A study by the World Bank predicts that millions of people in sub-Saharan Africa will have to leave their homelands because of climate change. We have spoken with, Jacob Schewe, one of the authors
Jacob Schewe is a physicist at the Potsdam Institute for Climate Impact Research. He is one of the managers of the project, ‘Climate Change Impacts on Migration and Urbanization’, financed by the Leibniz Association. His research visits have taken him to such places as the USA, Israel, Palestine, Spain and India.
We have calculated the possible impact of climate change on migratory movements within a region and have combined models from the areas of climate, agricultural productivity, water resources and population development to this end.
What have you found out?
We looked at South Asia, Latin America and sub-Saharan Africa and played through various scenarios for the year 2050. In the best scenario, with ambitious climate protection and inclusive social and economic development, we see an increase in internal migration in these three regions of about 30 million people compared to a world without climate change. In the worst case scenario, that is, with unmitigated climate change and great social inequality, this number rises to about 143 million people.
Regarding agriculture, the conditions in a warmer world are becoming increasingly difficult
How will climate change affect sub-Saharan Africa?
Regarding agriculture, the conditions in a warmer world are becoming increasingly difficult. Particularly the current dry regions of the world like sub-Saharan Africa will experience more extreme weather. As far as water resources are concerned, it is relatively difficult to make predictions.
How so?
We still cannot make reliable predictions because we still cannot simulate atmospheric circulation in the tropics within some regions well enough. The carbon dioxide level in the air also has ambiguous effects: On the one hand, it is important for the metabolism of plants. A higher CO2 level in the air can reduce the need for water and thus even help the plants initially. On the other hand, a higher carbon dioxide level is the biggest driver of climate change, which has far more negative effects such as droughts.
Are there any regions that will experience more precipitation?
We see in some climate models that as a result of climate change, the West African monsoon moves north inland and the Sahel region receives more precipitation. This is why one must consider more closely how to potentially deal with this precipitation, whether there will be more flooding or how to expand water storage. A warmer atmosphere can hold more moisture. So when it rains, the rainfall becomes more extreme. Nevertheless, droughts develop faster and last longer because the water evaporates faster.
What effects are still to be expected?
Increased rainfall changes agricultural productivity. We have used models that simulate plant growth of the most important crops over the year. Depending on the stage of growth, a plant may benefit from or be destroyed by precipitation.
Can the changes in the climate of Sub-Saharan Africa be determined already?
Yes, but until recently it has been difficult to distinguish whether they have been caused by man-made climate change or whether they are due to natural fluctuations. For example, in the 1970s and 1980s major droughts were found in the Sahel. The region is now becoming wetter on average and has been for some time. At first glance, this is clearly good news. Whether this is caused by natural fluctuations or whether the system will continue to produce more rainfall in the future, we do not know for sure yet.
We must make a distinction between two factors: climate change on the one hand, and the vulnerability of populations and their countries on the other
But does man-made climate change exist?
For sure, yes. In the past 100 years, we have seen an increase in temperature of just under one degree worldwide. The problem is that our series of measurements do not go back that far, especially in many African countries. With regard to many regions and variables, it is therefore difficult to separate climate change from natural, local fluctuations based solely on existing data. Nevertheless, we know that as there is more severe heat, severe precipitation increases - regardless of whether this can be observed now or not, because we know the context behind it.
Which regions in Sub-Saharan Africa are particularly affected by climate change and the resulting food insecurity?
We must make a distinction between two factors: climate change on the one hand, and the vulnerability of populations and their countries on the other. The climate will change in all the tropics, but to assess the effects one has to look at which countries have relatively poor populations or are heavily dependent on agriculture. The countries in the Sahel already have difficult climatic and also social and political conditions. Countries such as Sudan, Chad, Niger and Mali are unlikely to be able to adapt readily to the new conditions.
Will climate change in this region increase hunger?
This is not easy to answer. To know this, you have to look at many factors: from the climate and agricultural productivity to political management. Since hunger is not just climate-related, but can also stem from poor planning and bad management, it is therefore also man-made.
Jacob Schewe is a physicist at the Potsdam Institute for Climate Impact Research. He is one of the managers of the project, ‘Climate Change Impacts on Migration and Urbanization’, financed by the Leibniz Association. His research visits have taken him to such places as the USA, Israel, Palestine, Spain and India.
Potsdam Institute for Climate Impact Research (PIK)
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