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U.S. Immigration

and the Environment:

Scientific Research

and Analytic Issues

Ellen Percy Kraly, Ph.D.

Department of Geography

Colgate University

February 1995

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Contents

Executive Summary -5-

Introduction -15-

A Further Rationale -16-

Perspectives on the Role of Migration in

Population- Environment Dynamics -20-

Introduction -20-

Population-Environment Models and Migration -22-

Migration and Global Environmental Change- 26-

Perspectives on U.S. Immigration and the Environment -26-

Conceptual Issues Emerging from Models of Population- Environmental Change -27- Immigration as a Component of Population Growth -28-

Geographic Scale and Temporal Specification -29- Spatial, Sectoral and Temporal Linkages -32-

Implications for Theoretical Research on U.S. Immigration and the Environment -35- Recommendations for Theoretical Research -35-

Empirical Research concerning Migration and

Environmental Processes and Change -36-

Introduction -36-

Research on Regional and Local Population-Environmental Dynamics -38-

Research on Environmental Outcomes -42-

Urbanization and Environmental Issues -44-

Research on Immigration and the Environment in Australia -45-

Implications for Empirical Research on the Relationship between U.S. Immigration

and the Environment -47-

Recommendations for Empirical Research -48-

Methodologies for Assessing the Environmental

Consequences of U.S. Immigration -49-

Introduction -49-

Environmental Impact Assessment -50-

Population-Environment Monitoring Systems -56-

Relevance of Methodologies for Analysis of Immigration and Environment -57- Recommendations for Research on Methodologies -59-

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Information Requirements for Studying the Environmental

Consequences of U.S. Immigration -60-

Introduction -60-

Conceptual Issues -62-

Closure in Demographic Accounts -65-

Availability of Data for Regional and Local Analysis -66-

Implications for Research on U.S. Statistical Information concerning Population Immigration and the Environment -67-

Recommendations for Improvements in Data -67-

Conclusions -71-

A Final Observation -73-

References -74-

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EXECUTIVE SUMMARY

Each of the most recent major amendments to the Immigration and Nationality Act includes a requirement for the federal government to assess the environmental impact of alien immigration on the United States. Specifically, the Immigration Reform and Control Act of 1986 [IRCA] specifies that the Triennial Report to Congress shall provide a

". . . description of the impact of immigration on environmental quality and resources . . ." (Sec.401(b)(3)). The Immigration Act of 1990 gives the Commission on Legal Immigration Reform the mandate to consider the ". . . social, demographic and natural resources impact of immigration . . ." (Sec.141(c)(1)(C)).

The goal of this report is to contribute to this area of policy analysis by reviewing existing scientific literature concerning immigration and environment, to identify research issues emerging from extant scholarship, and to develop recommendations for areas of needed research that will benefit the immigration policy process. It is important to note at the outset that remarkably little hard evidence exists about the environmental effects of alien migration on the United States. A great deal of speculation exists about the

nature of the relationship and there is increasing popular commentary about the degree to which immigration is associated with environmental problems in local areas as well as in the nation as a whole. The direct or causal effects of U.S. immigration on the environment have not been established, however, through scientific study. Moreover, there are significant limitations in U.S. statistics on immigration and population for the study of environmental impacts.

The report is organized around four

dimensions of the research process that

are relevant for examining the relationship between U.S. immigration and environmental issues. First, the section,

Perspectives on the Role of Migration in Population-Environment Dynamics, considers the relevance of theories of population and environmental change for the study of immigration and its effects. Second, the section, Empirical Research Concerning Migration and the Environment, reviews the results of research relevant for the study of immigration and

environment. Third, the section, Methodologies for Assessing the Environmental Consequences of U.S. Immigration, briefly reviews selected approaches to measuring environmental impact. Fourth, the section, Information Requirements for Studying the Environmental Consequences of U.S.

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contested: uses of the model focus primarily on the increase in population size without specification of the different sources of population growth, for example natural increase (births minus deaths) relative to net migration.

Theories on population and environment vary in assumptions about the relative importance and direction of the effect of each of the factors (P,A,T) as well as the significance of interrelationships among the factors. Neo-Malthusian perspectives emphasize the significant influence of population growth for environmental impact and conceptualize a negative relationship between population growth and the availability and, increasingly, the quality of environmental resources. In constrast, more "optimistic" perspectives emphasize the enhanced potential inherent in positive population growth for social, economic, and technological progress, and hence, the means to solve environmental problems. Primary importance is given to changes in technology and social and economic organization in mitigating the effects of the other two factors. A third approach conceptualizes population pressure and short-run negative effects as a stimulus to technological innovation and more effective use of resources.

Immigration, outlines strengths and weaknesses of the federal statistical system for analyses of the role of immigration in population and environmental change. Recommendations for needed research are presented at the end of each section. The Conclusions section reviews research issues and priorities within the context of a national program of research on U.S. immigration and environment.

Perspectives on the

Role of Migration in Population-Environment Dynamics

The general model of environmental impact identifies three broad sets of factors influencing environmental change: Environmental impact [I] is conceptualized as a function of population characteristics [P], patterns of consumption [A, for affluence] and technology [T], the use and manipulation of energy and other natural resources. While this model has provided an organizing framework for much of the debate concerning population and the environment, it has also been criticized for incomplete conceptualization of the components and lack of grounding in social scientific theory. The degree to which the population concept is well specified or connected to theory is also

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Perspectives thus vary in the degree to which population is proportional to environmental change. According to the demographer Keyfitz:

If all else is equal, action damaging the environment is directly proportional to the number of people. That at least seems the most appropriate initial hypothesis. . . . The burden of proof is one anyone who argues against the proportionality hypothesis in either way. (Keyfitz 1993: 547)

In thinking about the impact of alien immigration on the U.S. environment, relevant questions center on the degree to which the impact of alien migration is proportionally less than, greater than, or equal to the number of immigrants.

Not surprisingly, different theoretical perspectives lead to different conclusions about the national and regional environmental impacts of U.S. immigration. Some economists have emphasized the potential contributions to human capital and the potential for technological innovation deriving from positive population growth in the United States and from alien immigration. Many ecologists, in contrast, highlight the role of alien immigration in U.S. population growth with

its negative environmental consequences and often focus on the contribution to future growth resulting from the descendants of current immigrant streams.

