The threat of climate-related mass migration may make for good newspaper headlines, but scientific evidence and past experiences indicate that only a minority may be forced to leave their homes as a direct result of climate change. Political, social and economic pressures are likely to have as much effect as environmental change on the displacement of populations in the years to come
The role played by climate in explaining the geography of populations is relatively well known. The first ‘out of Africa’ movement of homo sapiens seems to have occurred around 125,000 years ago when the greening of the Sahara opened a passageway to the Mediterranean shore. More recently, the excessive rains linked to the Irish potato famine in the mid 19th century and the droughts of the 1930s in the plains of the American Dust Bowl were amongst the factors pushing hundreds of thousands of migrants to the USA and into California respectively.
As theories of migration grew in coherence and complexity over the course of the 20th century, climate considerations disappeared almost completely from explanations of population displacements. Migration resulting from environmental factors – called “primitive migration” by Professor William Petersen, one of the most respected migration specialists of the 1950s – was seen as a vestige of man’s historical difficulties in coping with natural forces. These difficulties were expected to disappear as technological progress gradually enabled humanity to gain mastery over nature.
It therefore came as a surprise to migration scholars when, at the beginning of the new millennium, alarming predictions that millions of people could be displaced due to environmental change appeared in the climate change literature. No systematic research had actually been done on the specific topic of migration and climate change and there was – and still is – much vagueness surrounding the concepts employed, the underlying mechanisms involved, the number of people currently or potentially affected and the geographical zones concerned. The alarming predictions nevertheless were soon to be echoed by advocacy groups, the media and international organisations. Popularised by colourful pictures of people fleeing the forces of nature, the figure of the so-called ‘climate refugee’ became the human face of climate change.
What can be said, on the basis of existing scientific literature, about the potential migratory consequences of climate change in the next 50 years? The task is not easy. Climatic factors are rarely the sole cause of migration and the economic, social and political situation of the region under threat can, depending on the case, increase or decrease the flow of migrants. Provided it is done with much caution, the expected consequences of climate change can nevertheless be compared with past experiences of natural disasters so as to evaluate the possible resulting migration flows.
Three consequences of climate warming forecast in the latest report of the Intergovernmental Panel on Climate Change appear to be the most threatening: the increase in the strength of tropical cyclones and in the frequency of heavy rains and flooding; the growth in the number of droughts; and the rise in sea levels resulting from both water expansion and melting ice.
The consequences of cyclones and floods on population displacement are among the easiest to identify in that they manifest themselves in a brutal and direct manner. While we know approximately the number of persons affected by flooding worldwide (99 million each year between 2000-08), and by cyclones (39 million), the total number of people threatened by an increase of these kinds of disasters remains very difficult to estimate. No climate model is able to predict with accuracy whether or not the affected zones – situated mainly in the tropics – will be densely populated and whether the damage wrought will have tragic consequences.
Apart from the difficulty of forecasting, the studies carried out after such events tend to relativise their effects in terms of migration in general, and long-term/long-distance migration in particular. Living mainly in poor countries, the victims have little mobility and the majority of the displaced return as soon as possible to reconstruct their homes in the disaster zone. The results from numerous studies conducted worldwide tend to confirm this point with remarkable regularity. On a global level, the general conclusion therefore is that the potential of hurricanes and torrential rains to provoke long-term and long-distance migrations remains limited.
Case studies bring to light contrasting images of the consequences of water shortages for migrations. On the one hand, there are many well-known cases of mass population departures following droughts, in particular in Africa (with an impressive figure of one million displaced persons during the drought in Niger in 1985) but also in South America, the Middle East and Central and Southern Asia. On the other hand, many researchers strongly minimise the direct link existing between drought and migration by highlighting that the latter often constitutes the last resort when all other survival strategies have been exhausted. For example, during the 1994 drought in Bangladesh, only 0.4 percent of households had to resort to emigration.
Other researchers hold similar views to the Nobel Prize winner for Economics, Amartya Sen, who noted that famines are, in general, only marginally the direct result of environmental factors, but much rather of political ones, and that this multi-causality also holds for migrations. The general conclusion is that forecasts of increased migrations linked to drought-related phenomena remain hazardous. Although the risk exists, it would be difficult to put a figure on the magnitude of populations at risk and the eventual number of migrants arising from global warming induced droughts.
While the first two hazards may not necessarily lead to massive population displacements due to climate change, the potential for migration when linked to an increase in sea level is considerable. Unlike cyclones, rains and droughts, the effects of this phenomenon are virtually irreversible and this could make migration the only option for affected populations. Pinpointing areas that are vulnerable to the consequences of rising sea levels is a relatively easy task because the configuration of coastlines, their altitude and population are well known and thus easy to map. Hence, it is possible to calculate, on a global scale, the number of people living in low elevation coastal zones and threatened by rising water levels, higher tides or further-reaching waves.
On the basis of the most recent estimates of the consequences of climate change, it seems reasonable to consider as being directly vulnerable by the next century, the 150 million people living at an altitude of less than 1 metre. Of whom, 75 percent live in the major river deltas and estuaries in South Asia (the Indus and Ganges-Brahmaputra) and East Asia (the Mekong, Yangtze, and Pearl River). Although far less populated, certain islands such as Tuvalu or the Maldives are the most immediately threatened in the short term, as they are situated only centimetres above sea level.
Climate change clearly has the potential to generate migration flows but – unless we completely fail to moderate our behaviour they will only progressively manifest themselves over the centuries ahead, with the exception of the flooding of certain islands. The impact of increases in droughts and other meteorological disasters predicted by climatic models will remain regional and short-term rather than international, and is at present difficult to estimate.
Existing research shows that due to the number of factors involved, no climatic hazards inevitably result in migrations. Many authors note that even if disasters become more frequent in the future, political efforts and measures of protection will be able to lessen the need to migrate provided that the necessary financial means are made available. Even rising sea levels could be partially counteracted by the erection of dykes or the filling in of threatened zones.
In that context, the question of what kind of international system of protection to put in place to face these challenges remains unanswered. Some have called for the inclusion of environmental motivations in the international definition of refugees, but it seems more crucial to improve the general humanitarian framework of emergency assistance and the burden-sharing mechanisms to mobilise the financial resources needed for adaptation than to focus too narrowly on the sole case of displaced populations. Although they might be the most visible among the victims of climate change, migrants will remain a minority.
