I. Introduction

This report presents a summary assessment of the environmental situation and challenges facing Trinidad and Tobago at the present time and over the next half-century. The report uses data from standard sources to make a series of projections of population, arable land, forested land, and population carrying capacity for the nation. These projections show that if current population growth and resource utilization trends continue over the next several decades as in the past, the size of the gap between Trinidad and Tobago's population and the population carrying capacity of the available arable land will increase substantially. In the near-term future, this difference will bring to bear continued and increasing pressure to continue the clearing of the nation's forests. In the long run, the large gap between projected population and the carrying capacity of the land suggest that the potential for severe environmental degradation in Trinidad and Tobago is very high.

This report presents solely a summary assessment of the current and future situation; it does not identify, describe, evaluate, or recommend policy actions that can address the situation. The development of suitable policy actions will require much additional analysis, a high level of coordination among the various sectors of the nation, inspired leadership, and participation of the nation's citizens in making and implementing difficult and far-reaching decisions.

The summary assessment of this report reveals that a daunting task faces Trinidad and Tobago's environmental planners and managers, if the island nation is to avoid massive environmental damage in the not-too-distant future. This report is based on projections of current trends on population growth and resource utilization. If steps are taken to change those trends, the prospects of a bleak future can be changed. With clear vision and bold action, the Government of Trinidad and Tobago can succeed in preserving an environment in which the human population of Trinidad and Tobago can thrive in harmony with nature.

II. Data Sources

Environmental problems are particularly difficult to address because they are regional in scope, involve many different sectors, and are dynamic (evolve over time). Because the environment is part of a large, complex, dynamic system, a "systems" approach is required to develop a clear understanding of the problems and develop satisfactory strategies for addressing those problems. Assessment of environmental problems involves the physical sciences of physics, chemistry, biology, geology, and meteorology. In addition, however, viable solutions to environmental problems are critically dependent on economic, political, and sociological factors as well.

The summary assessment presented in this report makes no attempt to describe Trinidad and Tobago's environment in detail, and it describes the environmental situation only in broad macroscopic terms. It examines the salient features of the nation from the points of view of population, agricultural resources, and economics, to obtain a rough picture of the current and future situation. This situation assessment utilizes data that are readily available from standard sources on the most important factors affecting the environment. More detailed and refined analysis will no doubt involve the use of much more detailed data on a much wider range of factors.

The principal data used in this report are vital statistics, demographic, economic, and environmental data available from publications of the United Nations and World Bank, such as the World Development Report 1994 (Reference 1), The State of World Population 1994 (Reference 2), and Family Planning and Population: A Compendium of International Statistics (Reference 3), and World Resources 1994-95: A Guide to the Environment (Reference 4). Additional references are listed in the list of references at the end of the report. Throughout this report, the source of each data element used will be provided. In many cases, more detailed or more recent may be available from sources in Trinidad and Tobago (which were not available for this quick assessment). Examples include detailed age-structure data, life tables, regional data (e.g., regional economic data, urban/rural data, environmental data), and racial/cultural data (e.g., race-specific fertility and mortality rates).

Appendix A contains a detailed presentation of all of the data used to make the population projections used in this report, and Appendix B contains a table containing all of the population and other projections (arable land, forested land, arable-land productivity, and carrying capacity). Appendix C presents a summary of some basic environmentally related statistics about Trinidad and Tobago.

III. Projection of Arable Land Area

One of the most important factors affecting the environment is the availability of arable land. If a country's available arable land is sufficient to feed the population, the pressure on the environment is substantially less than if it is not. If the gap between a nation's food needs and its food production resources widens, the nation may make up the shortfall by purchasing food on the world market. In the long run, however, nations of modest economic means must rely heavily on their own resources. As population increases, pressure is placed on agricultural land (forested and arable land) in two ways -- for food production and for physical living space.

This section projects the availability of Trinidad and Tobago's agricultural land resources -- its arable land (cropland) and forests. It does not examine marine food production, since this is a relatively small component of the nation's food supply (Reference 1: 3.6% of total daily protein supply from fish products). The projections made in this section are based on the assumption that current trends in population and agricultural resource utilization continue.