In addition to the need to specify more clearly the role of migration in theories of population and environment, several additional issues emerge from the review of theory. Both geographic level and temporal frame of analysis must be specified in theoretical models and ultimately in empirical research. The effects of immigration on environmental processes may be expected to be significantly different for metropolitan areas, rural communities, states, and in the short-term versus the long-term. A third issue is the importance of understanding linkages or connections among geographic areas, economic sectors, and through time. For example, the concentration of immigration in certain metropolitan areas in the United States may have environmental consequences for areas and natural

resources geographically removed from the cities.

The most fundamental recommendation for theory development is to revise models of population and environment to break population growth into its component parts in order to consider more clearly the effects of migration. Of par-

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problems, or on the environmental outcomes of interest, such as land use patterns and urban sprawl, water supplies and quality. Social demographic research is being conducted concerning the role of alien immigration in metropolitan and regional growth patterns in the United States. Inferences about environmental impacts resulting from alien migration are often drawn without direct measurement of the relationships between the two sets of factors: patterns of population growth and immigration are observed to co-vary with environmental outcomes, while data on causal relationships are not presented. Similarly, environmental research often focuses on direct measurement of environmental processes and quality with only cursory measurement of population and social processes that are set out in the introductory statements as direct causes of environmental change.

In short, there exists very little direct causal analysis of relationships among population, immigration, and environment in the United States. Virtually no research has been conducted on the role of immigration status or nativity in the analysis of consumption and production, such as differential patterns of energy consumption, commuting and land

use patterns, and water conservation

practices.

ticular relevance for the United States, moreover, is the specification of effects for different types of international population movements, including permanent resettlement, refugee migration, temporary labor migration, and tourism, within theories of environmental impact.

Empirical Research Concerning Migration and the Environment

There is a strong and long tradition of research on the consequences of immigration for U.S. society, economy, and polity. Scholarly interest in the environmental consequences of U.S. immigration has a relatively more recent history, originating in the late 1960s with environmental concern over national population growth and the role of annual alien

immigration in the path to population stabilization.

There is increasing interest among scientists and policymakers in the environmental implications of immigration for states, metropolitan areas, and local communities in the United States. Most research to date, however, tends to focus either on population growth and trends in alien immigration, viewed as the causes of environmental change and

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Probably the best research on migration and environmental outcome has been conducted in areas of the developing world. Very often these are case studies of the complex relationships among migration, social, economic and technological change and environmental processes. These studies may serve to inform conceptual models, research design, and measurement in empirical studies of population, migration, and the environment in the United States.

The general observation concerning the status of empirical research on U.S. immigration and the environment is the need for more of it. There is critical need for the initiation of well-designed studies that will yield both descriptive information concerning trends and patterns of demographic and environmental processes in U.S. states and local areas, as well as causal analyses of the relationships between types of alien immigration and environmental impacts. It is particularly important that research on the environmental effects of immigration identify different sources of alien migration, for example, permanent resident aliens, foreign students and workers, and tourists. This significance of subsequent internal migration among immigrants should also be studied.

Methodologies for Assessing the Environmental Consequences of

U.S. Immigration

Two frameworks that have been developed to study environmental change

are relevant for the study of U.S. immigration and the environment: environmental impact assessment [EIA] and population-environment monitoring systems [PEMS]. Environmental impact assessment most often attempts to forecast the impacts of development projects or structural or engineering initiatives, generally new activities within a geographic area. Monitoring systems represent ongoing social and environmental accounting frameworks for the collection and analysis of data over time for specific geographic areas.

The goal of the EIA process is the provision of objective, typically quantifiable, information for policymakers and program administrators concerning the range of environmental consequences of some proposal, often a building project, for a region or place. Inherent in the EIA process are theoretical models of the nature of causes of environmental change. It is important to place the proposed source of environmental change, i.e., the project or policy initiative, within

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a multivariate framework in which all exogenous influences on environmental outcomes are documented. The process of EIA involves predictive and, thus, causal analysis. The approach may be useful in assessing various immigration policy options, for example, changes in overall levels of annual alien immigration to the United States, as well as changes in the structure of immigrant admissions in terms of individual and family characteristics.

Population-environment monitoring systems measure changes in these factors over time and are useful in providing an empirical foundation for evaluation of existing policies and collecting baseline data for identifying subsequent environmental impacts. If the approaches to monitoring are standardized across administrative units, results of PEMS can be compared among local areas and also aggregated for analysis of regional dimensions of national policies. This characteristic of PEMS is critically salient for purposes of U.S. immigration policy evaluation.

A critical issue in exploring the use of EIA or PEMS for the study of immigration and environment is the degree to which the assessment or monitoring system documents all significant dimensions

of environmental impact for the regions. Beyond the contribution of alien immigration to population growth for a

region or area are issues concerning

patterns of resource consumption, technological innovation, conservation behaviors, land use patterns, and how these vary between immigrants and U.S. residents, and among types of immigrants. Moreover, the methodologies must be open to document other sources of environmental impact for the study area, such as in- and out-migration of U.S. residents and economic change. Finally, the relevance of any EIA, monitoring system, or other more appropriate research design for determining the effect of U.S. immigration on the environment will rest, finally, in the degree to which national, state, and local data collection systems can support multivariate analysis of complex dimensions—demographic, economic,

institutional, behavioral—of environment change.

Information Requirements for Studying the Environmental Consequences of

U.S. Immigration

The specification of data needs should be guided both by theory and by the

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important policy questions concerning U.S. immigration and the environment. While the emphasis of this report is generally on the relevant research concerning immigration, it is important to note the serious concern among environmental scientists about the status of environmental data for the United States and the capacity for monitoring environmental quality and resources for different geographic areas.

