Climate Change and Mass Migration

by Ethan Lewis

An African Independent writer from the Washington Post investigated the large scale issue of mass human migration stemmed from climate change. The writer met with ANM Muniruzaman, a Bangladesh Politician, who recently attended an international migration policy meeting and said “The international system is in a state of denial.” He then continued to say “If we want an orderly management of the coming crisis, we need to sit down now.” Displacement of humans due to climate change is already ongoing with natural disasters like droughts, floods, and storms. Saying exactly how many people will have to migrate in the future is difficult, but statistics from previous years can help form an estimate. Roughly 203 million people were displaced between 2008 and 2015 due to natural disasters. Continue reading

Adapting to Climate Change Through Migration

by Becky Strong

In 2006, Robert McLeman and Barry Smit from the Department of Geography at the University of Guelph wrote an article investigating migration as a possible adaptation to climate change, presenting conceptual models, and discussing the migration patterns of people from Eastern Oklahoma in the 1930s. Citing sociology, geography, and other social science sources. They examined theories of human migration behavior and analyzed concepts such as vulnerability, risk exposure, and adaptive capacity all theories developed within the climate change research community. While there is notable historical evidence linking human migration and climate change, it is not considered an automatic response and is influenced by many different factors. This notion can be traced back to Hippocrates and Aristotle who believed that humans determined the habitability of an area based on the characteristics of the natural environment and that they were shaped by these characteristics. Continue reading

Human migration and agricultural development due to sea-level rise likely to cause biodiversity loss

Previous studies of the impacts of sea level rise (SLR) on human inhabitance patterns and terrestrial biodiversity have focused mainly on primary effects, which include land area loss due to inundation and erosion in coastal areas. However, secondary effects, or the ecological impacts of human displacement and relocation from low-lying areas because of primary effects, are very important when considering biodiversity loss. Wetzel et al. (2012) examined the impacts of secondary effects on biodiversity in the Southeast Asian and Pacific (SEAP) regions and found that in many cases secondary effects may dominate range loss. In the predicted levels of SLR, 4–27% of the human coastal population (2-52 million people) will be forced to relocate. Human migration will be especially pronounced on the Indo-Malaysian islands, where 4–28% of the population will be forced to migrate, and 30% of the inundated land will be urban and intensive agricultural land. This relocation, as well as the increase in natural land conversion to agricultural and urban land in the hinterlands will likely cause significant population declines in many species.–Olivia Jacobs
Wetzel, F.T., Kissling, D., Biessmann, H., Penn, D.J. Future climate change driven sea-level rise: secondary consequences from human displacement for island biodiversity. Global Change Biology 18, 2707–2719. [GSSS Wetzel kissling secondary]

                  Wetzel et al.(2012) studied the potential effects of sea level rise (SLR) on more than 1,200 islands in the Southeast Asian and Pacific region (SEAP). They further divided this area into three broad categories, Australia, Oceania, and Indo-Malaysia, and used Digital Elevation Model (DEM) data to map potential SLR scenarios. The three scenarios addressed were 1 m, 3 m, and 6 m of total SLR, which are values that represent the most common estimates of SLR for this century and higher ones for the coming centuries. Using these maps of SLR, the scientists analyzed primary effects on coastal areas by estimating the inundated and eroded area in the coastal zones. Secondary effects, or the land converted from natural habitat to agricultural or urban areas due to population migration, were estimated by using mammal distribution data for 54 species on 109 Indo-Malaysian islands. Each mammal was analyzed individually using information from previous studies. Notably, the scientists also assumed that there was an equal-area land-conversion of inundated urban and intensive agricultural areas in the hinterlands.
                  The data indicate that primary effects will result in a large loss of coastal zone in the SEAP region. On average, 3% of land area in the SEAP will be inundated from the 1 m scenario, and 32% will be lost in the 6 m scenario. This will cause an estimated 8–52 million people (or 4–27% of the total population) to migrate to the hinterlands. Further, the Oceanic area will be most vulnerable to inundation, with an estimated 7–46% loss for the 1–6 m scenarios. Australia will be less affected, experiencing a land area loss of 2–25% in these scenarios, and Indo-Malaysia will experience a land loss of 4–35%. In these inundated areas, about 30% of the lost area is urban and intensive agricultural land in Indo-Malaysia and 4–28% of the population will be forced to migrate, whereas only 2–6% of the population in Oceania and Australia will be at risk. These data indicate that biodiversity loss due to secondary effects will be most pronounced in Indo-Malaysia and primary effects will dominate elsewhere.
                  Secondary effects are especially important when considering biodiversity because areas with large coastal urban populations and agricultural development, such as Indo-Malaysia, will experience large amounts of human migration and land conversion. Range loss due to secondary effects was greater than loss due to primary effects in Indo-Malaysia for 22–46% of species in maximum range loss scenarios, while 9% of species are only vulnerable to secondary effects. The authors also note that different species in similar island scenarios respond very differently to primary and secondary effects. The Smokey Flying Squirrel has a projected range loss of 1–3% due to primary effects, but a loss of 2–60% from secondary effects. Comparatively, the Rajah Sundiac Maxomys may experience primary loss of 1–15%, while secondary effects play a lesser role in range area loss. Thus, in some instances secondary effects will dominate species range loss, while secondary effects will not contribute significantly to that of other species. The effects are dependent on both region and species.
                  This study makes some key assumptions that could contribute significantly to a change in the aforementioned estimates. It ignores the expected temperature and precipitation changes due to climate change, and it also only analyzes the secondary effects on mammals on the SEAP islands. The model may also be overly conservative because it only considered the most intensive farming types, did not consider other ecological interactions such as interspecific competition due to coastal species migration, and did not include the worst-case and more liberal estimates of SLR. However, the study still provides further evidence that SLR anticipated from global warming will have many major consequences for biodiversity, and it expands our understanding of biodiversity loss to include the impacts of secondary effects due to SLR.