The total land area of Trinidad and Tobago is 5,128 square kilometers (Reference 5). In 1986, the Food and Agriculture Organization of the United Nations reported (Reference 6) that 23% of Trinidad and Tobago's total land was arable -- a total of .23 x 5,128 = 1,179 square kilometers. Reference 4 reports the amount of cropland in 1991 as 1,200 square kilometers -- about the same. Reference 4 reports that the amount of cropland has increased by 3.4% from 1979-81 to 1989-91. (This corresponds to a figure of 1,161 km² for 1980.)

Major factors affecting the availability of arable land are water availability (for irrigation) and deforestation. Reference 6 reports that in 1986, 19% of the arable land area was irrigated, or .19 x 1,179 = 224 square kilometers. Reference 4 reports that over the periods 1979-81 and 1989-91, irrigated land comprised 18% of cropland. Further, it reports that the annual withdrawal of water resources was 3% of total freshwater resources, of which 35% is used in agriculture, 38% in industry, and 27% in domestic uses. In view of the relatively low withdrawal of total reserves, it does not appear that water availability is a major constraining factor on availability of arable land.

Reference 6 reported that in 1986, 44% of Trinidad and Tobago's total land area was forested -- .44 x 5,128 = 2,256 square kilometers. Reference 4 reports that the total forest and woodland in 1989-91 was 2,200 km², and that this was a change of -4.3% from 1979-81. Reference 4 reports that the total forest area (which is natural rain forest) was 1,550 km² (30%) in 1990 and 1,920 km² in 1980, corresponding to an average annual rate of deforestation of total forest over the period 1981-90 of 37 square kilometers, or 1.9% (2.2% compound rate). Reference 1 reports that only 200 square kilometers is nationally protected.

These statistics show that Trinidad and Tobago is being deforested at a very rapid rate. If the rate of deforestation experienced over the last decade continues, destruction of Trinidad and Tobago's remaining natural forest will be total within 40 years.

Deforested areas may be converted to agricultural uses, such as tree farms (plantations) or cropland, depending on the nature of the soil and availability of agricultural inputs (water, fertilizer, pesticides, equipment) and demand for alternative uses (e.g., roads, housing). According to the data on deforestation and arable land availability over the past decade, the extensive deforestation has not been associated with an increase in the amount of arable land. This is not surprising, in view of the nation's high population growth rate -- 1.2% per year in 1960-65, 1.3% in 1985-1990, and 1.1% in 1990-95 (Reference 3). The rate of population growth in Trinidad and Tobago is comparable to the rate of deforestation (1.3% vs 1.9%). In view of the data, the massive deforestation of Trinidad and Tobago is not being accompanied by a concomitant increase in the amount of arable land. (It would appear that the deforested land is either not arable, not being used as arable land, or is being used to offset comparable losses of arable land (e.g., to provide nonagricultural land for the increasing population), but readily available data shed no light on this; local data would reveal the extent to which these factors pertain.)

Based on recent historical data, the amount of arable land in Trinidad and Tobago is hardly increasing at all (3.4% increase from 1980 to 1990), despite rapid destruction of natural forest. There is certainly a pressing need for additional arable land, in view of the substantial importing of cereals over a long period (Reference 1: 252,000 metric tons in 1980 and 246,000 metric tons in 1992), and a stagnation in food production per capita (Reference 1: -.1%/year for 1979-92). Fertilizer inputs are and have been high (Reference 4: 66 kg per ha in 1979-81 and 67 kg/ha in 1989-91), and yields are relatively high (Reference 4: 2,833 kg of cereals per ha in 1990-92). The fact that the amount of arable land has not increased in the face of long-term high-level cereal imports and substantial destruction of natural forests suggests that the amount of available land will not increase in the future.

It may be reasonably hypothesized that the historical high level of deforestation is a major factor underlying the fact that the amount of arable land has remained essentially constant, in spite of high population growth. In view of this, it may reasonably be conjectured that the amount of arable land will decrease, once the natural forests are completely destroyed (in order to provide living space for the increasing population).

In view of the experience over the past decade, in which the amount of arable land has not increased despite high demand for food and extensive destruction of natural forest, it appears reasonable to expect that the amount of arable land will remain constant at 1,200 square kilometers until all of the natural forest is destroyed, and will decrease thereafter.

Note that some portion of the deforested land may become available for use as arable land. While some deforested land may indeed be used for crops, the net increase in arable land over the period 1980-90 (i.e., arable land increases less arable land decreases) was only 3.4%, or .335% per year. This corresponds to just 4 km² per year, or about 10% of the amount of deforested land.