Fundamental to the analysis of immigration and the environment, however, is statistical information on the contribution of alien immigration to population growth for states, regions, cities, and local communities in the United States. Further, because the present policy

debate concerns the impact of alien migration, disaggregation of the components of population growth—fertility, mortality, and migration—by immigration status is also a necessary characteristic of statistical information. Accordingly, the report focuses on the adequacy of U.S. data on population processes for measuring the role of alien immigration in population dynamics on national, regional, and local scales of analysis.

Problems in the adequacy of national demographic accounts for the comprehensive measurement of trends and com

ponents of population change have been well documented. Three sets of issues pose particular problems for the empirical evaluation of the role of alien

immigration in population growth and generally in environmental processes. First, conceptual problems exist in official data on alien immigration. U.S. statistics on immigration collected by the U.S. Immigration and Naturalization Service [INS] represent legal and administrative categories, including permanent resident alien, nonimmigrant, refugee, asylee, and parolee. As a result these data are less than ideal measures of demographic concepts of long and short-term immigration that use criteria such as length of stay and activity in the country. Work has been done to manipulate INS administrative data better to represent demographic concepts of alien immigration. Comparison of demographic measures with official INS data on admissions yields important differences in the national origins characteristics of annual alien immigration to regions and states in the United States.

Second, U.S. statistics on international migration lack closure: it is not possible to assess the impact of alien immigration on population growth in an area if not all sources of population change are known. For example, no systematic

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source of data exists on the process of out-migration of aliens or citizens from the United States; measurement of levels and patterns of undocumented migration relies on demographic estimation. Very useful work has been conducted by the U.S. Census Bureau to estimate emigration using census and survey data. There has also been consideration of other federal sources of administrative data as a basis for estimating emigration. As with alien emigration, estimates of undocumented migration have been developed using methods of demographic estimation for U.S. census data, immigrant data records, and assumptions about mortality levels, emigration, and census undercount. Demographers at INS

have also estimated the size of the

undocumented alien population by state of residence.

Third, the role of alien migration in annual population growth for states and local areas is not easily measured. Decennial census data are extremely valuable for measuring components of population change for small geographic areas at ten-year intervals. Currently, however, annual measures of the immigrant population at the subnational level are available for large states and metropolitan areas through the Current Population Survey. The lack of data on internal

migration patterns of immigrants is particularly frustrating for comprehensive study of the effect of immigration on states and local areas.

Longitudinal survey design holds strong potential as a means more effectively to collect data on the social demographic behavior and experiences of immigrants and U.S. citizens relevant for the study of immigration and environment. The research community has recognized the value of a survey of immigrants to directly study patterns of settlement and internal mobility among immigrants, as well as social characteristics and economic behavior among immigrant cohorts and how these change over time. To yield results appropriate to environmental research, survey design must address, first, the need for reliable data at different geographic scales, and, second, the critical need to compare environmental relevant behaviors and characteristics among different groups

of immigrants and with U.S. citizens

over time.

Conclusions

Four broad areas of recommendations for scientific research concerning U.S. immigration and environment emerge from this review:

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First, research on the environmental consequences of U.S. immigration will benefit from the revision of models of the population-environment to specify the role of migration and, specifically, types of international migration, in processes of environmental change. Theoretical development concerning migration and the environment needs to occur to derive relevant and testable hypotheses about causal relationships and effects.

Second, research on U.S. immigration and the environment should provide both descriptive results concerning trends in demographic and environmental change at different geographic scales and for specific places, as well as causal insights about the nature of relationships between levels and types of alien immigration and environmental outcomes. Studies should be undertaken on the national, regional, and local levels to compare the effects of immigration at different geographic levels, adding to our understanding of geographic variation of impacts.

Third, it is critical that attention be given to developing the necessary research designs for ongoing study of the interrelationships among population, immigration, and environmental processes for the nation, states, and local areas in the United States. Survey methodology has

been shown to hold useful potential for studies of the social and economic consequences of migration and should be explored for studying environmental impacts.

Fourth, the statistical foundation for the analysis of the environmental consequences of U.S. immigration must be strengthened. Migration statistics—data on alien immigration, internal migration, and emigration—must be improved to accommodate local and regional analysis for intercensal periods. As relevant in these times of fiscal restraint in federal spending is the critical need to advocate the continuation and maintenance of current statistical programs: INS statistics on the admission of aliens to the United States must continue to be collected and made accessible for public use; questions concerning nativity, citizenship, and geographic mobility must continue to be asked on the decennial census and the Current Population Survey. Finally, an assessment of the status of indicators of environmental quality and resource availability is a critical component of developing an agenda of policy relevant scientific research.

These broad recommendations beg the question of strategy for stimulating and organizing research efforts to address the

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important analytic issues concerning U.S. immigration and the environment. Interdisciplinary collaboration is essential for the development of a research program on U.S. immigration and the environment. Interaction among environmental and social scientists in government agencies and planning offices, as well as in universities and research institutes, must be encouraged to initiate theoretical development, to reflect on research design, to document the status of available data, and, ultimately, to establish a framework for interpretation of research results in connection to the policy process.

Given the need for both baseline documentation and exploratory analytic research, it seems highly appropriate to initiate a coordinated research program on immigration and environment for specific regions, metropolitan areas, and local communities in the United States. Selected places should be identified as research sites in which an integrated program of population and environmental research would be implemented. Interdisciplinary collaboration among scientists must be organized within research sites and coordinated with relevant planning and scientific agencies at the federal, state, and local areas.

A Final Observation

Barry Commoner once stated that he knew ". . . of no scientific principle which can tell us how much to rely on population control and how much on technological change (and the required economic controls) in order to reduce environmental impact. The choice between these alternative paths is clearly a political one, not a matter of science." A somewhat contrasting perspective is evident in this report. Research on relationships between U.S. immigration and the environment is an essential component of rational and responsible decisionmaking concerning U.S. immigration. Whether environmental criteria are appropriate grounds for revising immigration policy encompasses questions that are within the grasp of social and environmental research.

