Study says climate change will make it more difficult for the world’s poorest to migrate

The paper published in Nature Climate Change finds that as the effects of climate change intensify, people will be increasingly affected by “resource-constrained immobility” – meaning they do not have the resources to migrate.

The authors found that in the “medium” emissions scenario, there would be a 10 percent reduction in immigration for the lowest income groups by the end of the century. They added that in the most pessimistic emissions scenario, this figure would rise to 35 percent.

The paper stresses the importance of policy-making to address the challenges faced by populations vulnerable to inertia as well as climate-driven migration.

A scientist not involved in the study tells Carbon Brief that this work supports “[continuing] To further understand the potential plight of those with ‘immobility (international) due to resource limitations’ [and] its consequences.”


As the climate warms and extreme events around the world become more severe, one adaptation strategy is migration to avoid the worst effects of climate change.

In 2020, there were about 281 million international migrants, making up more than 3 percent of the world’s population. People may migrate to escape persecution, in search of economic opportunity, or to join their families abroad. Climate change has accelerated international migration – or out-migration – especially when it is linked to armed conflict.

However, the authors of the new study note that little research has focused on people living in areas threatened by climate change who are unable to migrate due to resource deprivation. They call this “stagnation”.

“Climate change not only affects the aspiration to act, it also affects the ability to do so,” lead author Dr. Helen Benvenist of Harvard’s Center for the Environment told a news conference.

If climate change is negatively affecting people’s ability to migrate internationally safely, orderly and humanely, the social justice effects of climate causing immobility are quite clear.

Fernando Riosmina, Associate Professor, University of Colorado

To assess the scale of this problem, the authors first modeled the movement patterns of people at different income levels to assess how material resources are constrained or encouraged to emigrate. They also modeled the amount of income migrants send back to their home communities from their new destinations.

Then, they embed this model in an Integrated Assessment Model (IAM) to simulate the impact of climate change on resource deprivation and subsequent immobility. This allowed them to project migration—and thus immobility—for every income quintile (every fifth of the income distribution) in 16 global regions for this century.

The authors projected changes in immobility over the next century under five emissions scenarios – known as “representative concentration pathways” (RCPs) – combined with socio-economic scenarios – known as “joint socio-economic pathways” (SSPs).

To determine the impact of climate change on immobility due to resource constraints, the authors ran the model with and without the adverse effects of climate change on the economy, and compared the number of migrants. They investigated both the “fundamental” and “catastrophic” damages from climate change. The latter has been calculated so that the global GDP loss in damages is equal to 50 percent for a temperature increase of 6°C.

The maps below show the change in immigrants from different regions in four different sets of scenarios by the end of the century. The left column shows the ‘average’ SSP2-RCP4.5 scenario, while the right column shows the ‘most pessimistic’ SSP3-RCP7.0 scenario.

The upper and lower maps show, respectively, two climate change damage scenarios; Baseline and catastrophic. Green and pink shading indicates that climate change is increasing and decreasing migration, respectively.

The relative impact of climate change on migrant levels from the bottom quintile of the four emissions and damage scenarios. Source: Benveniste et al (2022).

The authors find that more pessimistic development and climatic scenarios do not lead to immobility of limited resources in a larger number of regions. Instead, the decline in the emigration of the poorest becomes “much larger” for sub-Saharan Africa, North Africa and the former Soviet Union.

For lower-income populations in these three regions, resource constraints from climate change will result in 40,000, 40,000, and 25,000 fewer immigrants, respectively, over the last decade of this century, the authors add.

The research paper found that when catastrophic damages are included, on the other hand, migration from some regions of Asia and Central America increases due to the greater attraction towards more affluent regions of the world. In particular, the paper says that climate change may have an overall “beneficial” economic impact on China into the later part of this century. This has an indirect effect on immigration because individuals will have the resources to move outside the country.

However, the authors say that even then, these populations are able to use these resources to migrate and improve livelihoods in the region of origin through remittances – money sent from migrants to their regions of origin.

money flows

In their model of migration and remittances, the authors looked at how population size and income affect migration.

For example, they found that the ratio of income between countries of origin and destination is an important factor for migration. Higher incomes in the destination area reduce the ‘push factor’ that drives people to leave, while higher incomes in the destination area enhance the ‘pull factor’ that encourages it.

The paper found that regardless of whether the damages are proportional, independent, or inversely proportional to income, the poorest people will experience the greatest damages as a result of climate change.

In the SSP3-RCP7.0 scenario, for example, damages could violate 100 percent of income in North Africa and the former Soviet Union under the assumption of inverse proportions of damages according to income.

The figure below shows the differences between income earned through transfers and income lost through climate change damages in 16 global regions under five emissions scenarios. Negative values ​​on the left indicate that the transfers are insufficient to compensate for the damages.

Migrant remittances

Difference between migrant remittances and climate change-related harm as a share of income for the lowest income quintile for five SSP-RCP scenarios. Source: Benveniste et al (2022).

The authors say remittances from migrants in the lowest-income quintile in regions of origin can help maintain livelihoods where they are widely affected by the damages of climate change. But by mid-century, the poorest in more than half of the world’s regions studied will not be able to offset the damage through transfers even in the average emissions scenario.

In 11 regions – including sub-Saharan Africa, the United States and North Africa – the study found that in the “most pessimistic” emissions scenario of SSP3-RCP7.0, remittances would not offset the damage to the poorest people in this population.

The authors say that even for the “medium” scenario of SSP2-RCP4.5, the damages are greater than the conversions in 10 regions. They added that the loss of resources for these groups may occur as a result of migration caused by climate change.

Implications for “climate justice”

This paper reveals the “potentially devastating” impact of climate change on the world’s poorest communities and proposes the “boundaries” of migration as an adaptation strategy for those affected.

The authors state that this issue “should be of immediate and substantive policy interest”. They urge international institutions and conventions to address the deadlock with a focus on “different local contexts” in terms of their impact on people of different ages and genders.
When asked about the implications of this paper on climate justice, Dr. Fernando Riosmina, associate professor of geography at the University of Colorado at Boulder, who was not involved in the study, told the Carbon Brief:

“If climate change is negatively affecting people’s ability to migrate internationally in a safe, orderly and humane manner and in ways that may benefit migrants […]The social justice implications of the climate resulting in inertia are abundantly clear.”

Similarly, Benveniste tells Carbon Brief that “in terms of policy responses, the actual needs of [immobile communities] It can be said [substantial] As people who end up being displaced due to climate change.”

When asked about the research methodology, Dr. Chi Shu, a professor in the College of Life Sciences at Nanjing University, who was not involved in this research, told Carbon Brief that “while the authors were [consider] A rich set of factors “in simulating inertia,” climatic migrations are still very difficult to predict, as migration also has complex causal links with many other factors.

Dr. Riosmena also says that since the “adverse effects [of climate change] Concentrated particularly among those least connected to pre-existing international migrant networks”, future work could focus on how these networks affect migration behaviors in a climate context.

Additionally, the authors suggest that more research could focus on “internal inertia,” or movement within countries — rather than international gridlock — and the impact that climate change can have.

This story was published with permission from Carbon Brief.

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