Global Footprint Mapping & Micro-Simulation: A Tool for Risk Management

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Lezlie MORINIÌöRE1, Richard TAYLOR, Ph.D.2 and Mohamed HAMZA, Ph.D.2

There is little concrete evidence to justify predictions of ‘environmentally-induced migration’. More perplexingly, empirical evidence has not yet justified ‘environmentally-induced migration’ over the past 200 years. Global data do exist, however, that enable a more systematic assessment of both the geo-temporal distribution of such migrants and the sets of drivers that trigger and describe observed trends. Such a database, entitled the “Global Footprint” is part of a broader initiative by Stockholm Environment Institute (SEI), entitled Transformations in Risk, that will also use historical transects, pathway analysis and case studies to explore tipping points in humanitarian crises.

The Global Footprint will compile the best-available evidence through space (gridded, national or regional) and time (longitudinal, up to hundreds of years). All available global datasets will be tapped to explore triggers of human mobility and the footprint of these population movements.åÊ The Global Footprint will help visualize environmentally-induced migration and it will subsequently guide a GIS-based micro-simulation exercise that systematically explores the weight of various drivers acting on independent agents within dynamic contexts of policy, perception and capacity. The Global Footprint will reveal important patterns that can be used to identify potential migration ‘hotspots’ thereby facilitating risk management.Image of a foot made up of different ecosystems.


Individuals have sought refuge from extreme events since the dawn of time. There is no set definition or characterization of what constitutes an individual seeking refuge from environmental or climatic extremes such as land degradation, drought, desertification, sea level rise, or other natural hazard events.åÊ Professional literature refers to these migrants as “climate refugees” [1, 2] or “environmental refugees” [3-13]. The first author to use the term ‘environmental refugee’ was the International Institute for Environment and Development [14]: “Third World environmental refugees are increasingly fleeing worn out lands for industrialized countries of the North”.åÊ One year later, after the heavily quoted paper by UNEP’s El Hinnawi [15], it became a household term.åÊ According to the United Nations ConventionåÊ [16] relating to the Status of Refugees, however, a refugee is “any person who, owing to a well founded fear of being persecuted for reasons of race, religion, nationality, membership of a particular social group or political opinion‰Û_”. The new terms remain controversial and the United Nations does not formally recognize these migrants or keep a central tally of their numbers. Lack of formal recognition results in the systematic neglect of displaced, highly vulnerable populations across the globe.

Saunders explored the origins of the construct of ‘environmental refugees’ from a political ecology perspective and, tracing it back to neo-Malthusian literature, she warns against institutional pressure to use the term for ulterior motives [17]. Kibreab attributes the origin of the term to a clear desire by nation states to depoliticize displacement and thus remove it from their lists of responsibilities [18].åÊ Dissecting United Nations discursive politics, McNamara provides two reasons for the U.N. unwillingness or refusal to govern climate migrants: changing attitudes towards multilateralism creating a “heightened need to protect state borders” and the move away from state responsibility for degraded environments, thus “relinquishing themselves of their environmentally irresponsible actions” with global repercussions [19]. Rather than participate in a discourse of denial, a commission of U.S. retired admirals uses the growing body of expert literature to crucify ‘climate migrants’ as the next ‘public enemy’. In a short release entitled “National Security and the Threat of Climate Change”, migration is mentioned 44 times [20].åÊ It is clear that, despite vivid proof of a very real and growing phenomenon, numerous discourses have been constructed to sometimes amplify the threat from, and at other times deny, the existence of ‘environmental refugees’.åÊ Bach pleads for an aggressive international leadership to rethink migration policy in general, using a less traditional notion of security: helping make homelands more secure thereby giving inhabitants the choice to stay there [21].

Table 1
Table 1 showing years and respective number of documents.

A Rapidly Growing Body of Literature

Over the past 50 years, at least 500 authors (academics and practitioners combined) have written more than 300 documents to offer specific causes and consequences and to take positions that explain the diverse links between migration and the environment.åÊ The interest in environmentally-induced migration has grown exponentially at least since Petersen proposed, in 1958, a typology of migration featuring what he called ‘primitive migration’ –one “resulting from an ecological push: a movement related to man’s inability to cope with natural forces”[22]. The most prolific contributor of texts on this topic, Norman Myers, is an ecologist. Myers actively promotes the concept as a very real phenomenon, driven at least partially by poor policy and marginalization, and triggered by environmental crisis [3, 4, 23-30]. Other publications are spawned from the fields of migration, geography and climate change.