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INTRODUCTION

Each of the most recent major amendments to the Immigration and Nationality Act includes a requirement for the federal government to assess the environmental impact of alien immigration on the United States. Specifically, the Immigration Reform and Control Act of 1986 [IRCA] specifies that the Triennial Report to Congress shall provide a

". . . description of the impact of immigration on environmental quality and resources . . ." (Sec.401(b)(3)). The Immigration Act of 1990, which focused on legal immigration, gives the Commission on Legal Immigration Reform the mandate to consider the ". . . social, demographic and natural resources impact of immigration . . ." (Sec.141(c)(1)(C)), and also requires the government to provide statistical information that is ". . . useful in evaluating the social, economic, environmental, and demographic impact of immigration laws . . ." (Sec.142(c)(1)).

These statutory mandates to consider the relationship between U.S. immigration and environmental processes and issues provide an opportunity for social and environmental scientists to expand theoretical and empirical knowledge concerning population-environment dynamics by

giving specific attention to processes of international migration, mobility, and circulation. The goal of this report is to contribute to this area of policy analysis by reviewing existing scientific literature concerning immigration and environment, to identify research issues emerging from extant scholarship, and to

develop recommendations for areas of needed research that will benefit the immigration policy process. It is important to note at the outset that remarkably little hard evidence exists about the environmental effects of alien migration to the United States. A great deal of speculation exists about the nature of the relationship and there is increasing popular commentary about the degree to which immigration is associated with environmental problems in local areas as well as the nation as a whole. The direct or causal effects of U.S. immigration on the environment have not been established, however, through scientific study. Moreover, there are significant limitations in U.S. statistics on immigration and population for the study of environmental impacts.

The report serves as an initial review of four salient dimensions of a policy relevant research agenda concerning the relationship between U.S. immigration and environmental issues. First, we con

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sider the relevance of contemporary theoretical perspectives on the relationships among population change, migration, and environmental processes and problems. Second, we review the extant

scientific literature concerning these relationships. While primary attention is directed to studies pertaining to the United States, the review seeks to be comprehensive by considering relevant research concerning migration and the environment in other countries and regions; particular attention is given to research concerning immigration and the environment in Australia. Third, we consider the relevance of existing methodological approaches to studying environmental change for the analysis of the environmental consequences of alien immigration and international population movements to and from the United States. Environmental impact assessment and population-environment monitoring systems are considered specifically. Fourth, given existing theory and methods, we reflect on the information requirements for analysis of immigration-environmental relationships at various geographic scales in the United States. The degree to which federal statistics can support analyses of the role of immigration in national, regional, and local population dynamics is considered a critical issue for policy research concerning immigration and the U.S. environment.

Throughout the review, we draw on scientific literature specific to the United States as well as studies and perspectives on human environmental impact specific to other countries and regions, including areas within the developing world. We thus attempt to glean from this array of scholarship insights about theory, methods, and empirical research that are relevant for developing a research agenda for the U.S. context. The paper concludes with an outline of research priorities concerning the consequences of immigration for environmental processes and trends in the United States.

A Further Rationale

As implied above, the legislative mandate for information on the environmental consequences of U.S. immigration provides an important opportunity for policy relevant research and also for the expansion of scientific literature concerning population-environmental dynamics. In short, there is an opportunity for both basic and applied research concerning human-environmental interactions. There is also a need for such research because conclusions or inferences about the environmental consequences of immigration may be preceding systematic study of the issues (for example, Mann

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1990; Population-Environment Balance, Inc. 1992; Simcox 1992; Federation for American Immigration Reform 1991). It is relevant to note that the premature use of environmental arguments in debates over immigration was anticipated in Canada a few years ago. The Canada Employment and Immigration Advisory Council observed that given evidence about the positive economic impacts of immigration, the Canadian public might be expected to shift its attention to another rationale to restrict immigration, and that argument could likely settle on environmental issues (see Canada Employment and Immigration Advisory Council 1991:30-31).

It is also interesting to note that the discussions about environmental effects are somewhat reminiscent of the tone of statements made in the early decades of this century concerning the social and cultural effects of immigration, e.g, in such statements as the one below made in 1926 by George Cutten, President of Colgate University concerning the effects of immigration for the quality of the U.S. population and society. [Currently on display in the exhibit on immigration restrictionism at the Ellis Island Museum, perhaps it is not the most appropriate illustration, but it holds intrinsic interest for this writer.]

The melting pot is destructive to our race. . . . We must either build up from own resources and conserve our race power, or else we must admit only such immigrants as shall strengthen and not weaken our race, or both. The danger the `melting pot' brings to the nation is the breeding out of the higher divisions of the white race and the breeding in of the lower divisions. (Wood 1923)

A recent statement by the Federation for American Immigration Reform concerning the environmental effects of current alien immigration to the United States directs attention to the relationships among immigrant fertility and population growth within the context of declining environmental quality and resources:

WHY A LIMIT?

Our Natural Environment

Says There Must Be Limits

on Increasing Numbers

of Immigrants

We are plagued by water shortages, overflowing landfills, crowded transportation systems, deteriorating wilderness and recreation areas and toxic pollution,

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ailments that point very clearly to the fact that the U.S. is overpopulated. . . .

Some experts point to the increasing number of immigrants and refugees admitted to this country during the last ten years as one reason for the rising fertility rate. Most of the recent entrants to the U.S. have come from countries with high fertility rates, and many who come are in their childbearing years. . . . (Federation for American Immigration Reform 1991:41-42)

Even somewhat more scientific accounts of U.S. immigration draw illusions to ecological concepts. Note, for example, the reference to limits on the absorptive capacity in a recent publication of RAND-Ford Foundation Program for Research on Immigration Policy:

Policy Questions Regarding the Flow of Immigrants

Policies of the last decade leave three central issues regarding new immigration unresolved.

Aggregate Total Numbers. Each of the three significant immigra

tion measures passed by Congress during the 1980s has been considered independently, and each has had an expansionary and compounding effect on the size of legal immigration. For the most part, each has been considered without a unifying debate on the overarching

question of how much total immigration . . . the nation can productively absorb. Of particular note, policy makers have not examined the absorptive capacity of the major metropolitan receiving centers.

