Some countries, in Asia in particular, would undoubtedly be profoundly affected by a significant rise in sea level because of the large proportion of the population living in low-lying coastal areas. But unless the most pessimistic warming scenarios come true, is it inconceivable to imagine that humans could simply adapt to a rise in water levels of a few millimeters per year? Also, at this rate, some countries will continue to gain as much surface area through sedimentation as they lose through erosion. The drowning of Bangladesh, one of the world's most densely populated areas, is a fragile hypothesis: it does not take into account the contribution of sediment carried by Himalayan rivers, which will more than compensate for the rise in sea level. This is caused as much by subsidence of the earth as by global warming. Subsidence can be natural (i.e. for volcanic islands, for instance) or caused by human activities such as the destruction of natural barriers, the construction of infrastructures, or the depletion of water tables. Large cities such as Bangkok, Ho Chi Minh City, Jakarta or Manila tend indeed to "sink".
It is thus not surprising that a review of the scientific literature does not allow for a clear conclusion on the quantitative effect of global warming on future migration.
Some of the figures put forward have no serious scientific basis. Biologist Norman Myers famously estimated in 1993 that there could be 200 million climate refugees by 2050. This projection merely counted the number of inhabitants of low-lying coastal areas. It has since been repeated by numerous publications and official speeches without any critical perspective. One even often finds reference to the figure of more than one billion climate refugees by the middle of the century: here again, it comes from a report that simply counts the inhabitants of the most vulnerable areas of the planet.
Some experts do see a causal relationship between global warming and the increase in asylum applications in Europe, and predict that by the end of the century these applications will increase by between 28% (+98,000 per year) and 188% (+660,000 per year). But they also blandly acknowledge that their projections on asylum applications in European countries "assume that the relationship we uncovered between 2000 and 2014 is going to remain unchanged for the next 80 years". Hence the relevance of scenario-based analysis. The series of World Bank studies produced the following data: water scarcity and sea level rise in the developing world are likely to generate the internal displacement of 78 million people by 2050 in a positive scenario, and 170 million in a negative one.
Finally, let's listen once again to what the IPCC says at the end of its review of the scientific literature: migration, far from being systematically a tragedy, can be a good adaptation strategy that can reduce risks in very vulnerable places; and some local climate changes can be associated with an increase in agricultural productivity, and thus reduce migration flows.
In the end, the expression "climate refugees" raises questions about both its relevance and its seriousness: about its relevance, since migration is multifactorial and this category covers disparate population movements, sometimes with no link to global warming; about its seriousness, since the displacements it seeks to describe are generally local, limited and reversible, and the gloomiest forecasts do not take account of the adaptation of human societies.
Copyright: ORLANDO SIERRA / AFP
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