Journal Issue

Climate and Economic Development: Is the location of many developing countries in the tropics a cause of their poverty?

International Monetary Fund. External Relations Dept.
Published Date:
June 1973
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Andrew M. Kamarck

As of the beginning of the Second Development Decade, January 1, 1971, most of the countries in the north and south temperate zones of the world had succeeded in either becoming “rich” (per capita gross national product—GNP—over $1,000) or “middle-income” countries ($300-1,000 per capita GNP). On the other hand, most of the countries with a tropical climate were poor (GNP per capita $100-299) or very poor (under $100). As J. K. Galbraith put it in 1951,

  • … if one marks off a belt a couple of thousand miles in width encircling the earth at the equator one finds within it no developed countries… . Everywhere the standard of living is low and the span of human life is short.

Is the location of today’s poor countries in the tropics an important analytical fact or irrelevant for any consideration of economic development problems? Even if it be important for an understanding of why today’s poor countries are poor, does it have any policy significance in economic development? What, if anything, can be done about it?

Little or no attention has been paid in recent years to any possible influence of climate on economic development. The purely mathematical growth models make no provisions for climatic variables at all, and the subject is generally ignored in leading studies of economic development, even in those dealing specifically with agriculture.

At least part of the present neglect of climate as a factor in economic development is probably due to the strong reaction against earlier theories of geographers, particularly those of Ellsworth Huntington. He maintained that the different climates determined the different levels of civilization through their effects on human energies and achievement. The theory, however, overlooked the comparatively high level of culture attained by some early tropical civilizations even though the level of their material development was low. D. H. K. Lee showed fairly decisively in his work on physical climatology that climate per se does not drastically affect people’s attitudes toward work, leisure, and income. But Lee’s important contributions on the impact of tropical climates on agriculture and on the prevalence of diseases and pests affecting man and his agriculture have been overlooked by economists.

“The human being is inseparable from its environment in each occasion of its existence.”

—Alfred North Whitehead

“Human nature exists and operates in an environment. And it is not ‘in’ that environment as coins are in a box, but as a plant in the sunlight and soil.”

—John Dewey

Thus economists were right to be dissatisfied with theories such as those of Huntington but wrong to assume that this meant that climatic factors could be totally neglected. As Kindleberger has said “the fact remains that no tropical country in modern times has achieved a high state of economic development. This establishes some sort of presumptive case—for the end result, if not for the means.”

There were other forces also at work that may have led to the neglect of the climatic factor in economic development. In the more developed countries where most of the writing on economic problems is done and which set the standards that economists in the less developed countries (LDCs) tend to follow, most economic activity is either independent of climate or increasingly insulated against it. Economic theorists in the more developed countries have concentrated since World War II on building highly abstract models often with little relation to any developed economy that exists now or is ever likely to exist. In these rarefied circumstances, it was even less academically rewarding for analytical work on the real problems facing present-day poor countries which differ from those of interest to the present rich and middle-income countries.

As Kenneth Boulding has commented perceptively:

  • The principal failure of economics, certainly in the last generation, has been in the field of economic development… .

  • One wonders whether culture-boundness may not have something to do with this relative failure. Development, like economics, has been very much a Temperate Zone product. Culture-boundness is manifested primarily in the things we take for granted.

  • … the result of imposing Temperate Zone technique on the tropics, whether in engineering, agriculture, or in economics, may easily be disastrous. This perhaps is the point at which the culture-boundness of economics may be most significant.

Probably also important is the optimism with which people approached economic development problems in the 1950s. This resulted in overlooking the very real unprecedented problems of the poor countries for which no answers as yet existed in the historical experience of the present rich countries.

The effect of climate is clearly not the only ruling constraint on economic development; nor is it suggested that development in today’s poor countries would be unbounded if this effect could be removed. What is claimed is that climatic factors severely hamper development through their impact on both man himself and on his agriculture. Man’s economic activity is directly and adversely affected through the widespread extent and impact of diseases; and tropical agriculture suffers in the quality of its soils, its rainfall, and its multiplicity of pests and diseases.