. . . The policy question will be how to respond to the growing pressures [for immigration to the United States]: Is there a limit to the nation's absorptive capacity , and , if so, what is the limit? [emphasis added] (Rolph 1992:50-51)

These are appropriate questions reflecting ecological perspectives concerning the human environment. While Rolph does not define explicitly absorptive capacity, we can infer the concept to refer to the capacity of societal institutions to receive and integrate alien migrants (as opposed to the addition of native births)

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into local communities, regions, labor markets, and, ultimately, national society. Absorptive capacity is thus related to an area's carrying capacity [see pages 24-25 below] but encompassing the availability of social, economic, and political resources effectively to accommodate newcomers.

Increasingly, however, there are popular interpretations of the effect of immigration on both the social and physical environment. While questions concerning absorptive capacity are similar to the above statements, definitive answers are being forwarded identifying immigration as the cause of a range of social and environmental problems. Excerpts from the San Francisco Examiner-Chronicle are illustrative:

Bursting at the Seams

. . . It is time to consider a moratorium on immigration until we have provided a lamentably lacking element in our governance system—a population policy. We need to determine the carrying capacity of the state.

Fiscal problems aside, how many people can our dwindling natural resources support at a reasonable standard of living?

Consider water, for example. As we have learned recently, the filling of the reservoirs by this year's rains will not solve the long-term water shortage.

Even with reservoirs at capacity there is not enough water to satisfy present demands, much less an unending demand for more. The population grows; the water supply does not. . . .

Water conservation can extend existing supplies, but you can only tighten the belt up to a point. A continually growing population will overtake all efforts at conservation.

Another declining resources is topsoil. . . .

. . . Where once there were miles of orange groves beneath snowy mountains, there are now miles of besmogged suburbs, and

the mountains are seldom

visible. . . .

Half of the state's popula-

tion increase comes from net

births . . . [net increase]. But most of the births that increase

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the population are attributable to immigration. (Gilliam 1993:7,12)

The point is that statements currently are being presented about the relationships among population, immigration, and the environment in the United States. It is critical that scientific evidence concerning these relationships enter into the policy arena both to inform the immigration policy process and to clarify the multiple causes and correlates of environmental issues. As Preston (1993:601) observes, "[d]iscussions of appropriate levels of immigration inevitably will become heated, and it is important to begin now to establish a sound basis for any revisions."

PERSPECTIVES ON THE ROLE OF MIGRATION IN POPULATION-ENVIRONMENT DYNAMICS

Introduction

Theoretical perspectives on the relationship between population and the environment generally fall into three broad camps, each with different implications for policies concerning population regul

ation and migration. These perspectives have been critically presented by Hogan (1992), Lowe and Bowlby (1992), Fincher (1991:9-16), and Lowenthal (1992, 1990) among others, and will be described only briefly here. Neo-Malthusian perspectives conceptualize a negative relationship between population growth and the availability, and, increasingly, the quality of environmental resources (see, for example, Ehrlich & Ehrlich 1992; Grant 1992). More optimistic perspectives emphasize the enhanced potential inherent in positive population growth for social, economic, and technological progress and, hence, the means to solve environmental problems (see for example, Simon 1990, 1992; Repetto 1987);

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Boserup conceptualizes population pressure as a stimulus to technological innovation and more effective use of resources (Boserup 1981). A third perspective, less associated with proscriptions concerning population control policies, identifies population growth as a factor that retards efforts at social and economic development and exacerbates social inequality within poor societies (see Mink 1992; Caldwell 1985; cf. National Research Council 1986; United Nations Secretariat 1991).

The general model of environmental impact has been presented and applied by Ehrlich & Ehrlich (1990) among others (see Marden & Hodgsen 1975). Environmental impact [I] is conceptualized as a function of population characteristics [P], patterns of consumption [A, for affluence] and technology [T], the use and manipulation of energy and other natural resources. This model has provided an organizing framework for much of the debate concerning population and the environment. Neo-Malthusians emphasize the significant influence of population growth for environmental impact, while "optimistic" perspectives give primary importance to changes in technology and social and economic organization in mitigating the effects of the other two factors.

The model has been criticized for the incomplete conceptualization of the causal components and the lack of grounding in social scientific theory. Meyer and Turner (1992:52) note that the model ". . . suffers from the handicap of a mismatch between its categories of driving forces (apart from population) and the categories customarily used in the social sciences. Neither "affluence" nor "technology" as defined is associated with a substantial body of social science theory; any bridges between the IPAT and other approaches would have to be built between these categories and those better-conceptualized aspects of behavior and social structure that may drive

and limit changes in production and

consumption." Demeny (1991:410-12) comments on the implication of independence among the three components of environmental impact and hence the lack of conceptual attention to the ways in which changes in population, consumption and technology are interrelated.

The degree to which the population concept is well specified or connected to social theory can also be contested: uses of the model focus primarily on the increase in population size without conceptualization of the different sources of population growth, for example, natural increase relative to net migration. For

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example, critical attention to the interrelationships among migration, patterns of consumption, and shifts in technology is not accommodated in the model; in general, testable hypotheses about the effect of population movements on social and technological change are not derived from the model. Relatedly, the model frustrates a dynamic perspective concerning the consequences of changes in the factors over time. Pragmatic considerations of short-term versus long-term relationships are not prominent in the theoretical discussions.

In spite of these conceptual deficiencies, however, the IPAT model has become an important conceptual construct influencing general thinking about population-environment relations. Keyfitz (1993:547) clarifies the strengths and weaknesses of the general model and states the hypothesis clearly:

If all else is equal, action damaging the environment is directly proportional to the number

of people. That at least seems the most appropriate initial

hypothesis.

Keyfitz provides examples of circumstances in which population has a more than proportional effect on environmen

tal change, that is, a 1 percent increase in population results in more than 1 percent change in some environmental characteristic, for example, the stock of some natural resource; similarly, one can illustrate circumstances in which population growth is associated with a less than proportional environmental impact. According to Keyfitz, however, "(t)he burden of proof is one anyone who argues against the proportionality hypothesis in either way" (1993: 547).