Economic or Environmental Migration? The Push Factors in Niger

This paper examines the question of whether humans migrate for purely economic or environmental reasons. Although it is known that both factors impact human behavior, the complex decision calculus of humans makes it complicated to ascertain dominant causes for migration. In Niger, the poorest country out of a list of 182 on the Human Development Index, several important environmental push factors impact life: droughts, soil degradation, the shrinking of Lake Chad, Niger River problems, deforestation, and sand intrusion. These push factors are caused by climate change, regional ecological features, and human activity in the area. The authors of the study concluded that economics was the mechanism through which environmental impacts were felt by migrants, prompting the recommendation of the term “environmentally induced economic migration” to refer to the situation in Niger. –Adriane Holter
Afifi, T., 2011. Economic or Environmental Migration? The Push Factors in Niger. International Migration published ahead of print May 19, 2011,doi:10.1111/j.1468-2435.2010.00644.x

          The sustainability of the environment is a security threat to the estimated 14 million people who live in Niger, because they rely on stable ecological conditions to maintain their livelihoods. With an economy that relies on subsistence crops, livestock, and uranium deposits, Niger’s general population is at risk for destabilization due to rapid climate change. Studying the relationship between the environment, land, and the economy helps develop a more complete picture of the factors that contribute to migration in Niger.
          To study the ways in which economy and environment interact, the Niger researchers combined a study of declining conditions with questionnaires, interviews, and phone calls to experts and migrants in affected areas. For the questionnaires, researchers polled 60 migrant and 20 non-migrant persons in a 2008 field visit to the regions of Niamey and Tillabeeri. Respondents to the research questionnaires revealed that: 90% migrated in part to some environmental consideration, 70% expected future environmental problems to impact them, 50% would migrate for or are currently planning to leave their homes for environmental reasons, and 80% would return to their homes if environmental conditions allowed. Although many of the people the researchers studied did not initially indicate the environment as the main cause of their departure, further examination revealed that economic rationale for migration had a root in environmental issues. For instance, the dwindling water for farmers and herders near Lake Chad directly impacted their economic security and therefore supplied a possible reason for moving. Thus, the term “environmentally induced economic migration” becomes valuable for conceptualizing the real world impacts of climate change.
          Environmentally induced economic migration is a more permanent, uncontrollable situation than the historic cultural practice of seasonal migration in Niger. Furthermore, environmentally induced economic migration induces changes in social dynamics e.g. the organization of food source cooperatives and the selling of labor. Males in some regions depart during the dry season, leaving women and children to undertake the majority of work related to environmental problems. To help counter the social, economic, and security burdens of the people, the researchers recommended several courses of action including: development policies that prevent further environmental degradation, investment in the development of eco-friendly jobs, education campaigns for children and adults, emphasis on indigenous means of coping with environmental security threats, humanitarian aid for people living in abandoned regions, intensification and broadening of the President’s Programme, and increased attention to the re-integration programme started by IOM Niamey for migrants motivated by the environment. 

