The following essay was originally compiled for the Mixed Migration Review 2020 and has been reproduced here for wider access through this website’s readership.
The essay’s author Chris Horwood is the Director of Ravenstone Consult and independent consultant.
Many cities are already facing significant exposure to climate change impacts and will continue to do so. Beyond the irony that many climate-induced migrants face new climate threats in the cities where they come to seek refuge and opportunities, in the absence of effective national or international responses it is evident that cities will predominantly have to keep finding their own solutions.
As they are for the majority of those on the move, cities are also magnets for climate -induced migrants and refugees. Climate change and environmental impacts such as increased rainfall intensity, storm surges, flooding, rising sea levels, reduced groundwater, drought, and urban heat islands are already affecting many urban systems worldwide. Two-thirds of the world’s megacities are in regions that are vulnerable to the impacts of climate change, but not all cities—and not all parts of any given city—are affected equally. Where migrants and refugees live and work in cities will often define the level of impact and their vulnerability to climate change. But what options do they have? This essay explores these issues and offers a review of what is being done at the international as well as municipal level to address them. What might the future look like in relation to urban climate change impacts and migration? To what extent— in terms of resilience, adaptation, and mitigation—will we witness a new era of dysfunctional nations being eclipsed by the rising power of cities?
Magnets for climate-induced migrants and refugees
Flows of migration and forced displacement, both internal and international, now almost exclusively head to cities. Urban centres and cities are the destination of choice for almost everyone on the move for whatever reason. For the millions who are forced to move because of weather-related events, causal attribution appears clear cut: “nearly 1,900 disasters triggered 24.9 million new displacements across 140 countries and territories in 2019 […] three times the number of displacements caused by conflict and violence.” People are twice as likely to be displaced by a disaster now than they were in the 1970s.
For many of the others on the move, the reasons for movement—the drivers and compulsions to relocate— are often directly or indirectly intertwined with climate shocks and stressors. As the predicted impacts of climate change and other environmental factors start to bite, this is increasingly the case. Nevertheless, the “multi-causal understanding of migration prevalent in contemporary scholarship has become widely accepted, as has the idea that—given the tangle of factors playing out in migration processes—it is almost impossible to point to individuals or populations whose mobility is determined solely by environmental change.”
Without explicitly or exclusively identifying environmental factors (and their close companion, resource scarcity), studies of “root causes” of migration and forced displacement show environmental issues to be important factors, but to varying degrees. “The nexus climate–migration is increasingly understood as a matrix of mobility responses characterised by different combinations of voluntariness, aims, geographical scope and duration.” Environmental stressors are characterised as acting as a threat multiplier, causing tipping points or acting as triggers not only in complex geopolitical situations, but also in the decision-making processes that lead people to move.
In 2015, the UN Refugee Agency stated that “both the sudden and slow onset impacts of climate change are expected to increase internal and cross border displacement of people and affect human mobility strategies.” In other words, climate factors have already played a significant role in mobility and are expected to continue to do so. “Environmental, economic and political degradation are connected—though the categories are permeable.”
For refugees, resource scarcity and resource competition exacerbated by climate change can play a strong contributory role in the conflicts they are forced to flee. In 2007, then UN secretary-general Ban Ki-moon described the conflict in Sudan’s Darfur region as the world’s first climate change conflict. There have been claims, albeit disputed, that the Syrian war was triggered by climate impacts. While climate change does not directly cause armed conflict, analysts agree that it may indirectly increase the risk of conflict by exacerbating existing social, economic and environmental factors.
For international migrants, environmental changes and loss of rural livelihoods contribute to an economic context that pushes them across borders. Climate change, and the resulting unsustainability of farming and grazing as livelihood options, have for some time become the leading causes of internal mobility from rural areas towards cities in Africa and Asia.
The face of urban climate change impact
To what extent are cities currently affected and expected to be affected in the future? And how will this affect migrants—whether internal or international—living in cities, who in many cases may have moved to urban areas to escape the effects of climate change and environmental shocks and stresses in rural areas in the first place? The Intergovernmental Panel on Climate Change (IPCC) has stated that rapid urbanisation and rapid growth of large cities in low- and middle-income countries “have been accompanied by the rapid growth of highly vulnerable urban communities living in informal settlements, many of which are on land at high risk from extreme weather.” Furthermore, according to C40—a network of megacities committed to addressing climate change—many key and emerging global climate risks are concentrated in urban areas. “70 percent of cities are already dealing with the effects of climate change, and nearly all are at risk. Over 90 percent of all urban areas are coastal, putting most cities on Earth at risk of flooding from rising sea levels and powerful storms.” Additionally, many cities are affected by higher average temperatures exacerbated by the heat-island effect, droughts, and the impact of drier weather on the lakes and rivers that serve them.
Taking urban water as an example, groundwater supplies are under stress due to decreasing precipitation rates and increasing volume of extraction, not to mention increased industrial, agricultural and household pollution. Extreme water shortages increasingly affect cities such as New Delhi, Los Angeles, Cairo, Cape Town, Amman, and São Paulo, and hundreds more. The World Bank suggests that in the second half of this century, many of the people who came to Ethiopia’s capital, Addis Ababa, will be forced to move again and leave the city as local agriculture around it dries up and food shortages start to bite. In Lima, Peru, with its almost 10 million inhabitants, water supply is irregular, and a fifth of the population is cut off from the drinking-water network. Sana’a in Yemen, widely predicted to be the first capital to completely run out of water in the next decade, currently provides less than half its population with piped water; the rest get water through private tankers, costing 5-10 times more. Purchasing water at inflated prices is increasingly common for those in the poorest areas of cities, including migrants and urban refugees. In Jordan, one of the world’s most arid countries, water consumption has reportedly surged by over 20 percent due to its hosting high numbers of refugees. As urban populations grow—often including many internal migrants—so too does the number of people living in settlements that are not connected to a formal piped water supply. As of 2018, over 1 billion people in the world were reckoned to live in slums, and their general lack of access to affordable and clean water carries serious health consequences on top of the increased immiseration water scarcity causes.