Population-Environment Models and Migration

This discussion of general perspectives on population and environment suggest that an appropriate modification of theory is the improvement of the ways in which population processes and concepts are specified. For example, the effect of in-migration on environmental change is likely to be different from the effect of above replacement fertility or of mortality decline, thus, using the vocabulary of Keyfitz, immigration may have a different level of proportionality than other demographic processes. Hence, results specific to demographic behaviors (mortality, fertility, and geographic mo

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bility and migration) will be relevant to different policy responses.

Theoretical discussions of population-environment relationships vary in

the degree to which migration is

critically considered. For example,

neo-Malthusian perspectives give greater conceptual prominence to the negative effects of aggregate (positive) population growth and hypothesize that any source of growth, such as positive net migration, has negative consequences for the environment. The application of these perspectives to the United States, for example, leads to conclusions about the negative effects of alien immigration for preservation of resources and environmental quality. Not surprisingly, more optimistic conceptualizations draw the converse hypothesis about the role of migration on technological and environmental change (see Simon 1990). Fundamentally, however, the role of migration in environmental change derives directly from the underlying conceptual model of population-environmental dynamics: the effect of migration is specified on the basis of its (positive) contribution to population growth.

Among the recommendations of the National Research Council Committee on the Human Dimensions of Global Change

was the need to ". . . 'unpack' broad concepts, such as technological change, economic growth, and population growth, that are frequently offered as explanations of how human activities cause

global change" (Stern, Young & Druckman 1992:97; see also Ness, Drake & Brechin 1993b:377-406). Such recommendations hold particular relevance for specifying the role of migration in environmental process and change. For example, in a critique of perspectives on population and the environment, Hogan (1992:113-14) identifies, first, the theoretical disadvantages of the concept of aggregate population growth and, second, the advantages of considering more meaningful demographic processes:

But in all of these cases [theoretical perspectives], with a pure or moderated or even inverted Mathusianism, what we see is an emphasis on the volume or growth rate of population. The refrain is always the race

between population and

resources. The question of

the population/resource or population/environment relation is reduced to a unidimensional relation. the ways in which patterns of fertility, morbidity, mortality, migration, nuptiality, and

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age structure relate to environ-mental change, have received little attention. What seems to have occurred, on the one hand, is that for the Neo-Malthusians, there is not reason to go beyond this point; the relation is clear, and the solution obvious. On the other hand, the critics look for the causes of environmental problems in other processes. It is as though population growth causes everything or population is unimportant.

What is needed is an analysis

of the relationships of demographic dynamics, in all their complexity, with environmental change. . . .

An important starting point in efforts to go beyond such generalizations is to decompose what we mean by "population pressure" which has been nearly universally understood to mean excess numbers with clear conclusions about policies to reduce fertility rates.

Hogan's observation about the derivation of fertility policy proposals is increasingly applicable to policy recommendations to

restrict or to promote immigration. Such proposals similarly derive from inherent conceptualizations of the environmental effects of aggregate population growth.

The theoretical necessity to disaggregate the components of population growth in order to specify the role of migration (or any demographic behavior) in environmental processes is reinforced by Mink (1992) in his discussion of the interrelationships among population, development, and the environment. In reference to developing countries, Mink identifies the range of effects of migration on environment processes that are conditioned by social and economic factors in both places of origin and destination:

Migration often represents a response to imbalances between population levels and the capacity of local environmental resources to support them. There are also potent environmental impacts in areas receiving the migration, which will differ

according to the form the migration takes—whether of individuals or households, seasonal or permanent, to frontiers or established communities—and which can either mitigate or exacerbate the environmental impact of

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population growth. Some forms of episodic migration, such as flight from political strife, can expose environmental fragile areas to massive population increases . . . (Mink 1992:26-27).

Implicit in Mink's discussion is both an emphasis on the importance of shorter-term effects of migration on developing areas, particularly refugee migration, as well as the importance of incorporating causes and characteristics of migration processes in studies of environmental change. Finally in their critical analysis of population-environment perspectives, Arizpe, Stone, and Major (1994:340) state:

Population must not be reified as if the simple numbers of human bodies were all that mattered. From the standpoint of population/environment analysis, people are significant in terms of what these humans do in a matrix of social and environmental interactions. This means that population must be understood as a process of biological and social reproduction whose components are principally interactions. Research must focus on these interactions as the relate to the three determinants

of population—fertility, mortality and migration.

They emphasize the relevance of study on the relationship between migration and environmental change and the role of gender and income inequality in migration processes and changing environmental processes, such as patterns of consumption, resource extraction, and waste production (Arizpe, Stone & Major 1994: 339-40).

Perspectives on the relationship between global dimensions of urbanization do focus on the significance of migration as a component of regional population growth and redistribution (see Keyfitz 1991; Berry 1990; Detwyler 1971 ) but generally in the form of regional rural-urban movements and labor circulation. Perspectives on optimum city size, in contrast, grapple with the effect of the aggregate concept, urban population growth, on urban efficiencies in accessibility of services and resources, and urban environmental characteristics, such as residential and industrial density, air and water quality, pollution, waste disposal, and sewage processing. Less attention is given to the nature of the relationships between specific sources of urban growth, for example, alien immigration versus internal migration, and

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social and environmental outcomes in urban areas and metropolitan regions, although issues of population homogeneity and urban problems have been raised (see for example, Speare & White 1990, 1992; Fincher 1991; Murphy, et al. 1990; cf. Muller 1993:211-13).

Migration and Global Environmental Change

The degree to which migration processes are considered in conceptualizations of population-environmental linkages is a function of both theoretical perspective and geographic scale of analysis. Perspectives on global environmental change generally focus on overall population growth without significant or specific attention to component processes underlying patterns and trends in geographic distribution (see, for example, National Academy of Sciences 1991; Ehrlich & Ehrlich 1990; Stern, Young & Druckman 1992; Barry, Mather & Sdasyuk 1991; Mathews 1991a; also Royal Society of London and National Academy of Sciences 1992). Moreover, models of global population change emphasize the implications of regional variations in population growth but tend to obscure the role

of international or interregional migration in the global outlook and regional trends (see Keyfitz 1991; Demeny 1990; Goudie 1990; Smil 1990, 1991; Bongaarts 1992; also Coale 1975). In this sense, some contemporary perspectives are reminiscent of earlier considerations of population growth for the environment (see, for example, Turk, Turk & Wittes 1972; Waldron & Ricklefs 1973; Detwyler 1971a; cf. Dubos 1971; see also Goudie 1990).