Soil Quality and Human Migration in Uganda and Kenya

The issues of soil quality impact on humans and environmental migration have been highly debated in the scientific community. However, studies previously conducted on these issues have lacked a large-scale program to monitor soil-degradation. Furthermore, no study has examined economic or social concerns about soil quality outside of agriculture. With the intention to correct these oversights, Gray et al (2011). sought to measure how soil quality impacts internal migration from grain-producing households in the East African Highland countries of Uganda and Kenya. The results of the study show that out-migration from these counties declined with soil quality. Soil quality in Kenya was particularly relevant for migration in small farm households. In Uganda, there was an increase in marginal migration with soil quality, which is consistent with the poverty trap of migration where rural population is large and access to agricultural resources is limited. The authors of the study see their work as a necessary consideration for development policy in Kenya and Uganda. –Adriane Holter
Gray, Clark L., 2011. Soil quality and human migration in Uganda and Kenya. Global Environmental Change 21, 421— 430

          To implement their study, Gray et al. used a longitudinal survey dataset with information collected through the Research on Poverty, Environment, and Agricultural Technology (REPEAT) project. This dataset contained information on migration and soil properties for 1200 households. From this information, the researchers created a household-level measure of soil quality as well as the rate that single persons undertook either temporary or permanent migration. A model of possible random effects tested the effect that soil quality had on migration with a control for household variables.
          In Kenya, soil quality had a negative effect on migration. The likelihood for temporary labor migration was 67% lower and permanent labor migration was 42% less likely to occur when soil quality was high. Researchers found that women or married individuals were the most likely to undertake both temporary and permanent non-labor migration. This result is significant because it highlights how responses to soil degradation have gendered manifestations in society. Multiple attachments to several households as a result of marriage helps explain the increase in migration for married individuals. Additionally, migrants were stratified by age with the largest amount of movement occurring between 25 and 29-years-old except for permanent labor migration, which peaked between 35 and 49-years-old.
          Since Uganda had a smaller sample size than Kenya, the results from the study are not as dramatic. Nevertheless,  research in the country found that soil quality had a marginally positive effect on migration, especially for permanent non-labor migration. There was no clear gender divide for migration, but like Kenya age was also an issue in Uganda with temporary and permanent labor migration peaking between 30 and 34-years-old. Temporary non-labor migration was not affected by age. Also like Kenya, the likelihood of migration increased for married individuals. Importantly, individuals in both countries were less likely to migrate if they had been educated. This information reveals the socio-economic advantage afforded to the educated in the realm of migration, signaling a class-based element of the issue. Additionally, non-labor migration increased with a large number of inhabitants in a household and when the household owned large parcels of land. These results reflect the interplay of resource holdings with the need for human movement to sustain household livelihoods at a desired level. 

Drought and Other Driving Forces behind Population Change in Six Rural Counties in the United States

Although population change in the United States has been widely researched, most studies have focused on social and economic reasons for population shifts. The research that does exist on environmental factors for the most part has looked at temperature and seasonal relationships. To provide more depth to known impact of environment on US population shifts, Maxwell et al. (2011) set the primary research goal of identifying the main reasons for population shifts in six counties in three geographic regions. Secondarily, the researchers were interested in finding the relationship between drought from the 1800s to the present and population change. Furthermore, the study sought to assess the spatial variability between the six locations in the study. The study found that traditional variables for population changeunemployment, education, technological advancement, etc.had the largest impact on population change. Through correlation and regression analysis drought was determined to cause a small variance in population change with significance in three of the six counties. Spatially, without other measures of climatic variables, counties in the same region tended to experience similar results. –Adriane Holter
Maxwell, Justin T., Soule, Peter T., 2011. Drought and Other Driving Forces behind Population Change in Six Rural Counties in the United States. Southeast Geographer 51, 133 – 148