Little work has been done on these aspects of economic development, so that only a preliminary reconnaissance of the subject is possible. This does show, however, that such problems—while neglected by economic development theory—are finally being recognized and tackled in practice. However, higher priority should be given to research to find ways both of minimizing the adverse impact of climate and of turning particular local climatic conditions to advantage. Clearly, as economic development proceeds in a country, it will become easier to avoid the worst effects and to exploit the advantages of the tropical climate and the climate will become less important as a factor in development.

In essence, there is a “law” parallel to Engel’s law operating here. As development proceeds the proportion of GNP produced in agriculture drops and the importance of the climatic factors affecting agriculture correspondingly drops. Growth in GNP simultaneously permits greater allocation of resources to health problems and the impact of climate thus will be further reduced.

The tropics

The tropical countries include all of the African countries except South Africa and the extreme north of the North African countries; all of South America, except Argentina, Chile, and Uruguay; the Central American and Caribbean countries, including Southern Mexico; and the South and Southeast Asian countries.

There are three main types of tropical climates. The wet equatorial climate—mainly within 5° north and south of the equator—is characterized by constant heat, rainfall, and humidity. Dry tropical climates—lying largely between latitudes 15° and 30° north and south—embrace the hot arid desert areas (e.g., North Africa, Arabia, and Northwest India) where rainfed agriculture is practically impossible. The alternately wet and dry tropical (monsoon) climates are experienced by vast areas roughly between 5° and 15° north and south in South America, West and Central Africa, and Australia.

Despite such variations a few valid generalizations about tropical climates can be made. The average temperature in the coldest month is at least 18° C (64° F) and rainfall rather than temperature determines the seasons—although the variation of rainfall from year to year and within any year is considerable.

This variation can be catastrophic: in July 1972, for example, 4.5 meters of rain fell on the island of Luzon where much of the economic effort of the Philippines has been concentrated. The crop from 1 million acres of rice fields was destroyed as was 30 per cent of the sugar crop which dominates the country’s export earnings. Not only is rainfall usually either too much or too little but drought tends to come in the hottest and windiest part of the year so that loss of water by evaporation and transpiration is high.

The continuous heat and the absence of frost means that life and reproduction can go on throughout the year so there is no temperature constraint to continuous plant growth. Unfortunately there is similarly no constraint to the continuous reproduction and growth of all kinds of pests and parasites on man, his animals, and his crops.

The result is that life over most of the tropics takes on an almost infinite multiplicity of forms, but because of the fierce resulting competition only a relatively few individuals in each generation of any species may survive in any one place. The conditions are ideal for rapid evolutionary change so that, whenever a new plant or animal is introduced in large numbers in a given area, there is a high probability of attack from any one of a multiplicity of existing or new potential predators.

The impact of climate

Let us look a little more closely at two tropical regions, Africa and Brazil, and see how their climate affects them.

Of Africa’s 11.7 million square miles only the North African countries and the Republic of South Africa and Lesotho do not have predominantly some variety of tropical climate. A pervasive continuing influence on Africa’s development, the climate added, in earlier centuries, to other difficult geographical features in keeping the continent isolated from the world. The many tropical diseases kept Africans at subsistence level; yellow fever and malaria levied a heavy death toll on all visitors to tropical areas. Trypanosomiasis carried by the tsetse fly killed horses and cattle and made it impossible to use animal transport to get to the interior from the coast; commerce had to depend on human porters, the most costly and inefficient of all transport systems. The transport obstacle alone was quite sufficient to stop any appreciable African economic development for centuries.

Despite its tropical location, Southern Brazil benefits from its altitude (average temperature in the tropics usually drops by 1° F for every 1,000 feet of elevation) so that its highland climates resemble those of the Eastern Appalachians of the United States. It is precisely in this more favored area that economic development has reached a middle-income per capita level. In contrast, the northeast of Brazil, the problem area with a population of about 30 million, is dominated by tropical dry climates. The area is consequently subject to random recurrent droughts which may last one to three years (the latest one lasted from February 1970 to March 1971) and which effectively halt any development plans. Despite this the main approach to economic development has tended to be investment in fixed capital rather than in the research necessary to find out how best to handle the drought. A great many dams have been built but—because of high evaporation and the peculiar terrain—it might have been wiser to conserve rain where it falls by contour ploughing rather than relying on dams.