In view of the preceding considerations, a reasonable assumption concerning the future availability of arable land (in the near future) is that (1) it will remain essentially constant as long as the population continues to grow and the current rapid destruction of natural forests continues; and (2) if deforestation ceases (either because of the complete destruction of the forests or other factors), the arable land will decrease by an amount proportional to the amount of population increase.

Because the destruction of forest has continued at a high rate for a long time, it will be assumed that this destruction continues (at the same amount per year). At the end of 40 years, the forest will be gone. Currently, the population is increasing at 1.1% per year (Reference 2), or about 14,300 per year, and the forest is being destroyed at a rate of 37 square kilometers (3,700 ha) per year. This corresponds to a loss of .26 hectares of agricultural land per unit increase in population.

An issue to address is the rate at which arable land will be destroyed after the forest destruction is complete. During recent decades, the population has grown at the annual rate of 1.1-1.3% per year (Reference 3). During this period the amount of arable land has remained about the same, and the amount of forested land has decreased by about 1.9% per year. During the period in which the forest has decreased by 1.9% per year and the population has grown by about 1.2% per year, the change in the non-arable, non-forest area has been about 1.7% per year. This is shown in the following table (areas in square kilometers):

Total Forested Arable Other Other Land

Year Land Area Land Area Land Area Land Area Area (%)

1980 5,128 1,920 1,200 2,008 .39

1990 5,128 1,550 1,200 2,378 .46

The change from 2,008 to 2,378 over a ten-year period is an annual (compound) growth rate of 1.7%. During this period, the economy of Trinidad and Tobago has been relatively stagnant, so that the loss of agricultural (arable + forested) land area cannot reasonably be attributed solely to or even mainly to economic pressure. Rather, a significant portion of the loss would appear to be associated simply with the physical requirement for living space for the additional population (housing, roads, businesses, government, schools, and other infrastructure).

The average annual loss of agricultural land is about 37 km² per year. At an annual growth rate of 1.1% (net of migration), the population of 1.3 million is increasing by about 14,300 per year. As noted, this corresponds to an annual loss of .26 ha per person (37x100/14300) for living space.

In the absence of a thorough analysis of detailed and comprehensive data on the subject, it is not possible to predict with a high degree of certainty what changes will occur in the amount of arable land in the future. If the population continues to grow at current rates, it seems likely that it will remain somewhat unchanged for the near future (while forests remain), and then decrease (after the forests are gone). For the arable-land projections used in this report, it will be assumed that the amount of arable land will increase by 10% of the deforested area (3.7 km²) per year until the forests are totally destroyed, and that the amount of arable land will decrease at 1.7% per year thereafter, as long as population growth continues at current levels. This assumption corresponds to the assumption that recent trends in population growth and deforestation continue as in the recent past.

This assumption is somewhat optimistic in one sense, since it ignores the long-term loss of agricultural productivity (soil depletion) of the land. (In most countries of the world, cropland is being depleted much more rapidly than it is being replenished.) More importantly, it ignores the fact that population growth cannot continue at any positive rate indefinitely. At some point, the population would cover the entire land area. With Trinidad and Tobago's current large population and high growth rate, the period of rapid continuing positive population growth is nearing an end. While current growth rates could continue for a few decades more, the environmental changes associated with such growth would be massive. Trinidad and Tobago's current agricultural resources are barely sufficient for its current population, and the nation relies heavily on food imports. Over the next several decades, the cost of food imports is expected to rise dramatically, as world fossil fuel supplies dwindle and world population soars. In terms of gross national product (Reference 1: USD3,940 in 1992, compared to US = USD23,240), Trinidad and Tobago ranks 100 out of 132. In terms of purchasing power parity per capita, Trinidad and Tobago's rating is 40 (where US corresponds to 100) (also Reference 1). At this economic level, Trinidad and Tobago will find it increasingly difficult to purchase food on the world market.

In summary, it is unreasonable to project either that Trinidad and Tobago's population will continue to grow indefinitely, or that its arable land will totally disappear. More reasonable projections would be based on a "systems" model that takes into account the interrelationships among population, the environment, and the economy, not on extrapolation of current trends. While present trends cannot continue indefinitely, they may continue for some time, and indeed to the point at which massive environmental changes occur -- this has already happened in many countries around the globe. Extrapolation of current trends is useful not for making reliable estimates of actual levels at times far in the future, but for showing the environmental implications of continuing current behavior and practices.