The three regions observed in the study were: the Southeast, Ohio Valley, and Great Plains. The counties within these regions shared similar urban structures and economic makeups. All counties were predominately rural and agricultural. Studied counties did not have a metropolitan center, a highway that passed through the region, corporate owned farms, or substantial irrigation. Per capita income, agricultural prices, and manufacturing prices were acquired from census data and adjusted for inflation in order to analyze economic elements of population change. Additionally, variables such as birth and death rates, educational attainment, and unemployment were standardized by country population in the same year for use in developing a full social picture of each county. Climatic variables were retained from the National Climatic Data Center from 1985 to 2000. Drought was quantified through the study of tree rings in the Palmer Drought Severity Index (PDSI), which included an 11-year moving average to account for the extreme yearly variations in temperature and moisture. A multiple regression model was used to analyze which factors were the biggest drivers for population change in each county.
          In the Southeast, the primary drivers for population change in Sampson County, North Carolina were manufacturing value with other significant factors in agricultural and educational sectors. In Bedford County, South-Central Tennessee the primary drivers were college attainment and temperature, with secondary influencers of agricultural value, manufacturing value, and high school attainment. Drought had a significant impact on population change, while population was inversely related to temperature. Increased level of educational attainment indicated an increase in population. In this area, the intuitive tie between drought and agriculture is evident lower amounts of moisture negatively affect crops.
          In the Ohio Valley, Adams County in Northeast Indiana the most successful model for population change included high school attainment, PDSI, and the death rate. Converse to the findings in the Southeast and Ohio Valley, Pottawatomie County, Northeast Kansas in the Great Plains had a negatively correlated relationship between college attainment and population. Similar to Adams County, PDSI has a significant impact on population change in Pottawatomie. Also in the Great Plains, Tillman County, Southwest Oklahoma had the key population change drivers of high school attainment and death rates with birth rates, college attainment, and annual income also possessing a strong influence. Finally, population change in Douglas County in southeastern South Dakota was most strongly linked to high school attainment and birth rates. Like Tillman County, the levels of death rates, college attainment, and annual income were also important factors.
          The fact that population changes in three of the six counties researched in this study were positively related to the availability of moisture signals the need for more research in the relationship between drought and population size. Currently in the United States, the Southeast and the Southwest have the highest rate of population growth in the country. Furthermore, many of the counties in these regions still rely heavily on agriculture. With the increase in climate change, it is likely that droughts will become more frequent and intense today than the measures found in this study. The relationship between drought and threats to agricultural sustainability make these field a crucial realm of research.

When Nature Rebels: International Migration, Climate Change, and Inequality

By combining economic models with environmental knowledge, the authors of this study sought to create an analysis of international human migration that encompassed policy responses to the issue. A two-country overlapping generations model with endogenous climate change measured on a scale of steady state perspective was used to accomplish this end. The authors summarize their main findings as follows: change in climate creates an increase in migration, small levels of climate change result in substantial impacts on the number of migrants, northern immigration policies have the potential to impact long-run migration thus impacting regional inequality, and finally that green technology decreases emissions and long-run migration where the migrant impact to climate change is significant. A consideration of how values of inequality, wealth, environment, and migration numbers impact policy development is also widely discussed. Although the authors caution the limitations of their approach, they ultimately advocate that their model may provide states with guidelines for how to best distribute tax revenue in regard to the issue of human migration. –Adriane Holter
Marchiori, L., Schumacher, I., 2011. When nature rebels: international migration, climate change, and inequality. Population Economics 24, 569600.

          In an environmental review, the authors remind that while the developed world is responsible for the vast majority of CO2emissions, it is the developed world that will experience 80% of the lived damage of global climate change. These experiences include areas such as the loss of agricultural productivity and water quality, which result in unsustainable living conditions, that oftentimes lead to environmentally motivated migration. Reasons for movement out of an area also may include anticipation of deteriorating and therefore non-sustainable living conditions. The economic model used in the study incorporates concerns of livelihood by presenting a decision calculus that states when a person (referred to as “generations”) considers the benefit of migration to be greater than that of staying at home, then that person will migrate. The firms in the model are stated as operating on the basis of profit maximization in a perfectly competitive market where they have access to international capital mobility.
          The authors present four propositions that result from their analysis, many of which have important policy implications. First, the optimization consideration of firms and the relative situation of the generations, an integrated approach is similar to one of autarky, indicating the economic independence of the firm. Second, endogenous climate change is a large contributor to international migration that effectively diminishes the per capita welfare of both northern and southern regions. Third, increased allocation of funds toward border controls reduces southern access to migration and increases northern control. This relationship has the ability to either exaggerate or lessen current north-south regional inequalities due to environmental improvements and long-run migrant numbers. Finally and similar to the third proposition, an increase in taxes allocated to green technology will potentially decrease migrant numbers, positively impact the environment, and alter the relationship between north-south inequality.
          Based on these propositions, the authors posit that it is advisable for Europe to increase the allotment of tax revenue toward immigration costs than North America. Conversely, North America should invest more tax revenue in green technology than Europe. This inverse economic relationship is due to the fact that production in North America creates substantially larger numbers of CO2 emissions than its European counterpart and therefore may best benefit from new environmental policy. Additionally, North America currently employs harsh restrictions on border control policy. Europe’s comparatively “soft” immigration policy therefore makes new approached recommendable.