Human diseases

The impact of disease on economic development in today’s poor countries has been largely ignored in recent economic literature. Economists working on problems of the more developed countries can justify this: it can be assumed that the average economic man is healthy and that sickness, while not insignificant, is not normally a major factor in the growth and functioning of the economy. But in today’s less developed countries in the tropics this assumption is false. In such areas a person who has not been, or is not being, substantially affected by poor health is the exception; and lack of good health affects attitudes to work, learning ability, and energy and capacity for heavy or sustained work or thought.

The prevalence of disease in tropical areas is well known. It has been estimated, for example, that in the African continent there are, on average, two infections per man and that bilharzia affects nearly half the population. The practical consequences of such handicaps were pointed out to me by a high official of the old Nyasaland Railway; as a rule of thumb he equated two Africans to one European in terms of capacity to do physical labor simply because the average African worker’s strength was sapped by various parasitic diseases and by malnutrition.

Major diseases

The debilitating disease bilharzia affects some 150-200 million people in Africa, the Middle East, and Latin America and countless millions in mainland China. It has been estimated that one variety of the disease reduced working ability of patients from 15–18 per cent in mild cases to 72-80 per cent in severe cases. No effective cure as yet exists, and the disease is spreading as a by-product of irrigation and increased mobility of people.

Malaria, while largely eliminated from the subtropics, is still highly endemic in all of tropical Africa, parts of Central and South America, and West, South, and Southeast Asia. The World Health Organization (WHO) estimated that in May 1972 there were 700 million people under great malaria risk with morbidity rates ranging from 10 to 80 per cent. No effective means of eradication has yet been found for large areas in Africa and limited areas in Central America and Asia. Several species of the mosquito vector have developed immunity to the previously effective insecticides. Further, in Sri Lanka—one of the few tropical areas where malaria was eradicated—it is returning with as many as 2 million cases in 1970.

River blindness is a major constraint on development in Upper Volta, where it prevents cultivation of the most fertile land. It affects mostly adults, and WHO estimates it has resulted in total or significant partial blindness in 20 million people, mostly in Africa but also in limited areas of Mexico, Guatemala, Venezuela, and Colombia and in the Yemen Arab Republic.

There are a large number of other debilitating parasites: intestinal worms infect over a billion people throughout the tropics and subtropics. Hookworm disease infects some 450 million people in these areas, causing anemia, mental and physical retardation in children, and apathy toward work. There are about 250 million people throughout the world with one or another variety of filariasis caused by two species of nematode worms spread by the bite of a mosquito. One of the more unpleasant varieties of this disease is elephantiasis—luckily most of the 100 or so million people infected in Asia have only mild cases of the disease.

A number of other diseases are also significant: more than 10 million people, mostly in Africa and South Asia, are infected by leprosy and most of them are not under treatment. It has recently been found that the curative drug is not as effective as was formerly believed. Kalaazar (“oriental sore”), dengue (“break-bone fever”), and cholera are also significant economic factors from time to time.

Medicine and the tropics

In addition to the diseases that are primarily tropical, the LDCs continue to suffer from many temperate zone diseases, among which tuberculosis is probably the most important. While the LDCs can take over the technology for handling temperate zone disease from the developed countries, no known effective cure or economically feasible prevention measures as yet exist for many tropical diseases. It is highly likely that insufficient resources are devoted to research in this area—a reasonable inference from the lack of attention paid to the problem by development economists and planners.

