Challenge+-+3+estimates

Come up with 3 estimates of the worlds carrying capacity - Number, who, what are the assumption of the estimates..

Carrying Capacity Estimates Shunji Murai – “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. Supposing that the current rate of population increase, 1.7 per cent per annum, continues, the world's population carrying capacity will become critical in only about 20 years.”

http://www.unu.edu/unupress/unupbooks/uu03pe/uu03pe0c.htm

De Wit – “1967 - **1000 billion people** – based on Photosynthesis”, “Even then, note that De Wit’s estimates included conditions that if people wanted a million calories a year plus 1,500 square meters to live and work and play, and there were no other limits, then only 79 billion people could be accommodated.” http://www.ecifm.rdg.ac.uk/pop2.htm A. R. Palmer – “If we maintain our current footprint and the human population of 2050 (estimated at 9 billion) reaches consumption levels similar to ours, which is a practical goal for the developing world, humanity would need 13.5 billion acres of land for food production and 14.4 billion acres for wood products on a steady-state basis to be sustainable, and we would have degraded about 3.6 billion acres for human structures. For humans alone, excluding the needs of other organisms, there is not that much land available simply by considering these three computable sorts of personal footprints! Furthermore, the food footprint calculations cited above used U.S. yields, which are significantly higher than average global yields. If global yields were used in those calculations, our food footprints would be closer to 3 acres. Earth’s carrying capacity for a population with 3-acre food footprints might be no more than about **4 billion people** (12 billion acres of arable, crop and pasture land ÷ 3).” http://bcn.boulder.co.us/basin/local/sustain6.htm

1200211026

http://library.thinkquest.org/C003763/index.php?page=terraform03
 * No author but is on a database ThinkQuest**- "While it might be attractive for us to give you a definitive number for the carrying capacity of Earth, it simply isn't possible. For example, 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."

When some scientists say that the carrying capacity of Earth is 40 billion, then they are saying that IF the rich people would give up all their luxuries such as cars, electricity, education, clean water, meatm etc. then that would allow us to provide minimum amounts of supplies to a much larger number of people. 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." http://mmcconeghy.com/students/supcarryingcapacity.html
 * Dr. McConeghy** (two assumptions) "When scientists say that the carrying capacity of the Earth is 2 billion, they are not forgetting that we have 6 billion already. What they are saying is, that if you add up all the supplies in the world, and divide them up according to the amount that a typical American uses, then there is only enough for 2 billion people. If we have 6 billion people, the amount of fuel, water, electricity, etc. is just not enough to go around. Some people are going to be left out. Only about 1.2 billion people live in MDCs while the other 4.8 billion people have to make do with less.

Table 3 summarizes the estimates from Cohen's book that do consider social sustainability as well as estimates from other sources. The estimates vary from 0.5 to 14 billion depending on the metric used and the standard of living and technological improvements that are assumed. The medians of the low and high estimates provide a range from 2.1 to 5.0 billion people. With the current Earth population estimated to be 6.1 billion people, the median range of sustainable carrying capacity estimates suggests that the Earth's population be reduced in order to be sustainable." http://www.ilea.org/leaf/richard2002.html
 * Written by Gigi Richard, predicted by Professor Joel Cohen** "When one considers the array of factors that must be estimated and the conditions that must be assumed, it is unrealistic to expect a unique figure defining the Earth's human carrying capacity. Professor Joel Cohen in his 1995 book, How Many People can the Earth Support?, summarized estimates of human carrying capacity of the Earth beginning with estimates made as early as the 1600's. His summary is not limited to estimates that are considered socially sustainable as he includes estimates that only consider biophysical parameters. Many studies cited by Cohen give a range of population carrying capacities with a low estimate and a high estimate. In his 1995 Science paper, Cohen computed the median of the high estimates and the median of the low estimates. The result was a range of medians from **7.7 to 12 billion** people.


 * //PAIGE ANDERSON//**

1 billion - Hulett/1970 - based on food, wood producs and nonrenewable resources. 14 billion - Heilig/1993 - NPP for biophysical capacity/increased technology. And then Prof. Cohen. =/

-CThomas

1. Shunji Murai - 7.34 billion (same as Kevin Tocao's) 2. Thinkquest Database - 30 billion (same as Paige Anderson's) 3. Gretchen C. Daily & Paul R. Ehrlich - less than 5.5 billion - Current (199_) population only being maintained through exhaustion and dispersion nof one-time inheritance of natural capital. -- Jen Wang

1. Anton Van Leeuwenhook (1673-1723) <-- love the name huh? 13.4 billion people. 2. Justus Von Liebig, 1 or 2 billion people living in prosperity to 33 billion people fed on minimum rations. 3. Scientists generally believe approximately 12 billion people. The rest of mine were on Mr. Plamans articles :) Meghan Hoodhood

1. Smil 1994 10-11 billion Food consumption 2. Ferguson 2001 2.1 billion Based on energy consumption and CO2 emissions 3. Palmer 1999 9 billion Standard of living lower than US currently and improvements on energy efficiency, food production and pollution control -Cassandra

1. The UN: 7.8 billion-12.5 billion (Food consumption) [|www.popline.org/docs/1125/110021.html] 2. Dr. McConeghy: 40 billion http://mmcconeghy.com/students/supcarryingcapacity.html 3. (No author): 4 billion-16 billion (land use and energy consumption) http://findarticles.com/p/articles/mi_m402/is_n2_v18/ai_17966623 - Natalie K

1. Rees: 4.3-6 billion (1996)- This is based on ecological footprint and on the assumption that everyone would be enjoying a relatively high standard of living. 2. Pimentel: 2 billion (1999)- Basis of estimation is energy and assumption that everyone would be enjoying a high standard of living is made. 3. Brown & Kane: 2.5-10 billion (1999)- basis of estimation is food and consumption. -Vanessa Lloyd