II. Population and Water Resources

Dr. Toshio Kuroda
Director Emeritus, Population Research Institute,
Nihon University, Japan

Introduction: Population and Water

The world is now facing a great challenge: the tremendous population of humankind and its continuing increase trend. The United Nations projections assume that the population growth rates of different regions will eventually converge. However, recent projections also assume that total fertility rates among more developed and less developed countries will converge to replacement level by 2050, still leaving some countries at a fairly high level.

In order to achieve world population stability, tremendous efforts to implement effective fertility control policy are needed. Boldly tackling environmental threats is critical. Water is a basic requirement of human beings in order to maintain life. Daily life and activities depend on water.

The UN estimates that two-thirds of humanity will face shortages of clean water by 2025. Without sufficient water, the very survival of our species is called into question. Water scarcity is not only fatal for people, but also severely affects industrial activities. In the last
century, technical innovation and medical revolutions helped bring about rapid world population increase, but now the overwhelming size of the population is imperiling the planet's supporting capacity

The following equation can be used to illustrate the relationship between population and the environment.

I = P X A X T Where, I = Environmental impact P = Population size and growth rate A = Living standard / per capita consumption T = Level of technological achievement

Since consumption of water is directly determined by the number of people, and also by rising living standards achieved by rapid development of technology, we must pay serious attention to the enormous size of the world population. The extremely high rate of the increase will be discussed in the next section of this paper.

In any case, this simple equation clearly tells us the importance of reducing population growth rates to alleviate the impact on humankind and on the environment.

I. Current Situation and Future Perspective of Water Resources

Various Patterns of Water Supply

Water supply systems are quite different from country to country, and even within the country. It depends strongly upon ecosystems and geopolitics. In other words, water supply is not uniform. There are several approaches to using water resources. First: the "individual" approach is very popular. Second: the "common" approach to water. For example, the Rhine River in Europe provides water to several countries located along its upper stream and lower stream. A third method is commercial basis approach as in the case of Singapore, which contracts with Malaysia to buy water regularly because Singapore has no water resource of its own. The last one is a global approach, to provide water to countries and areas which are suffering from serious scarcity.

Last Resort: Technological Approach

A final approach to solve the world scarcity of water is clearly to invent technology to distill fresh water from sea water.

A very small example of distilling fresh water from sea water has been applied in Saudi Arabia, where no fresh water is available at all, and is also one of the richest countries due to abundant oil exports. It was able to pay huge amounts of money for the distilling technology. However, it will take more time to develop technology which will be available to meet the demands of world water requirements.

Recently, another new technological development to addresses global warming and water scarcity through generation of electric power by utilizing large differences of temperature between upper and lower currents seems to be full of promise. United Nations has shown interest.

India has already started this grand experiment, assisted by the technical cooperation of professor Dr. Haruo Uehara (professor of energy engineering, Saga University, Japan) to which the Indian government paid about 7 million dollars. This will be the largest power plant of this kind with generation of 1000 kilowatts of electricity.

The United Nations is expected to request member countries to cooperate to take up this powerful project and assist with technical improvement and cost reduction. (Refer to Mainichi Shimbun, February 21, 2004).

II. World Population and Water

Population Explosion

World population has started to show quite an elastic change of increase, never experienced in the history of humankind in the second half of the 20th century. The annual increase rate exceeded two percent per year, and world population increased from 2.5 billion in 1950 to 6.0 billion in 2000, an absolute increase of 3.5 billion. The annual average increment is 70 million.

Such an expansion of world population was named the "Population Explosion", which is now moving from the first stage, 1950-2000, to the second stage, 2000-2050 (See table 1). It is expected that rate of increase of world population has been declining less quickly, and will also continue to be slow in the future, but on the other hand, the total world population will continue to increase, for example, to 8.9 billion by 2050, and even 10 billion by around 2100.

Table 1 : Population Explosion

i ) First Stage: 1950-2000

	1950	2000	Increase
Population	2.5 billion	6.0 billion	3.5 billion
Rate of Increase per year	2.0%	1.3%

Annual increase 80 to 33 million

ii) Second Stage: 2000-2050

	2000	2050	Increase
Population	6.0 billion	8.9 billion	2.9 billion
Rate of Increase per year	1.3%	0.5%

Annual increase 66 million

iii) World population is assumed to gradually approach 10 billion, and stabilize at around 11 billion by 2100.

The equation model cited earlier in this paper clearly demonstrates that world population growth is placing heavy constraints on water resources, bringing about water shortages and scarcity everywhere in the world, with the exception of a few countries.

Regional Differences of Total Fertility Rate Fertility level can be measured more accurately by the total fertility rate than by the crude birth rate (See table 2).

Half a century ago, the average number of children per woman was extremely high, about five children in the world as a whole. It declined to less than three children by 2000, and it will continue to decline and tend to converge upon the replacement level. However, some different levels of TFR will be maintained in certain regions, in particular, the African region with a rate as high as 2.4, which will suggest a serious situation of water scarcity in Africa (See figure 1).