One reason for this neglect is the introduction to the LDCs of the usual unformulated assumptions with which economists from the developed countries operate. Most medical schools in the LDCs model their training on the medical schools in the more developed countries. Rather than worry about the infectious, parasitic diseases from which the majority of the population suffer, they worry about the same health problems that the doctors in the more developed countries mostly face—cancer, heart disease, etc.—since it is these that their patients, the privileged elites, suffer. In Rio de Janeiro, for example, there is one doctor for every 370 people; in the rest of Brazil, over half the population never see a doctor from birth to death. Tropical disease has, of course, affected development directly. In 1881, de Lesseps failed to build a canal across the Panama Isthmus because of yellow fever and malaria. In 1904-14, the United States successfully built the canal after first undertaking an expensive and widespread program of sanitation to eradicate the disease-carrying mosquitoes; the prerequisite for success was thus preliminary investment in public health. Since then most large-scale construction projects in the tropics have involved steps to protect their workers against the local diseases—but these special measures are not taken for the bulk of the population.

In contrast, when the present industrialized countries were still poor, there was greater recognition of the importance of diseases as a factor in economic development. The report of Sir Edwin Chadwick in 1850 (“The Sanitary Condition of the Labouring Population of Great Britain”), which initiated the modern public health movement, was based on the premise that poverty and disease formed a vicious circle and that action had to be taken against disease if progress against poverty were to be made.

Development finance and health

The contrast is equally striking today. Finance for research on the diseases debilitating the 2 billion people in the LDCs has been only a tiny fraction compared with the resources used in the industrialized countries to try to secure a few more years of life for people there. For example, $1.6 billion was authorized in 1971 for cancer research alone in the United States over several years; research on tropical disease problems in the whole world probably costs less than 10 per cent of this amount.

Help in coping with this problem has been pioneered by WHO and the bilateral aid agencies in the guise of technical assistance. The French Government, in particular, has been active in sponsoring an organization (at Bobo-Dioulasso in Upper Volta) to coordinate action against tropical disease in French-speaking Africa.

The World Bank Group has moved cautiously in considering finance to help in these problems—it began in 1962 to make loans for drinking water and sewerage projects in LDCs. In 1971, it worked out a cooperative arrangement with the WHO under which the latter would help to find and prepare drinking water, sewerage, and storm drainage projects for the World Bank Group. In January 1972, the Group itself made a development credit to Malawi that, for the first time, included provision for control of a disease (bilharzia) as a part of an agricultural development project. Since then disease control or eradication in the area of a rural development project has become a regular feature of Bank loans and credits where project analysts find such provisions economic.

Cooperative international action has also been undertaken against river blindness. A steering committee of WHO, the Food and Agriculture Organization (FAO), and the United Nations Development Program (UNDP) and the World Bank Group was set up in 1972 to plan the joint efforts of these organizations in developing and carrying out a project to control the disease in the Volta River Basin in West Africa. The groundwork for this is now under way.

What has been done so far is no more than a promising beginning. Practically nothing has been done in the way of systematic economic analysis of the various specific disease obstacles to economic development and of the economic and social costs and benefits of projects to remove them. Without such basic information it is impossible for a government or aid agency to choose between investments in disease control and in other more conventional investment projects. In the meantime it is highly improbable that the existing distribution of resources is anywhere near optimal.


One of the principal ways in which the tropical countries differ from the rich and middle-income countries is that so much less is known about how best to exploit and to improve the soil. The LDCs cannot automatically use the knowledge that today’s rich countries acquired when they were poor. Special problems in tropical agriculture, representing major obstacles to economic growth, need to be specifically recognized as such.


In general, with the exception of alluvial or recent volcanic soils, tropical soils tend to be poor, containing little organic material. Even in dense virgin forests—where dead leaves, branches, and trunks constantly return borrowed elements to the supporting soil—the equilibrium is precarious. If the tree or plant cover is removed, the thin layer of humus is soon exhausted or washed away with the first heavy rains.

Good soil is made up of numerous tiny mineral soil particles aggregated into a firm and flexible structure. Intermingled with this skeleton are the organic substances, the “humus,” which is the product of bacteria action on plant litter. But for all these organisms to exist, the soil structure must contain freely circulating air and water. In the tropics, it has to be protected against the heat of the sun, which would burn away the organic matter and kill the micro-organisms; and it has to be protected from the direct blows of the torrential rains, which would crush the structure of the soil, seal off the underlying soil from the air, and leach out the minerals or carry them so far into the earth that the plant roots cannot reach them. When the soil is laid bare its temperature rises and the sun hastens the oxidation and disappearance of the humus; the big swings in the temperature that occur in the tropics between day and night accelerate the mechanical disintegration of the soil; and the rains and the wind erode it.

