Environmental hazards affect populations worldwide and can drive migration under specific conditions, especially in middle-income and agricultural countries. According to a new study, changes in temperature levels, increased rainfall variability, and rapid-onset disasters such as tropical storms play an important role in this regard.

Environmental migration is most pronounced in middle-income and agricultural countries and weaker in low-income countries where populations often lack the resources needed to move away. The findings of the study by the Potsdam Institute for Climate Impact Research (PIK), IIASA, the Vienna Institute of Demography of the Austrian Academy of Sciences, and the Vienna University of Economics and Business, make it possible to identify geographical regions that may be especially susceptible to migration movements in the future.

“Environmental factors can drive migration, but the size of the effects depends on the particular economic and sociopolitical conditions in the countries,” explains lead author Roman Hoffmann from PIK and the Vienna Institute of Demography of the Austrian Academy of Sciences. “In both low and high income countries, environmental impacts on migration are weaker – presumably because either people are too poor to leave and therefore essentially become trapped, or in wealthy countries, they have enough financial means to absorb the consequences. It is mainly in middle-income regions and those with a dependency on agriculture that we see strong effects.”

The meta-analysis study, which analyzed 30 previously published studies on the topic, reveals a number of interesting patterns. It shows, for example, that impacts on migration vary by types of environmental  hazards and that different hazards can reinforce each other.

“While changing temperatures in a region are found to have the strongest impact on migration, rapid-onset disasters, and rainfall variability and anomalies can also play a role. Especially smallholder farmers rely on steady climatic conditions and suffer from changes and shocks as they have insufficient capacities to adapt,” comments coauthor and Deputy IIASA World Population Program Director, Raya Muttarak, who is also affiliated with the Wittgenstein Centre for Demography and Global Human Capital (IIASA, VID/ÖAW, University of Vienna).

The researchers emphasize that there is no automatism at play – environmental migration always depends on a number of economic and sociopolitical factors. The narrative of climate refugees pushing towards Europe or the US may be too simplistic. For instance, the researchers found compelling evidence that environmental changes in vulnerable countries predominantly lead to internal migration or migration to other low- and middle-income countries rather than cross-border migration to high-income countries. Affected populations often migrate to places within their own region and eventually return to their homes within a relatively short period of time.

The findings, which have been published in the latest issue of Nature Climate Change, also hint at regions that are highly vulnerable to climate change where environmental migration may be particularly prevalent.

“Our research suggests that populations in Latin America and the Caribbean, several countries in sub-Saharan Africa – especially in the Sahel region and East Africa – as well as Western, Southern and Southeast Asia are particularly at risk,” says coauthor Anna Dimitrova from the Vienna Institute of Demography of the Austrian Academy of Sciences.

Given the expected rise of global average temperatures, the researchers believe that the topic of environmental migration will become more important in the future. Consequently, interventions have to be tailored to the actual situations on the ground that support affected populations and reduce vulnerabilities.

“The best way to protect those affected is to stabilize the global climate by rapidly reducing greenhouse gas emissions from burning fossil fuels as well as simultaneously enhance adaptive capacity such as through improving human capital,” says Jesus Crespo Cuaresma, a researcher with the IIASA World Population Program and professor of Economics at the Vienna University of Economics and Business. “While migration can be an effective adaptation strategy for households, it can be involuntary and could come with non-negligible consequences both for the migrants, their household members, and people at the place of destination.”

Adapted from a press release by the Potsdam Institute for Climate Impact Research (PIK).


Hoffmann R, Dimitrova A, Muttarak R, Crespo Cuaresma J, & Peisker J (2020). A Meta-Analysis of Country-Level Studies on Environmental Change and Migration. Nature Climate Change DOI: 10.1038/s41558-020-0898-6


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