Figure 1 illustrates recent levels of Trinidad and Tobago's agricultural land (arable and forested). The figure plots the data described above, and graphically depicts the negative association between population growth and reduction in agricultural land area.

Figure 2 illustrates the projection of arable and forested land area in Trinidad and Tobago, under the assumptions discussed above.

Neither Figure 1 nor Figure 2 place the current and projected levels of arable and forested land in historical perspective. In studies dealing with population, changes occur very slowly, generally on the order of a few percentage points per year. At such low rates of change, it is not easy to grasp the magnitude of the changes that are occurring over long periods of time, or to assess the reasonableness of the projections from a macroscopic point of view. To look at Figure 1, for example, the rate of change of both population and forested area is hardly noticeable. To place the data of Figure 1 and Figure 2 in a better perspective, they are plotted in Figure 3, which covers a much longer time period.

A problem that arose with respect to Figure 3 is that data were not available to this report on historical arable-land and forested-land areas prior to 1980. To enable the construction of a tentative version of Figure 3 (pending access to historical data), the historical levels of arable-land and forested-land were conjectured. Several hundred years ago, most of the land area was forested, and the amount of arable land was probably on the order of 100 km² until about 1800. From 1800 to the present era, the amount of arable land increased to its present 1,200 km². In recent times, deforestation has been occurring at an average rate of about 37 km² per year. Combining these features (by extrapolation, interpolation, and smoothing) results in the graph presented in Figure 3. This graph illustrates dramatically the impact that human population has had in changing the nature of the land area of Trinidad and Tobago, and that the nation is in the final stages of destroying its natural forest.

IV. Projection of Carrying Capacity

While the amount of arable land is a major factor determining agricultural output, the productivity of the land is just as important. The agricultural productivity of land depends on many factors, including availability of water, natural productivity, climate, fertilizer, pesticides, energy, variety, and capital equipment. With respect to impact on the environment, the essential factor is the carrying capacity of the land -- the number of persons that the land can feed. This factor may be measured as number of persons who can be supported per hectare of arable land, or the maximal arable-land population density. This number is affected greatly by the type of food consumed -- the "trophic level" of the consumption. As population grows to the limit of the food supply, efficiency is increased by increasing consumption at a low trophic level, such as by eating more cereal grains and less meat.

We shall refer to the maximal arable-land population density of land when used at a low tropic level of consumption (i.e., use of arable land for cereal production rather than meat production) as the "productivity" of the land. With a high level of energy inputs, the productivity of arable land is high, e.g., 10 persons per hectare. With low inputs, the productivity is much lower, e.g., 2.5 persons per hectare.

Apart from the trophic level of consumption, the main factor influencing arable-land productivity is the level of energy inputs to agriculture. The term "energy inputs" includes all energy-related inputs, including fertilizer, pesticides, irrigation, biological inputs (e.g., high-yield varieties) and mechanization (both equipment and fuel). In order to project the arable-land productivity, and hence the carrying capacity of the land, it is necessary to examine and project the availability of energy inputs to agriculture in Trinidad and Tobago over the next several decades.

As long as world fossil fuel supplies last, a strong economy can purchase sufficient inputs to produce a high level of productivity. As oil and natural gas reserves deplete over the next 50 years and world population growth continues, the cost of energy inputs will skyrocket, and few countries will be able to afford to purchase these inputs. At that time, the land productivity will drop to pre-industrial levels for most nations without domestic coal reserves. Trinidad and Tobago has not realized economic growth in recent years: Reference 4 reports an average annual growth rate of -3.9% in gross national product for the period 1980-91 and an average annual growth rate of -4.4% in gross domestic product over the same period.

Trinidad and Tobago's domestic energy reserves consist of 80 million metric tons of crude oil and 252 billion cubic meters of natural gas (Reference 4). Its current commercial energy production is 533 petajoules (PJ, or 10¹⁵ joules). Its annual commercial energy consumption is 296 PJ. The conversion rate for oil and gas to petajoules is 1 million metric tons of oil = 41.87 PJ and 1 billion cubic meters of natural gas = 38.84 PJ. Converting the physical reserves to petajoules yields 3,350 PJ of coal and 9,788 PJ of natural gas, for a total of 13,138 PJ.