Perspectives on U.S. Immigration and the Environment

Perspectives on the national and regional environmental impacts of U.S. immigration similarly reflect underlying theoretical frameworks. Simon (1990) has

emphasized the potential contributions to human capital and the potential for technological innovation deriving from positive population growth in the United States and alien immigration. Short-run costs of immigration are distinguished from long-term benefits; age composition of immigrants, rather than such characteristics as national origin or education, is considered the important policy issue relevant for questions of immigration im

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pacts. Ehrlich and Ehrlich (1992), in contrast, have used the IPAT model to illustrate the degree to which the United States is over populated and the need to constrain population growth. These authors recognize both the long-term benefit of reducing levels of fertility as well as the political and sociological difficulties in recommending the cessation of immigration as a route to stationary (zero) population growth (Ehrlich & Ehrlich 1992:130-31).

Most neo-Malthusian perspectives on the environment, however, generally highlight the role of alien immigration in U.S. population growth and often focus on the contribution to future growth resulting from the descendants of current immigrant streams (see for example, Bouvier 1991, 1992). The results from these studies, often population projections, present images of unending population growth deriving from the rising demand for immigration within developing countries and positive annual levels of permanent immigrant additions. Inherent in these perspectives are critical conceptual and analytic issues concerning immigration and population growth. For example, there is contention over appropriate approaches to conceptualizing the source of population growth resulting from international migration in annual measures

of population growth as well as in population projections. Interpretations of population projections must also be

resolved with results of formal demographic studies of the relationship between annual immigration and the achievement of a national stationary population.

Conceptual Issues Emerging from Models of Population-Environmental Change

Several analytic issues emerge from this review of the conceptualization of migration in population-environment models. Very fundamentally, the conceptu-alization of immigration as a component of population growth must be revisited. Second, both geographic level of analysis or geographic scale and temporal reference, for example, short-term or long-term, must be specified in theoretical models and, ultimately, in empirical research. The effects of immigration on environmental processes may be expected to be significantly different for metropolitan areas, rural communities, and states. Similarly, the setting of policy goals regarding immigration and the

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environment and the process of policy evaluation require explicit time frames for analysis and assessment. A third analytic issue is the importance of understanding linkages or connections among geographic areas, economic sectors, and through time. For example, the concentration of immigration in certain metropolitan areas in the United States may have environmental consequences for areas and natural resources geographically removed from the cities.

Immigration as a Component of

Population Growth

There is not consensus among demographers concerning the most appropriate approach to conceptualizing, and hence measuring, the proportion of population growth due to migration or the role of immigration in future population growth. For example, partitioning annual population growth among demographic components to yield the proportions (in

percents) of growth due to immigration ignores the overall level of population growth and also assumes all sources of population change are measurable (see pages 57-59 below). Warren (1994b) suggests the comparison of annual immigration to total additions to the population, that is, immigrants and births is a more

appropriate approach to thinking about immigration's contribution to population growth (see also Keely 1974). Weeks (1992 ) advocates the migration ratio: net migration as a proportion of natural increase, (births minus deaths) for areas. Simon (1990) argues for the use of the ratio between either the flow of immigration (immigration admissions or arrivals) or the stock of immigrants (such as the foreign-born population) to the residential population in a given year as a gauge of immigration of both demographic and social impact.

Similarly, there are differing approaches to conceptualizing the impact of immigration on future population growth in both the short and long-run. Population projections simulate future patterns of population growth by making assumptions about changes in behavioral

patterns of demographic processes (mortality, fertility, and migration), by age and sex, and often by other social demographic characteristics such as race and rural or urban residence. The effect of the demographic components of growth on future population size and structure (age and sex composition) is shown by comparing the results of different projection series in which different assumption are modelled. For example, the U.S. Census Bureau conducts population pro

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jections assuming the continuation of current levels of net immigration (see page 59 below) and projections assuming zero net immigration.

Problems in interpreting the results of population projections concerning the contribution of immigration population growth have been discussed by demographers (see, for example, Edmonston & Passel 1992; Keely & Kraly 1978; Kraly 1981). A fundamental issue concerns the choice of reference data for measuring the demographic impact of immigration: nearly 100 percent of U.S. population growth since 1790 has resulted from immigration and the descendants of

immigrants. There are empirical difficulties in developing assumptions about fertility among first and subsequent generations of immigrants. Further, emigration is often not modelled as an age

specific propensity, but is subsumed with a concept of net immigration. Given the wide use made of population projections in discussions of U.S. immigration policy issues, it is critical that conceptual issues in both approaches to modelling and in the interpretations of results be clearly set out.

Similarly the results of formal demographic analysis of immigration and population growth should be incorpo

rated into models of population and environment. As mentioned above, there is a solid body of demographic theory that has revealed the relationship between positive immigration and the achievement of population stabilization at zero annual growth, that is, a stationary population (Keyfitz 1971; Coale 1972; Pollard 1973; Espenshade, Bouvier & Arthur 1982; Mitra 1983; Espenshade 1986; Feichtinger & Steinman 1992). A stationary population is consistent with annual immigration given fertility at replacement or below replacement levels. The ultimate size of the population is a function of the level of fertility and mortality, annual levels of immigration, and the age composition of immigrants. These results suggests the importance of better understanding demographic characteristics of immigrants, specifically fertility and age characteristics, in order to interpret more effectively results of models of immigration, population growth.

