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The Human Population Scientists disagree on Earth s carrying Every 5 days the global humanpopulation increases by roughly1 million lives. 1 8 million infants born for every800 000 death 400 years ago the humanpopulation started to grow sanitation and agricultural. The pattern of growth isexponentially The limiting factor forpopulation growth are A theoritical model of food. Thomas Malthus 1798 Human population growexponentially Food supply growinglinearly increase by.fixed amount each year Concluded thateventually the humanpopulation size wouldexceed the food supply. Many Factors Drive Human Population Changes in population Fertility Life expectancy Disease. Age structure Migration Changes in population size When demographers When CBR look at population immigration are greater.trends in individual than CDR Emigrationcountries they take into growth rate is Immigration Emigration CBR number of birth. CDR number of death Changes in population size Global population Population growth rategrowth rate CBR for single nation weCDR 10 need to take.immigration andemigration into CBR Immig CDR emigr 10 Doubling time 70 .growth arte Fertility rate Total Fertility Rate TFR Developed countriesestimate of the average Replacement level fertilitynumber of children that each.women in a poulation will bearthroughout her childbearingyears Developing countries e g U S 2 3 person per day . Replacement level fertility Mortality among young isThe TFR requiredto offset thehigher and aTFR ofaverage number of death in a.greater than 2 1 is neededpopulation so that currentto achieve replacement population size remains stable level fertility . Life Expectancy Average number of Infant mortalityyears per life of a new Number of death ofborn within particular children under 1 year ofcountry age 1000 live birth. Life expectancy is Higher Child mortalityin developed countries Number of death of E g in 2008 for U S the children under age of 5 life expectancy was 78 1000 live birthyears overall. Average life expectancies around the world Infant mortality around the world Aging disease The more number of Disease such as HIVelderly within a country which causes AIDS.the higher CDR 22 million death E g U S CDR 8 death between 1990 2007 1000 In Lesotho South Africa Mexico CDR 5 death 23 of adult population 1000 are infected with HIV.That is due to higherstandard of living andhigher number of elderly increase life expectancy Approximately 33 million people were living with.HIV in 2009 22 million in sub Saharan Africa Age Structure Population The populationpyramid illustrate.that it takes time foractions that attemptsto reduce birth tocatch up with agrowing population . Migration Net migration rate U S 3 3 Is the difference immigrants 1000between immigration peopleand emigration in a. Canada 7 immigrants given year 1000 peoplein a country 1000 people Positive Net migration The movement ofmeans people around the.world does not affectthe total number ofpeople on the planet Family Planning As family income increases people have fewer children .There is a link between higher level education andaffluence among females in particular and low birth Family planning is regulation of the number or spacingof offspring through the use of birth control With women option in family planning CBR tend to drop . Many countries such as Kenya and Thailand used familyplanning campaign to lower its growth rate and TFR Total Fertility rate for educated anduneducated women in six countries Population size and consumption interact to.influence the environment Population size is critical factor in the impactof humans on Earth Eating drinking building homes etc requires energy resources . Population and economic development arenot equally distributed around the world The 12 most populous countries in the world Economic Development Of Earth 6 8 billion human habitants 5 6 billion live in.developing countries and only 1 3 billion live indeveloped countries Although only 1 5 of population live in developedcountries they consume half of the world s energy andresources . The average ecological footprint for the world s 30wealthiest countries is 6 4 ha 15 8 acers per capita Contrast that figure with average ecological footprintfor 50 poorest countries 1 0 ha 2 5 acres per capita Economic Development continue. The IPAT Equation Some countries consume large amount ofresources negative impact on environmentalsystem while others live much lightly on the To estimate the impact of human life styles on.Earth scientists developed IPAT equation Impact Population x Affluence X Technology Material possession Last but least A relatively small population can have a high.environmental impact if its affluence leads to highconsumption and extensive use of destructive technology However an affluent nation can more easily takemeasures to reduce its environmental impact through theuse of technology that counters pollution and increases.the efficiency of resources use Rural populations tend to have a high local environmentalimpact but a low global environmental impact Many Factors Drive Human Population. Changes in population size. Fertility. Life expectancy. Disease. Age structure. Migration. Demographers project that the global human population will be between 8.1 -9.6 billion by 2050. By 2100, it is projected to be between 6.8 billion and 10.5 billion. The dashed lines estimated values.