As a percentage of consumption, exports are 76%, or 225 PJ. At current production rates, Trinidad and Tobago's energy reserves will last 13,138/533 = 24.6 years. If production is increased, either because of an increase in domestic consumption or exports or both, the years of production will decrease.

Per capita energy consumption in 1991 was 237 gigajoules (GJ) (Reference 4) versus 320 GJ for the US in the same year. If Trinidadian per capita consumption were to rise to the 320 GJ per capita level, an additional total of (320-237) x 1.3 million = 107,900,000 GJ, or 107 PJ would be consumed annually, if the population remained constant at 1.3 million. This amount is equivalent to about half the current export amount (225 PJ). If the population were to double, all of the export amount would be consumed domestically, i.e., the total commercial energy production would be consumed domestically. If domestic per capita consumption were to rise to 320 GJ per capita, the total domestic consumption would be 1.3(320) = 416 PJ, if the population remained at 1.3 million. If exports were held constant at 225 PJ and domestic per-capita consumption were to rise to 320 GJ per capita, the total annual production would rise to 225 + 416 = 641 PJ. At that rate of production, proven reserves would last only 13,138/641 = 20.5 years. If the population were to double, this length of time would decrease correspondingly. If exports were to increase (e.g., to pay for more food imports at higher prices), the length of time would shorten even more.

In the long run, demand for energy will rise (as fossil fuel reserves deplete), so that demands for exported oil and gas will rise. Currently, Trinidad and Tobago's economy is heavily industrial (Reference 1: 3% of gross domestic product (GDP) in agriculture, 36% in industry, 8% in manufacturing, and 61% in services for 1992, vs. US figures of 2%, 33%, 22% and 65% for 1988, reported in World Development Report, 1990). In 1990, only 7% of the total labor force was agricultural (Reference 4). According to Reference 4, in 1989-91 Trinidad and Tobago imported 254,000 metric tons of cereals, up from 237,000 metric tons of cereals in 1971. In the 1990-92 period it produced only 17,000 metric tons of cereals.

As the preceding computations show, Trinidad and Tobago's proven energy reserves will not last much longer. At that point in time, whatever food (or agricultural inputs to food production) is purchased on the world market will no longer be purchased using foreign exchange earnings from energy exports, since there won't be any. Since Trinidad and Tobago's economy has not grown at the same rate as the population in recent years, and food imports are rising, an important issue to be addressed is how the economy will generate foreign exchange earnings to pay for food imports (or agricultural inputs to its domestic agriculture sector) after domestic energy reserves exhaust.

The implication of these figures is that as Trinidad and Tobago's energy reserves decline, it will, if current trends continue, rather soon reach the point at which it has neither the domestic agricultural capacity to feed its population nor the economic wherewithal to purchase food on the world market. As this situation evolves, the pressure on the land and environment will become severe.

As world oil and gas reserves deplete, the cost of energy inputs to agriculture will soar. As Trinidad and Tobago's own reserves deplete, the nation will transition from an era of high-energy-input agriculture to low- (traditional-) energy-input agriculture. Yields under high-energy-input (HEI) agriculture (fertilizer, pesticides, irrigation, biotechnology, mechanization) are high. At a low trophic level of consumption (i.e., consumption of cereals rather than meat), the maximal arable-land productivity can be about 10 persons per hectare. Yields under low-energy-input (LEI) agriculture are substantially less -- often 10-50% as much. We shall assume that the current arable-land productivity in Trinidad and Tobago with high-energy inputs and a low-trophic level consumption is 10 persons per hectare.

Although it is expected that productivity will decrease in the long run (i.e., over the next 50 years), the rate at which this decrease occurs is subject to conjecture. In recent years, Trinidad and Tobago's agricultural production has decreased on an exchange-rate basis (Reference 1: 6.6% annual decline over the period 1980-92) at twice the rate of gross domestic product (-3.7% over the same period). Although total agricultural production and food production have declined by about 5% on a per-capita basis (Reference 4) over the period 1981-1991, total agricultural production and food production have increased by about 8% over that period (recall that cropland increased by 3.4% over this period). Average yields of cereal production (kg/ha) have decreased by 9% over the same period, and average yields of roots and tubers have increased by 14%.