Table 2 : Regional Difference of Total Fertility Rate

Region	1950-1955	1995-2000	2045-2050
World Total	4.99	2.82	2.15
Africa	6.58	5.27	2.39
Asia	5.91	2.70	2.03
Europe	2.57	1.42	1.81
Latin America and Caribbean	5.89	2.69	2.10
North America	3.47	2.00	2.08
Oceania	3.84	2.41	2.06

Source: U.N., World Population Projections: The 2000 Revision (Draft 2001)

Figure 1 : Regional Difference of Total Fertility Rate

Change of Regional Population Distribution

Remarkable differentials of vital rates, birth and death rates will surely bring about unusual changes of population of regions and countries (See table 3 and figure 2)


It is surprising that a tremendous change of distribution of the world's population is expected to occur in the coming half century.

First, the African population will continue to show a very high rate of increase, contrasting with very slow and declining population in Europe. In Africa, population will increase from 0.22 billion in 1950, to 0.8 billion in 2000, and finally 1.8 billion by 2050. European population was much larger than that of Africa in 1950, 0.55 billion versus 0.221 billion. However, the African population exceeded that of Europe by 2000, 0.79 versus 728. Finally, by 2050 the African population is expected to be three times larger than that of the European population, 1.80 versus 0.63 billion. (See figure 2)

This is also good example to show clear evidence of the accelerating severity of water resource issues. Africa is typically represented as the poorest region in the world where massive water shortages are threatening many countries. Accelerating water scarcity may well influence the time to achieve demographic transition process toward the last stage, for example, by significantly influencing high birth and death rates.

Table 3: Variations of Regional Population Distribution in the World 1950, 2000, 2050 (millions)

Region	1950	2000	2050
World Total	2,519	6,071	8,919
Africa	221	796	1,803
Asia	1,400	3,680	5,222
Europe	547	728	632
Latin America and Caribbean	167	520	768
North America	172	316	448
Oceania	13	31	46

Source: U.N., World Population Projections: The 2000 Revision Highlights, 2003

Figure 2 : Change of Distribution of World Regional Population 1950, 2000, 2050

Urbanization of World Population

One of the significant trends of world population is a rapid and worldwide migration flow from rural to urban areas. Urban population in 1950 was only 30%, and increased to close to 50% in 2000. It is expected to rise to around 60% by 2030. In 2030, the urban population in the more developed countries will be 84%, and 56% in the less developed. However, the size of the urban population is dominant in the less developed regions, in which water scarcity is severe. (See table 4).

Table 4 : Urbanization of World Population (%)

Region	1950	1975	2000	2030
World Total	29.7	37.9	47.0	60.3
More Developed	54.9	70.0	76.0	83.5
Less Developed	17.8	26.8	39.9	56.2

Source: U.N., World Urbanization Prospects: 1999 Revision

Figure 3 : Urbanization of World Population

Ageing of World Population

Another crucial issue facing human beings is ageing due to fertility control spreading all over the world. Already in more developed countries even population decline due to fertility lower than mortality, has now universally begun.

This ageing process is quite rapid. (See table 5a)) Population aged 65 and over was only 7% in 2000, and, surprisingly is projected to be 16% in 2050. However, in more developed countries, it could reach 26% in 2050, and even in less developed countries it could be projected to be 15% in 2050.

Another indicator of ageing, the potential support ratio, (see table 5b) suggests the severity of a highly aged society. For example, in 1995 in terms of world population as a whole, 14 working persons could support one elderly person, but only 5 working persons will have to support one aged person. It is clear that aging will accelerate rapidly, but social and economical development will be confronted with various constraints including water issues.

Table 5:

a) Ageing of World Population (%)

(65+)	1950	2000	2025	2050
World total	5.2	6.9	10.4	16.4
More Developed	7.9	14.4	20.9	25.9
Less Developed	3.9	5.1	8.5	15.0

Source: U.N., 1998 Revision

b) Potential Support Ratio (%)

Region	1995	2050
World total	14	5
More Developed	6	3
Less Developed	20	6

Source: U.N., 1998 Revision

Conclusion: Global Approach

Water is the original heaven-sent gift to human beings. We cannot produce water. Every drop of water is very precious. Ironically, water is now becoming big business.

Water covers most of the globe, but very little of it, about two percent, is fresh water. It is estimated that two-thirds of humanity (UN estimates) will face shortages of clean fresh water by 2025. Preserving precious water resources is an urgent global need.

There are two basic approaches to global problems of human survival. The first is to make the world population size harmonious with the supporting capacity of the earth. Second, without sufficient water, the very survival of our species would be impossible. Therefore technological development to distill sea water should be made internationally.

Editor's Note: This article is a summary of a lecture delivered by Dr. Toshio Kuroda at the 2003 Seminar AUICK takes full editorial responsibility for the content, while Dr. Kuroda checked and partly rewrote.