HOW MANY PEOPLE CAN THE EARTH SUPPORT
HOW MANY PEOPLE CAN THE EARTH SUPPORT
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DOI：
10.1002/j.2326-1951.1995.tb03209.x
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发表时间：
1995-11-01
期刊：
影响因子：
--
通讯作者：
COHEN, JE
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文献类型：
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作者：
COHEN, JE
1679 年 4 月 25 日，在荷兰代尔夫特，显微镜的发明者安东尼·范·列文虎克 (Antoni van Leeuwenhoek) 写下了对地球所能容纳的最大人口数量的第一个估计。他计算出，如果世界上所有可居住的土地都具有与荷兰相同的人口密度（当时每平方公里约120人），地球最多可以养活134亿人——远少于他的镜头在鳕鱼精中显示的精子数量。在随后的几个世纪里，范·列文虎克的估计被许多类似的计算所遵循。 1695 年左右，一位名叫格雷戈里·金 (Gregory King) 的伦敦人估计，地球上的“如果人口充足的话，这片土地最多可以养活”125 亿人。 1765 年，德国团牧师约翰·彼得·苏斯尼尔希 (Johann Peter Sussrnilch) 将自己的数字（139 亿）与范·列文虎克、法国军事工程师塞巴斯蒂安·勒普雷斯特·德沃邦（Sebastien Le Prestre de Vauban）（55 亿）和英国作家兼制图师托马斯·坦普尔曼（Thomas Templeman）（115 亿）的估计进行了比较。近几十年来，对最大人口的估计比以往任何时候都更加广泛和快速。在“承载能力”的标题下，它们经常出现在环境辩论、联合国报告以及受过生态学、经济学、社会学、地理学、土壤科学或农学等学科训练的学者或学术政治家的论文中。然而，人口统计学家却出奇地保持沉默。在美国人口协会 1992 年和 1993 年年会上举行的 200 多次研讨会中，没有一次会议涉及估计或定义地球任何区域的人类承载能力。相反，专业人口统计学家倾向于关注人口的构成和增长，将他们的预测限制在近期——通常是未来几十年——并用有条件的术语来构建它们：如果出生率、死亡率和移民率（按年龄、性别、地点、婚姻状况等）是这样那样，那么人口规模和分布也会是这样。这种条件预测或预测可以成为强大的工具。联合国的预测戏剧性地表明，如果世界各主要地区的人口继续以 1990 年的速度增长，那么人口将在 160 年内增加 130 倍以上，从 1990 年的约 53 亿增加到 2150 年的约 6940 亿。这些数字对未来的平均生育水平极其敏感。假设，如果从 1990 年开始，平均夫妇的生育率逐渐达到仅比更新自己所需的孩子多十分之一的水平，那么世界人口将从 1990 年的 53 亿增长到 2050 年的 125 亿，到 2150 年增长到 208 亿。相反，如果（再次假设）从 1990 年开始及此后，夫妇生育的孩子数量恰好等于更新所需的孩子数量就其本身而言，世界人口将从 1990 年的 53 亿增长到 2050 年的 77 亿，到 2150 年将稳定在 84 亿左右。明确的信息是，人们平均生育的孩子数量不可能永远超过替代自身所需的数量。这不是一个意识形态口号；而是一个意识形态口号。这是一个铁的事实。传统农业无法为 6940 亿人生产足够的粮食；从天而降的水不够多。地球的有限性保证了人类数量的上限确实存在。那些天花板在哪里？有些人认为，对人口数量的任何限制都是如此遥远，以至于它的存在与目前的担忧无关。另一些人宣称，从长远来看，人口数量已经超过了地球所能容纳的数量（通常没有具体说明多长时间）。还有一些人承认短期限制可能存在，但是……
On APRIL 25, 1679, IN DELFT, HOLLAND, the inventor ofthe microscope, Antoni van Leeuwenhoek, wrote down what may be the first estimate of the maximum number of people the earth can support. If all the habitable land in the world had the same population density as Holland (at that time about 120 people for every square kilometer), he calculated, the earth could support at most 13.4 billion people-s-far fewer than the number of spermatozoans his lenses had revealed in the milt ofa cod. In subsequent centuries, van Leeuwenhoek's estimate has been followed by dozens of similar calculations. Around 1695 a Londoner named Gregory King estimated that the earth's" Land If fully Peopled would sustain" at most 12.5 billion people. In 1765 a German regimental pastor, Johann Peter Sussrnilch, compared his own figure (13.9 billion) with the estimates ofvan Leeuwenhoek, the French military engineer Sebastien Le Prestre de Vauban (5.5 billion) and the English writer and cartographer Thomas Templeman (11.5 billion). In recent decades estimates ofmaximum population have appeared thicker and faster than ever before. Under the rubric of" carrying capacity" they crop up routinely in environmental debates, in United Nations reports and in papers by scholars or academic politicians trained in ecology, economics, sociology, geography, soil science or agronomy, among other disciplines. Demographers, however, have been strangely silent. Of the more than 200 symposiums held at the 1992 and 1993 annual meetings ofthe Population Association ofAmerica, not one session dealt with estimating or defining human carrying capacity for any region ofthe earth. Instead, professional demographers tend to focus on the composition and growth ofpopulations, restricting their predictions to the near term-generally a few decades into the future--and framing them in conditional terms: ifrates ofbirth, death and migration (by age, sex, location, marital status and so on) are suchand-such, then population size and distribution will be so-and-so. Such conditional predictions, or forecasts, can be powerful tools. Projections by the UN show dramatically that if human populations continued to grow at 1990 rates in each major region ofthe world, thenthe population would increase more than 130-fold in 160 years, from about 5.3 billion in 1990 to about 694 billion in 2150. Those figures are extremely sensitive to the future level of average fertility. If, hypothetically, from 1990 onward the average couple gradually approached a level offertility just onetenth ofa child more than required to replace themselves, world population would grow from 5.3 billion in 1990 to 12.5 billion in 2050 and 20.8 billion in 2150. In contrast, if (again hypothetically) starting in 1990 and ever after couples bore exactly the number ofchildren needed to replace themselves, world population would grow from 5.3 billion in 1990 to 7.7 billion in 2050 and would level off at around 8.4 billion by 2150. The clear message is that people cannot forever continue to have, on average, more children than are required to replace themselves. That is not an ideological slogan; it is a hard fact. Conventional agriculture cannot grow enough food for 694 billion people; not enough water falls from the skies. The finiteness ofthe earth guarantees that ceilings on human numbers do exist. Where are those ceilings? Some people believe that any limit to human numbers is so remote that its existence is irrelevant to present concerns. Others declare that the human population has already exceeded what the earth can support in the long run (how long is usually left unspecified). Still others concede that short-term limits may exist, but …