These figures do not suggest that Trinidad and Tobago's arable-land productivity is currently in the midst of a general decline. In view of the mixed picture, it is reasonable to assume that maximal arable-land productivity will continue at a level of 10 persons per hectare for some portion of the next 50-year period, and then decline to a lower level, e.g., 2.5-5 persons per hectare.

It is acknowledged that assumptions on the timing of the decline of maximal arable-land productivity as energy resources deplete is somewhat conjectural. What is far less speculative, however, is the fact that the world's oil and gas reserves are rapidly being depleted, and it is generally recognized that known global reserves will be depleted within about 50 years at current consumption rates (Reference 4: 45 years for oil, 52 years for natural gas). And, it is a fact that agricultural yields for low-energy-input agriculture are but a fraction of those of high-energy-input agriculture.

With a high level of agricultural inputs, Trinidad and Tobago has arable land resources capable of feeding a substantial proportion of its current population. As the price of agricultural inputs rises, however, the use of productivity-enhancing inputs will decline, resulting in a corresponding decline in the capacity to produce food from domestic arable-land resources. As the population continues to grow, the nation will face an ever-widening gap between food needs and food production and food purchasing capacity.

Because of the uncertainty over both the magnitude and the timing of the decline in maximal arable-land productivity, three different cases will be considered. The three assumptions correspond to different "paths" (curves) from the current maximal arable-land productivity to the eventual arable-land productivity. Specifically, it will be assumed that maximal productivity continues at a level of 10 persons per hectare for 10 years, for 20 years, and for 30 years, before declining to a lower level. Furthermore, three levels will be assumed for the lower level: 10 persons per hectare (i.e., no change), 5 persons per hectare, and 2.5 persons per hectare. Although the assumption of an eventual level of 10 persons per hectare is not considered reasonable, it is nevertheless included to show that the general conclusions reached in this analysis are not dependent on the particular productivity level assumed. (Note: The conclusions of this report are not affected by the assumed level of productivity in 50 years; in all cases, the gap between population and population carrying capacity is large and continues to widen.)

Figure 4 shows the projections of population carrying capacity under the preceding assumptions about the availability of arable land and the productivity of the land. In the Figure, "Alternative 1" refers to the assumption of constant productivity at a level of 10 persons per hectare for 10 years followed by a decline to 2.5 persons per hectare in 2045; "Alternative 2" refers to the assumption of constant productivity at 10 persons per hectare for 20 years followed by a decline to 5 persons per hectare in 2045; and "Alternative 3" refers to the assumption of constant productivity of 10 persons per hectare throughout the period 1995-2045.

V. Projection of Population

Historical Population of Trinidad and Tobago

Figure 5 shows the historical population of Trinidad and Tobago. The Figure graphically illustrates the explosive population growth of the nation in recent times, with the population growth in the past 50 years is approximately equal to the growth in all preceding history.

Exponential growth of the type that has continued in Trinidad and Tobago for the past several decades cannot continue indefinitely. At current growth rates, Trinidad and Tobago's population is doubling in less than fifty years. At the rate at which the island nation's land resources are being consumed, the growth will cease before long. The nation's response to the situation will determine whether the cessation of growth is orderly or catastrophic, and whether it occurs before or after the natural environment is completely destroyed.

The data in Figure 5 are from several sources. The early historical data are from Bridget Brereton's book, A History of Modern Trinidad, 1783-1962 (Reference 7), and most of the later historical data are from the Atlas of World Population History (Reference 8). The most recent data are from United Nations or related sources.

The following table presents the data plotted in Figure 5.

Year Population Source

1498 20,000-40,000 Brereton (Ref. 7)

1592 15,000-20,000 Brereton

1765 2,503 Brereton

1784 6,503 Brereton

1797 17,718 Brereton

1800 20,000 Atlas of World Population History (Ref. 8)

1850 80,000 Atlas of World Population History

1900 270,000 Atlas of World Population History

1925 380,000 Atlas of World Population History

1950 630,000 Atlas of World Population History

1950* 640,000 World Resources Institute (Ref. 4)

1975 1,100,000 Atlas of World Population History

1990 1,240,000 World Resources Institute

1990* 1,236,000 The Population Council (Ref. 3)

1992 1,300,000 The World Bank (Ref. 1)

1995 1,310,000 World Resources Institute

1995* 1,305,000 The Population Council

For the cases in which multiple figures are available, the asterisked ones are plotted in Figure 5. These figures were selected because they are of highest precision (greatest number of significant digits).