Geographic Scale and Temporal

Specification

Geographic scale is a critical conceptual and analytic dimension of contemporary perspectives on population and environment. The importance of considering the role of demographic processes in envi-

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ronmental change on regional and local scales of analysis is increasingly emphasized in literature on the relationship between economic development and the environment in less developed countries (see, for example, Arizpe, Stone, and Major 1994; Mink 1992; Ogata 1989:48; United Nations Secretariat 1991; Glaser 1980; Milliman 1992; Huguet 1992). Mink (1992:13), for example, calls for both spatial and temporal specification:

The impact of population intervenes along three main dimensions: its scale in relation to the resource base, its rate of growth, and its redistribution across resources through migration. Population's impact on the environment is critical in some countries or regions within countries, but is less important in others. Moreover, the three dimensions will not be equally important for the environment in different places and points in time. Thus, assessments of population's impact on the environment, and the appropriateness of addressing such impact through direct population interventions, need

to take local circumstances into account.

In reflecting on the study of environmental processes among island ecosystems, Glaser (1980:9) offers a very clear statement on the "limitations of global synthesis" in the study of population and the environment:

The population/resource/environment situation differs from country to country and varies even from area to area within most countries, in particular the larger ones. The problems of assessing population/resource ratios, and of defining measures for their beneficial adjustment, must be tackled on a disaggregated and areal basis. In fact, there seems to be a need for almost every country to develop a population/resources environment model for its particular national situation for its major geographic subdivisions.

Bilsborrow (1992) argues for local and regional studies as opposed to cross-country analysis on the basis of principles of research design and the analytic goal to move beyond descriptive studies of covariation to conclusions concerning causal processes:

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While cross-country-level data have the appeal of generaliza-bility, there are important reasons for focusing research efforts at the individual country level. One is the much greater possibility of controlling for other factors that influence demographic and environmental change, such as national resource endowment, climate and topography; soil quality; transportation linkages to markets and cities and availability of off-farm employment; access to family planning, health and education facilities; . . . and national and local government policies relating directly to the environment, such as restrictions against tree cutting, cost of logging concessions, and protection of parks and nature reserves. All of these factors, and undoubtedly others, may influence demographic processes, agricultural and land use change, and environmental degradation in rural areas.

A second reason for preferring within-country studies is that aggregate country-level data cannot relate well (differences in) natural resources trends to

(differences in) demographic variables. If it were true that countries with faster rates of population growth appeared to be experiencing faster rates of forest loss, this would not necessarily mean that the two are

related, particularly from the production or supply side, as per the focus in this paper. One would need to see if those areas within the country experiencing forest loss are also the areas experiencing population growth (in-migration). This can only

be addressed at the country level . . . (Bilsborrow 1992:144-45)

Critical perspectives on the concept of carrying capacity further underscore the need to relate population and environmental processes on local and regional scales defined most appropriately by ecological analysis (see Bayliss-Smith 1980; Glaser 1980; Brookfield 1980; McCall 1985; Talbot 1986; Santos 1990:39-40,75-76; see also McConnell 1991). Carrying capacity is the size of population that can be supported by the resources of an ecological system. In human population, the concept must be understood to be dynamic, that is, open to change through technological and social factors. Hogan argues for the value of the con-

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cept of carrying capacity in order to relate demographic processes, resources, environmental trends, technological change, and patterns of production and consumption within specific regions:

The value of the concept of carrying capacity is that it should direct our attention to specific ecosystems, exploited with spe-

cific technologies, to produce a specific standard of living. Here one may meaningfully relate population pressure to environmental degradation. (Hogan 1992:116)

Because carrying capacity is altered by technological and institutional change, the conceptual framework requires the specification of the temporal context for analysis. Hence, the short-term outcomes of migration for environmental change may be conceptualized quite differently for places and regions in comparisons to models with longer-term time horizons in which feedback between migration and social and technological change may be envisioned (cf. Simon 1990:188-92). A useful discussion of issues in the interpretation of the concept of carrying capacity is provided by Cater and Goodall (1992:312-13) who consider carrying capacity within specific destinations for

tourists in Australia (see also Bayliss-Smith 1980; Huguet 1992:388). Because of the relatively short-term

impact of increasingly large numbers of certain types of international migrants—tourists, business persons, students—in selected places in the United States, it may also be useful to explore the use of the concept of carrying capacity in relationship to the demographic notion of "person-years" of impact (K. Woodrow 199 ).

Meyer and Turner summarize these issues of scale concerning perspectives on population and the environment and also with relevance to conceptual models and research design: "Comparative assessments assume that if population is a key driver of environmental change, then the pressures of population (e.g. density) should closely match the magnitude of various kinds of environmental change across regions and locales" (Meyer & Turner 1992:53).

Spatial, Sectoral, and Temporal

Linkages

Finally, there is emerging emphasis on the significance of linkages across geographic scale and among regions that holds theoretical potential for informing

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conceptual models of the relationships between migration and environmental processes. The published results of interdisciplinary symposium, The Earth As Transformed by Human Action (see Turner, et al. 1990) address conceptual issues concerning interregional and intersectoral linkages by disentangling, both conceptually and empirically, the temporal and spatial patterns of the effects of human society on global and regional environmental processes at different scales. In this regard, Merchant (1990) provides critical insight to the characteristics

and limitations of models of society-

environment interactions. Again, however, the role of interregional and international population movement in processes of transformation in selected

regions is not highlighted either in theory or application (see, for example, Ezcurra 1990).

Emphasis on linkages among regions and across geographic scales is often matched with attention to the dynamic dimensions of societal and environmental processes. For example, the University of Michigan Population-Environment Dynamics Pro-ject (Ness, Drake & Brechin 1993b) has emphasized the need for interdisciplinary study of human-environmental interaction and for theoretical refinement of general models of environmental impact

(cf. Ehrlich & Ehrlich 1990). Transitional analysis, that is, interaction among processes of change, is underscored (cf. Lutz 1994:63; United Nations Secretariat 1991:58). Drake (1993) identifies several areas of global transition which characterize population-environmental dynamics including the demographic transition, epidemiological transition, and the urbanization transition. While trends in international labor and refugee movements are noticeably absent from this conceptualization, the framework is conducive to similar consideration of the prominence of international population movements in regional and global dynamics. The importance of determining the degree of synchrony in rate of change in transitions is particularly salient for the analysis of the role of international migration in social and environmental change in the United States (Drake 1993:334-48).

It is interesting to note that studies that place theoretical emphasis on the linkages between developed and developing countries and increasing internatio