Up to and including 1970, only 15 documents had been published and by the 1980s, 24 more.åÊ The 1990s saw 104 documents and the 2000s (to date) already 179 publications. See Table 1.åÊ The events and/or workshops that may have spawned or influenced these publications are detailed in Annex 1.åÊ Eighty seven (87) different professional peer-reviewed journals published 153 academic articles that were included in the database.åÊ Four journals published at least five of these articles and 21 journals published at least two of them.åÊ Ominously, Disasters published 23 articles, Population and Environment, 9 articles, International Migration Review (IMR), 6 articles, and Ecological Economics, 5 articles. See Table 2.

Table 2
Table 2 showing number of articles and name of journals in which they appeared

At least 32% (n=103 of the 321 publications) were themselves ‰ÛÒor featured‰ÛÒ in-depth case studies of a particular region (usually tied to a common event or process) or country. The largest subset of these featured Africa (n-47), while other significant clusters included Asia (n=23) and the Americas (n=22). See Table 3. The most commonly targeted countries were Bangladesh (n=23) and Ethiopia (n=9).

Most researchers agree that it is impossible if not disingenuous to isolate drivers of migration, as there are always multiple sets of triggers. Few theories have been grounded to explain the singular contribution of the environment among many push factors. To each discipline, his own focus: just as economists have tended to emphasize purely monetary influences on migration, psychologists have been concerned with rationality, human geographers with space (distance, gravity) and most recently physical scientists (climatologists, ecologists, etc.), with the environmentåÊ –all as major determinants of human migration.åÊ To date, as the greatest push has been to project the future rather than to explain the past, and theories are hard pressed to reflect current and changing realities. Empirical evidence begs assembling in part to update the theoretical foundation.

Table 3
Table 3 showing location of case studies


Current estimates of environmentally-driven migration abound, based largely on back of the envelope calculations and in-depth case studies in isolated areas across the globe. The International Federation of the Red Cross estimate 25 million “climate migrants” [31]. While skeptics claim that there are no “climate migrants”[32], leading author Myers proposes a “conservative” estimate of 150-200 million over the next fifty years, due primarily to global change [4]. The Stern Review [33] and Friends of the Earth [2] also estimate, independently, 100 million by 2050.åÊ Christian Aid has recently reported one billion environmentally-driven migrants by 2050 [34]. Most researchers concede that whatever its current number due partly to climate change, the phenomenon is likely to accelerate. To date, however, no data source is recognized to defend the magnitude of this phenomenon.

There is little concrete evidence to justify these predictions of ‘environmentally-induced migration’. More perplexingly, however, is that there is no empirical evidence that has justified migration over the past 200 years as ‘environmentally-induced.’åÊ What can empirical evidence on a global scale offer to detect the footprint of migrants with origins in the 1846 Irish Potato Famine, the 1930s Dust Bowl, escalating resource scarcity in Darfur and Mexico or Hurricanes Mitch and Katrina?åÊ Global data exist to enable a more systematic assessment of both the geo-temporal distribution of such migrants and the sets of drivers that may describe or explain observed trends. Such a database, entitled the “Global Footprint”, is currently being compiled by Stockholm Environment Institute (SEI) in collaboration with the University of Arizona (Office of Arid Lands Studies), as part of a SIDA-funded strategic initiative investigating transformations in risk patterns and tipping points into humanitarian crises.


Set, Subset (Candidate Dataset)

  • Set A: Environmental Drivers
  • ‰Û¢ Natural Hazards (CRED‘s EMDAT)

    ‰Û¢ Climate Extremes (CRU/CEI)

    ‰Û¢ Slow Onset Processes

    ‰Û¢ Resource Scarcity

  • Set B: Non-Environmental Drivers
  • ‰Û¢ Economics (UNDP’s HDI)

    ‰Û¢ Conflict and persecution (PRIO)

    ‰Û¢ Population Growth (UN Pop Div)

  • Set C: Human Displacement
  • ‰Û¢ Urbanization (UN Pop Div)

    ‰Û¢ Remittances (WB)

    ‰Û¢ IDPs/Refugees (UN)

    ‰Û¢ Residual Migration (HYDE)

    Methodology and Preliminary Application

    To fill this gap, the Global Footprint aims to compile the best-available evidence through space (multiple scales:åÊ gridded, national and regional) and time (up to hundreds of years, longitudinal) to explore patterns of migration of the recent and less recent past. All available global datasets will be tapped to explore triggers of human movement (push factors only) and the footprint of that movement.åÊ Triggers Set A, will include environmental events or processes such as land degradation, deforestation, natural hazards (drought, storms and flooding, tsunami), climate extremes and sea level rise.åÊ Set B, Non-environmental drivers, will include the less debated drivers of population growth and economics.åÊ Proxies for displacement will form Set C; it will draw on datasets that capture snapshots of human displacement such as urbanization, remittances, migration stocks, residual migration and refugee flows. Potential data sources and variables for each of these are being explored and assembled as the first part of research, see text box, side, for major candidate datasets.