Population Projections -- No Resource Constraints

Population projections for Trinidad and Tobago are available from several sources, including the World Bank (Reference 1) and United Nations (References 2, 3, and 4). These projections are made under assumptions about the demographic characteristics of the population in the future. The most important assumption concerns the total fertility rate (TFR), or average total number of children that a cohort of women will have during their lifetime. It is the expected number of births that 1,000 women would have if they experienced a particular set of age-specific birth rates throughout their reproductive span (equal to the average number of children born to a women in her lifetime in a stable population). It is usually specified on a per-woman basis, e.g., 2.7 children per woman.

Most population projections are based on very simple assumptions about future total fertility rates and the values of other demographic parameters, such as the assumption that the TFR will decline steadily to a "replacement" level (value of about 2.1 for healthy populations) and stay at that value thereafter.

The following table presents several population projections for Trinidad and Tobago, under this assumption. Standard World Bank and United Nations (UN) sources present projections to the year 2025; Appendix A generates a projection to the year 2045. The projections specified below for the period 1995-2025 are from the United Nations Population Division, reported by the World Resources Institute (Reference 4).

2000* 1,365,000 The Population Council

2000 1,000,000 The World Bank (rounded to nearest million)

2025* 1,780,000 World Resources Institute

2025 1,800,000 United Nations Population Fund (Ref. 2)

2025 2,000,000 The World Bank (rounded to nearest million)

2045* 2,006,000 Appendix A of this report

In the figures that follow, the asterisked figures will be plotted, because they are of similar precision (they are all based on similar demographic assumptions).

Each of the preceding population projections is based on a single assumption about the values of all demographic parameters that affect population growth. Because of the uncertainty associated with assumptions about the future values of demographic parameters, however, it is usual to make projections under a range of values of key parameters. The UN, for example, publishes three global population projections -- the high, medium, and low "variants". The populations given above correspond to the low variant.

Population projections are quite sensitive to the assumptions made about future demographic parameter values, especially total fertility rates and migration rates. Seemingly small changes in the values of these parameters can result in quite sizable differences in the projection after a few years. Because of the high level of sensitivity of population projections to the assumed values of the demographic parameters, it is desirable to perform a "sensitivity analysis," in which projections are made under a range of values for the most important parameters.

Appendix A presents population projections for Trinidad and Tobago under three different sets of assumptions about the values of demographic parameters affecting population growth (fertility rates, mortality rates, and migration rates). For an island nation such as Trinidad, a factor that is every bit as important as the TFR is the emigration rate. The three population projections for Trinidad and Tobago correspond to alternative assumptions about the TFR and the emigration rate. The following table summarizes these assumptions (additional details are provided in Appendix A).

Total

Projection/ Fertility Emigration

Assumption Set Rate (TFR) Rate

I 2.5-2.4 10,000/year

II 2.5-2.3 5,000/year

III 2.5-2.1 0/year

The third projection listed above (TFR declining to 2.1, zero emigration) corresponds most closely to the UN "low variant" projection. The other two projections assume that a substantial emigration occurs. If little emigration occurs and the TFR does not decline rapidly to 2.1, the projected population would be substantially larger than the highest projection listed above (i.e., Projection III). Such projections would correspond more closely to the UN medium and high variant cases. (Note: Emigration can keep the rate of growth substantially less than the natural rate of increase. As the global population expands rapidly in the coming years, immigration may be a major factor in determining a particular country's population. Since immigration has a net value of zero for the world, it is not a factor in projections of the global population. For this reason, although much study has been conducted by international organizations on total fertility rate, its determinants, and its trends, relatively little attention has been paid to immigration. For Trinidad and Tobago, however, immigration can be (as evidenced by the nation's history) as important a factor as total fertility rate. The preceding assumption sets consider three rather arbitrarily specified levels of emigration for Trinidad and Tobago. Because of its substantial impact on the nation's population, the topic of immigration warrants further study.)

Figure 6 displays these three population projections.

Appendix A presents a rationale for selecting the preceding values as a basis for the projections. The projections resulting from the three sets of values presented above are not the highest nor the lowest projections that could be obtained by assuming various combinations of reasonable values for the key parameters, but they do indicate a range in which population projections are likely to fall under reasonable assumptions.