features of population growthPopulation growth can be exponential in nature - growth starts slowly and speeds up over time:If four children per family (assuming low mortality rates), population will double each generationHowever, the size of the doubling represents more people each time it occurs (exponential)Greater #s of young people in the population lead to greater potential for future growth

Factors Favoring Large Family SizeCommunity PowerRural LifestyleLack of securityHigh infant mortalityFewer educational or occupational opportunities for women

Solutions for OverpopulationFamily Planning ClinicsIncreased education of womenIncreased availability and affordability of healthcareMore equitable distribution of access to resources such as land, jobs, food

Population and the EnvironmentThe 1980s saw an acceleration of worldwide awareness of the environmentThree major problems were identified as creating intense pressure on limited resources:Population growthThe need for increased food productionThe burning of fossil fuels

Population GrowthNever before in human history has our planet been so densely populated as today: more than 7 billion people now live on earthSome of the developing countries are steadily moving toward lower birth and death ratesOthers - mainly those with high levels of poverty and limited social and economic progress for women - are experiencing constant birth rates at a high level

Urban population growthTwo features of population growth make it particularly difficult to achieve future successes on the food security front: The world is becoming more urbanized, and The world is becoming more polarized, i.e. while the number of people in the low-income groups is growing faster than world population in general, the share of income of the rich has been rising significantly

Urban population growthIn most cities in poor countries, the following have lagged behind the urban growth rate of the past three decades:Public investments in new housingEffluent disposalHighwaysTransportationOther infrastructure basics of government services

Some one billion people currently live in slums

More than 220 million urban dwellers lack access to clean drinking waterMore than 420 million do not have access to the simplest latrines and other bare essentials of a decent standard of livingTheir eating patterns differ from those of rural people

UrbanizationHowever, as incomes rise for some urban professional groups - this is expected to be the case particularly in the industrializing Asian countries - People move up the food chain, i.e. consume more livestock products The production of these products either requires more grain or absorbs arable land

The world's agricultural environment is deterioratingWidespread effects of human activities on the environment: Key indicators show that physical condition of the earth is deteriorating, i.e. earth is getting warmerDeforestation of the planet continues unabated, reducing capacity of soils and vegetation to absorb and store water

The world's agricultural environment is deterioratingSoil erosion by water and wind due to inappropriate agricultural techniques as well as overuse of scarce resources, particularly overuse of water resourcesDesertification: Spread of desert to previously fertile areas,Process involving rapid loss of topsoil and, depletion of plant life Occurs d/t combined impact of drought and mismanagement of land by humans

The Global Land Assessment of Degradation (Glasod) Glasod estimates: Of the 3.2. billion hectares under pasture, 21 percent are degradedWhile of nearly 1.5 billion hectares in cropland, 38 percent are degraded to various degreesWater and wind erosion are the principal causes of degradation

The Global Land Assessment of Degradation (Glasod) Glasod estimates: Various sources suggest that 5 to 10 million hectares of land are being lost annually to severe degradationThe degradation of cropland appears to be most extensive in Africa, affecting 65 percent of cropland area, compared with 51 percent in Latin America and 38 percent in Asia

Population Growth and Finite Resources: the Oil ReserveTimescale when this resource is used up is dependent on worldwide consumption rate (very difficult to estimate)A worst case scenario: the Third World aspires to US consumption rate and consumption rate then doublesMost best case scenarios offer a resource exhaustion timescale of about 50-70 years leftNatural gas revolution; fracking - new thoughts

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