Over a very large part of the humid tropics, the soil has become laterite so that all that is left is a reddish mottled clay, consisting almost entirely of hydroxides of iron and alumina, which tend to solidify on exposure to air. The pure laterites and latosols (the so-called tropical red and yellow earths) are agriculturally poor or useless.

Over the centuries, the inhabitants of many tropical countries (for example, most of sub-Saharan Africa and parts of India and Sri Lanka) established a method of cultivation to meet the soil conditions confronting them—this was “shifting” or “seminomadic” cultivation. Fields are cultivated for a few years, then allowed to revert to bush jungle to restore fertility for periods that may take up to 20 or 25 years. Although shifting cultivation is superb for survival in difficult conditions—if only at a bare existence level—it has also meant that one of the main advantages of agricultural over a nomadic life—the growth of a settled community—is often not attained.

Character of the food supply

The tropical climate also affects the character of the food supply: the chemical composition of tropical soils tends to perpetuate the shortage of proteins in the diet—a shortage that naturally has an impact on work efficiency.

The shortage of protein (the critical nutrient for physical and mental growth) in the food of children may be a major factor inhibiting development. There is accumulating considerable evidence that there may be a relationship between malnutrition of children, mainly in the form of shortage of protein, and mental retardation.

Agricultural pests and diseases

Another grave disadvantage of the tropics is that they breed so many species hostile to agriculture. Their multiplicity is an obstacle to development; eventually, with adequate research, such multiplicity manifesting itself in a large variety of plants could become a major asset for the tropical countries.

There is insufficient basic knowledge for a systematic summation of the economic impact of the diseases and pests affecting agriculture in the tropics. However, the magnitude of the problem was suggested by the U.S. National Academy of Sciences in its survey, Tropical Health:

  • Intestinal parasites are almost universally distributed in domestic animals throughout the tropical world. The economic effects are multiple and not necessarily confined to mortality in infected animals. These parasites are responsible for retarded development of young animals, reduced yields of milk and meat, lowered wool production, and impaired working capacity of draught animals.

The survey further pointed out that the tropics lack the temperate zone’s low winter temperature which acts as a barrier to the transmission and perpetuation of gastrointestinal parasites. However, governments have begun the attempt to cut losses from diseases and predators by imposing an artificial winter: many tropical cotton-growing countries legislate a dead season by setting a date when crops must be uprooted and burned and a date when planting may begin.

As for crops, Wrigley pointed out in Tropical Agriculture:

  • The tropical environment, which favours the fast luxuriant growth of crops and vegetation, also favours the weeds which compete for moisture and nutrients; and the parasitic fungi, insects, spider mites, eelworms, virus diseases which make for serious reductions in the crops.

One major enemy of tropical agriculture is the gigantic swarms of desert locusts which may attack crops anywhere from West Africa to India (a swarm may fly as much as 1,200 miles nonstop). The red locust has been successfully controlled through international cooperation in recent years, but the desert locust only partially. In both cases, however, control has relied too much on insecticides and there are signs the locusts are building up resistance.

Trypanosomiasis (nagana), a disease carried by the tsetse fly, prevents the raising of cattle and draught animals over the larger part of tropical Africa. As a result most of African agriculture remains in the subsistence stage.

One final example of the multitude of diseases and predators is East Coast fever, a tick-borne disease which kills a half million calves a year in East and Central Africa. Since exotic, nonlocal, breeds of cattle are particularly susceptible to this disease, it has inhibited the upgrading of cattle in this region through cross-breeding. An intensive effort—financed by the UNDP, the three East African Governments, and bilateral aid sources in the United Kingdom and the United States—is underway to find and develop an effective vaccine for cattle.


