Human+Carrying+Capacity

Please add your estimates of earth's carrying capacity for humans below. Be sure to include: Name of source (person), Estimate (number), Assumptions built in to estimate. Try to proivde at least one unique estimate that hasn't been done before. Bold the one you think is most credible.

Cesare Marchetti: 1000 billion. Admits it is unrealistic, but possible with adequate technological advances. Paul and Anne Ehrlich: 0.5 million. Based on consideration that in 1971 there were 7 times more people than the planet could maintain. user:DavidSu
 * Pearson & Harper: 0.9 billion. Based on grain production and a North American standard of living.**

First carrying capacity estimate: 13.4 billion (Antony van Leeuwenhoek) Sara
 * United Nations Estimate: 5.1 billion (If lifestyles were improving on assumptions made by the UN projects in developing countries but the population that lived in luxury did not grow)**

McConeghy- 40 billion "In fact, they say, we could provide minimum supplies to 40 billion people IF no one lived a luxury modern life style like the average Americans of 2001."


 * Brown, L.R - 7.34-8.97 billion people "If only present grassland can be converted to agricultural land, without deforestation, the world can support a total population of 7.34 billion people under the condition that each country retains the present food-consumption levels."**

Hillel J. Hoffmann 2 billion "Cornell ecologists have calculated that by the year 2100, the planet will be able to provide for only 2 billion humans" user:Jack_Sun

The first two estimates, dating from the l7~ Century, were surprising close to the central range of modern predictions: 6 to 12 billion (Gregory King) and 13.4 billion (Leeuwenhook).


 * The World Hunger Program at Brown University estimated, based on 1992 levels of food production and an equal distribution of food, "the world could sustain either 5.5 billion vegetarians, 3.7 billion people who get 15 percent of their calories from animal products (as in much of South America), or 2.8 billion people who derive 25 percent of their calories from animal products (as in the wealthiest countries)."**

In 1965 Walter Schmitt of the University of California estimated that 30 billion people ultimately may lead "fairly free and enriched lives on this plane user:JunhoKang

//The most credible...// Dr. Matt McConeghy: "After looking at the amount of supplies on the Earth -- how much water, food, etc. -- **some scientists have calculated that the Earth can hold 40 billion people. Some other scientists looked at the same numbers and calculated that the Earth could hold only 2 billion people."** http://mmcconeghy.com/students/supcarryingcapacity.html

Astrobiology ThinkQuest Team: "If you used the "immortal tiger" model which has humans still working as hunter-gatherers, only 100 million humans could be supported by the Earth. However, if you assumed that every possible square kilometer of Earth's arable land was farmed to maximum efficiency and we all crammed together in huge cities, we could have support as many as 30 billion people - 5 times as many as are living now - or more. This is known as the "ant farm" model." http://library.thinkquest.org/C003763/index.php?page=terraform03

Joel Cohen: "There have been a large number of published estimates for the human carrying capacity of the earth; they range from a low of one half billion people to a staggering 800 billion" []

- Paige Anderson

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Technorth.com: "It has been calculated that, prior to human impact, NPP was about 150 billion tons of organic matter per year. By deforestation and other forms of destruction of vegetation, humans have destroyed about 12% of the terrestrial NPP, and now directly use (for food and fiber) or co-opt (by converting productive land to other uses) an additional 27%. Thus we have already appropriated about 40% of the terrestrial food supply, leaving only 60% for the other terrestrial plants and animals. You might conclude from this that we are at 40% of the carrying capacity and that the theoretical maximum human population would therefore be 2.5x the current level i.e. 2.5x5.9 = 15 billion," ====== [] -- Bilal 1240965128

WisdomfromPakistan - in reality only 2 billion to 4 billion people can be supported. An educated guess is 3 billion, the population of humanity after the Second World War and before the green revolution. []

without deforestation, the world can support a total population of 7.34 billion people under the condition that each country retains the present food-consumption levels. - []

- Benjamin Gu
 * WOA (World Population Awareness and World) - Global population could increase to 12 billion by 2050. -** [|**http://www.population-awareness.net/consumption.html**]

The United States Census Bureau: International Data Base stated that the human population in 2040 will be 9 billion. Official population census reports of other countries were submitted to the United States Census Bureau. The offical population census reports are then screen for any inaccurate information through their calculations, methods, and the trends of the human population growth.[]

According to The International Institute for Applied Systems Analysis (IIASA), the total world poppulation in year 2100 is 8.3 billion based on their ten indicators for each year: Total Population, Mean Age, Proportion Below Age 20, Proportion 20-60, Proportion Above Age 60, Proportion Above Age 80, Old Age Dependency Ratio (60+ / 20-60), Life Expectancy Females, Life Expectancy Males, and Total Fertility Rate (TFR). They also update their projection with new evidences every 4 years. []

Population projection tables provide population projections and other demographic data for nearly 200 economies. The input data used for the projections include a base year (mid-2000) population estimate by age and sex, and base period (2000-05) estimates of mortality, fertility and migration. The tables are produced by the World Bank's Human Development Network in consultation with operational staff and country offices. Important inputs to the World Bank Group’s demographic work come from the following sources: census reports and other statistical publications from national statistical offices; Demographic and Health Surveys conducted by national agencies, Macro International, and the U.S. Centers for Disease Control and Prevention; United Nations Statistics Division, //Population and Vital Statistics Report// (quarterly); United Nations Population Division, //World Population Prospects: The 2000 Revision//; Eurostat, //Demographic Statistics// (various years); Centro Latinoamericano de Demografía, //Boletín Demográfico// (various years); and U.S. Bureau of the Census, International Database. http://ibess.wikispaces.com/Human+Carrying+Capacity
 * The World Bank Group** has estimated that the world popluation in 2050 will be 8,903,260,000.

I would say that the world could only contain about 3 billion or the population around the time 1970s because signs of biological degradation indicators, such as decreasing amount of water in rivers, shows that the Earth's natural supply are not enough for the ever growing population. We also have to taken into account of the rate of technological innovation in the population estimate. Because I believe that rate of new technological advances at this time is slower than the rate of population growth. new ways of allowing more people to live sustainably currently under research studies, wich usually takes about a range of 5 years to 30 years. If the research is something complex, such as finding ways to mass produce and hydrogen cells, or mass producing algae, it would require a long time before the research is complete. - Charles Lee

The United Nations Environment Programme's fourth Global Environmental Outlook Report (GEO-4) ：  6 billion humans. I think the estimate is pretty reasonable because it shows a data that shows humans presently require 22 acres per person to support our global average lifestyle. However, the Earth has only 15 acres per person available. Therefore, we are currently over the carrying capacity. [] ** Critical Issues Committee, Geological Society of America: **** 4 billion people ** This estimate is measured base on the calculation of ecological footprint. As we discussed in class before, it is not possible to calculate local carrying capacity. Therefore, the most accurate way to calculate the global carrying capacity is the calculation of ecological footprint. Each year more of our most productive farmland is buried under human structures, and both good and marginal farmland becomes unusable due to poor farming practices, so even the estimate of a sustainable carrying capacity of 4 billion people eating and living as we do may be high.” [] Cornell researches:2billion I think the estimates not very accurate but it is possible since the data is collected from analyzing human needs for fertile land, fresh water, fossil fuel energy and a diversity of helpful natural organisms with fossil fuel being the only non-renewable recourse on the list. By reading the Plan.B3.0, we know that we have to face many environmental problems in the future. [] -Emilie Chien