    As a preliminary venture into existing global data, nine (9) national-level variables were compiled to represent each of the datasets.åÊ For Set A, Environmental Drivers, a drought index was created reflecting frequency, intensity and magnitude of events. For Set B, Non-Environmental Drivers, Gross National Product per capita, Annual Population Growth Rate, Human Development Index and a Conflict Index were assembled. To reflect the human footprint, Set C, Remittances, Internally Displaced Population (IDP) Stocks, Refugee Stocks and Urbanization were compiled.åÊ Each of these sets was aligned through space and time (same year, and at one, two and three-year time lags) and their relationships analyzed.

    Given the resolution of these preliminary data, preliminary results were stronger than expected and point to intuitive relationships. The strongest relationship between a driver and the footprint exists between human development (HDI) and urbanization; the relationship (r=-0.48) is inverse (as development rises, urbanization falls).åÊ Conflict Index and Remittances portray the second strongest relationship (r=0.36); as conflict rises, remittances to a country also rise.åÊ Gross Domestic Product per capita with urbanization, is the third strongest (r=-0.35), inverse and significant.

    With no surprise, the relationships strengthen and become more insightful with increased resolution.åÊ At the level of regions (using UNDP breakdown), conflict has a strong link to movement in Europe / North America (with remittances and IDPs, p=0.63), in Asia and the Pacific (also with remittances, p=0.54), Latin America / Caribbean (with IDPs, p=0.47) and in Africa (p=0.34). Even at this crude level, remittances take a new perspective as they are inversely related to movement among the Arab States (as growth rates speed up, economies may be strengthening and remittances fall) and positively related to movement in Asia and the Pacific, and Europe / North America (as conflict rises, more people leave and/or send money home).åÊ Hidden under this difference lies a wealth of knowledge waiting to be explored.

    Since none of the footprint proxies leave in themselves deep tracks, it may also be useful to create a composite footprint index. Evidence is strong that drought is not linearly related with the footprint. It is crucial to acquire and add to the present analysis environmental drivers of adequate quantity and quality.åÊ The most important data enhancement, however, involves bringing the analysis to a higher level of resolution than the current national level described above.åÊ The addition of gridded data sets (for population and climate extremes), the pinpointing of specific regions of reported hazard or conflict events and the use of urban agglomeration rather thanåÊ national data, among other refinements, will all enrich the Global Footprint analysis.

    Expected Results

    Once a full data set is compiled and major geo-temporal trends are identified, the Global Footprint will be used to visualize environmentally-induced migration using geographic information systems. It will then guide a GIS-based micro-simulation exercise (in a gridded environment) to systematically explore the weight of various drivers acting on independent agents within specific yet dynamic contexts of policy, individual perception and capacity. The Global Footprint will reveal important patterns which can be used to identify potential migration ‘hotspots,’ with the clear aim of promoting appropriate policy and facilitating risk management.

    Annex 1: Chronology of events linked to the Environment – Migration Nexus
    Annex 1 Chronology of events linked to the Environment - Migration Nexus

    Lezlie Erway Morini̬re

    Lezlie Erway Morini̬re

    After 18-years living and working in Africa and the Indian Ocean, Lezlie Erway Morini̬re is an Interdisciplinary Doctoral Candidate at the Office of Arid Lands Studies (Minor: Global Change), University of Arizona with prior academic degrees in Epidemiology/Biostatistics and Linguistics. Having grounded her career in early warning (with the FEWS project), Ms. Morini̬re is preparing her dissertation on climate-induced migration, supported by the Stockholm Environment Institute (SEI), Oxford. In a parallel life, she works as an international consultant with the United Nations, NGOs and bilateral / national organizations, she has contributed to the prevention or response efforts of both natural hazards (tsunami, cyclones, floods, drought, locust, and cholera) and complex emergencies (Darfur, DRC, Burundi, Cote d’Ivoire/Mali). She teaches Disaster Risk Science (Andrews and Bahir Dar Universities) and has published most on needs assessment in humanitarian response. Ms. Morini̬re’s extensive field work keeps her feet firmly planted in reality, harmonizing both theory and policy. She lives with her husband and three children in Reunion Island.


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