Research is urgently needed into ways of combating the obstacles imposed on agricultural development by tropical climates and of turning some of the tropical characteristics into assets. Unfortunately, there has, until recently, been little work on tropical agricultural problems other than on some export crops and on tropical wheat and rice.

The present comparatively advanced state of agriculture in the temperate zone took many years to achieve. Although many techniques and solutions cannot be automatically transferred to the tropics, much of the basic theoretical approach is likely to be valid. Kellogg in Soil has outlined the basic approach to soil problems:

  • We have learned that the most efficient systems of soil management are combinations of practices, fitted to the unique kinds of soil in ways that realise the benefits of the many interactions among the separate processes and the several characteristics of the soil.

Since World War II experiments with fertilizer and plant breeding in tree crops have produced remarkably good results in productivity and improved plants. But fertilizers are expensive and little is yet known about either specific deficiencies in plants which need to be made good in tropical soils, nor of how to do this. It took, for example, some 20 years to discover what trace elements (tiny percentages of minerals such as copper, cobalt, etc.) were needed in the Kenyan soil to make possible the successful rearing of non-African breeds of livestock.

Package of techniques

Over the last 70 years, a combination of techniques has been slowly developed to improve agricultural productivity in the temperate climates. Biological engineering has made it possible to create new varieties of plants tailored to meet a planned set of needed characteristics adapted to take advantage of the particular climatic conditions. The plants can, for example, convert large amounts of fertilizer into usable product rather than excessive foliage. In addition, the use of protectants against pests and insects—often uneconomic with old low-yielding varieties—may pay extremely well with high-yielding varieties. Resistance to pests and diseases may also be bred into the plants.

Until recently this “package-of-techniques” approach was not applied to the tropical countries. The experience of the Rockefeller Foundation in developing the high-yielding Mexican dwarf wheat and of the International Rice Research Institute in the Philippines in developing high-yielding rice has shown, however, that such an approach to tropical agriculture can work. A rapid increase in the average yield of a commodity can be achieved through application of a complete package of high-yielding varieties, provision and use of appropriate fertilizer, adequate control of diseases and insect pests, proper planting, cultivation, and irrigation techniques, and the right breed, nutrition and management of animals.

In addition to using fertilizers to offset the poverty of tropical soils, and improved irrigation and drainage to offset erratic rainfall, the “package-of-techniques” approach can take advantage of the heat and absence of frost to produce two or three crops a year.

Hitherto research has generally been underrated by developing countries, partly because in conventional national accounting it is not regarded as “investment,” (see Kamarck, “Capital and Investment,” Finance and Development, June 1971) but partly because international aid agencies have not given a high priority to it. In this regard, another important policy step—which has been largely overlooked—was taken in 1969. The World Bank Group decided to give consideration to financing agricultural research facilities, as appropriate, in the developing countries. So far only one comprehensive program—in Spain—has been worked out and approved for finance. Clearly similar needs exist in many less developed countries and regions.

Less spectacular but more important in its cumulative effect has been the increasing inclusion in the World Bank Group’s agricultural projects of provision for particular applied agricultural research. For example, in the February 1972 credit for the Zou-Borgou cotton project in Dahomey, it was agreed that the project would include research programs into improving the production of cotton, rice, and groundnuts.

The most important step forward for tropical agriculture was taken in 1971 with the formation of the International Consultative Group on International Agricultural Research, jointly sponsored by the FAO, the World Bank Group, and the UNDP, as a mechanism through which priorities for an expanded international agricultural research program on problems of the less developed countries are established and financial support for such a program is mobilized and coordinated. The sums of money involved are comparatively modest—probably increasing to within $50-75 million a year during the near future—but in terms of development impact, the pay-off should be immense. The international research effort will not by itself be enough—it will be necessary for the individual countries and different regions to apply the results—and this will also necessitate additional local adaptive research.

In 1966, Charles E. Kellogg, one of the world’s leading agriculture experts, commented, “This reviewer fully expects that ‘some day’ the most productive agriculture in the world will be mostly in the tropics, especially in the humid parts.” The organization and successful functioning of the Consultative Group gives considerable grounds for hope the “some day” will be decades sooner than Kellogg could have surmised.

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