There is compelling evidence that climate change compromises basic services, infrastructure, housing, livelihoods, and health in cities across all regions of the world. But the facts that not all cities are affected equally, and that not all parts of given cities are affected equally, has direct implications for migrants and refugees.
Source: Elliot, K, & Borunda, A. (2020) See which cities will feel the brunt of climate change. National Geographic.
Wealthier and well-managed cities will be better equipped to mitigate and adapt to the impacts of future climate stressors; they are normally situated outside the global South and East—where the majority of migrants and refugees reside. Highly vulnerable regions include sub-Saharan Africa as well as South and Southeast Asia. Developing countries are more likely to disproportionately experience the negative effects of global warming. Such vulnerability is assessed via “the share of the population living in coastal areas below five metres of altitude, the share of agriculture in national GDP, and a country score from the ‘vulnerability index’ compiled by the Notre Dame University Global Adaption Index, [which] measures the degree to which a system is susceptible to, and unable to cope with, adverse effects of climate change.”
Equally, within cities where steep socioeconomic gradients exist between wealthier, better provided-for districts and the urban poor, the less advantaged face unequal access to urban services, facilities, utilities, and protection. Various essays in this Review discuss the inevitable and disproportionate accumulation of migrants and refugees in poorer districts of their “arrival cities”, where they tend to live in informal settlements and work predominantly in the informal economy. Even where social mobility is possible, they initially rub shoulders with existing urban poor and face disproportionately reduced life outcomes in terms of income, housing, safety, education, and health, with findings during the Covid-19 pandemic offering particularly stark evidence of this. The importance of physical location, assets, and capital in mitigating, self-protecting from, and adapting to climate risk in cities is directly relevant to internal and international migrants who are normally disadvantaged in all categories.
Assessing migrant vulnerability
Developing a more precise picture of which communities face particular vulnerabilities in discrete cities is a more granular exercise that is beyond the scope of this overview essay, not least because of the endemic deficiency of specific data and the absence of any standardised approach to gathering relevant data. The reality of millions of irregular and often “invisible” migrants and undocumented urban refugees in a wide variety of cities globally (North and South) compounds the data problem. Insufficient data and a dearth of specifically localised data has been repeatedly highlighted in research as well as in major global declarations and initiatives, including the Sustainable Development Goals (SDGs), UN-Habitat’s New Urban Agenda, and the Global Compact for Migration (GCM). It is a gap that needs to be filled if a better understanding of migrant and refugee climate vulnerabilities in cities is to be achieved.
However, an alternative approach could be to accept that such detailed understanding is not needed if it can be safely assumed that the fate of most urban refugees and migrants will be similar to that of other urban residents who live in informal settlements or low-income and low-infrastructure areas and who have low- paying jobs, often in the informal economy. But such an assumption may be misplaced: the experiences of internal migrants in Guangzhou or Moscow, compared with those in Phnom Penh, Nairobi, Maputo, or São Paulo, will be substantially and materially different. Still, there will be commonalities in terms of the likelihood of internal migrants in all these cities being close to the bottom of the socioeconomic ladder and often living in precarious environments with the fewest assets and resources to protect themselves from impacts of climate change and extreme weather events.
Equally, the conditions and status of international migrants will vary considerably between, for example, those in Gulf State capitals and those in Lagos, London, New York or Bogotá, precluding any blanket statements about their vulnerability to current or future impacts of climate change. The same applies to the experience and quality of life of urban refugees , so it would be hard to meaningfully group refugees living in Berlin, San Francisco or Toronto with those in Jakarta, Cairo or Amman as having the same experiences and risks.
Voting with their feet?
Despite the heterogeneity of experience and vulnerability between refugees and internal and international migrants globally, the fact remains that the vast majority of refugees reside in the global South, and at least 60 percent of those live in cities. Moreover, virtually all urbanisation is currently taking place in the global South, and as millions move from countryside to towns and cities, most will arrive at the ladder’s lowest rungs. South-to-South international migration is more prevalent that South-to-North: “most Africans migrate within Africa, rather than toward Europe or North America: in East, Central, and West Africa, more than 80 percent of international migrants come from a country in the same region.” Lastly, irregular migration is also likely to be more prevalent in the global South. Concerning the number of irregular migrants, there are no reliable figures or even guesses, except for some much-quoted estimates in the US and Europe. But if one considers the common occurrence and frequency of undocumented, foreign-born people living in cities in Central and Latin America, throughout South, Southeast, Central and Far Asia, as well as in Africa and the Middle East, the number is likely to be high. The majority of these are also very likely to be in the lower socioeconomic decile in whatever location they find themselves.
If cities are increasingly vulnerable to the impacts of climate shocks and changes and if cities in the global South are disproportionately vulnerable, then it can be said that most refugees and migrants globally face similar—if not greater—vulnerabilities than cities’ resident urban poor.
When the impacts of flooding, landslides, storms, drought, water scarcity, disease, and high food prices become overwhelming, what options do, or will, urban refugees and migrants have? What happens when cities become intolerable for them?
Those who lack capital or networks or capacity to move will experience forced or involuntary immobility and will have no choice but to struggle, and might depend on government or charitable support for survival. In some cases, such immobile vulnerable groups may constitute humanitarian emergencies. In other cases, they will conceivably join with other immobile and poor groups of city-dwellers to engage in the civil protest, social unrest, or even conflict that some researchers see as the inevitable outcome of intensified climate change.
A recent paper from the National Bureau of Economic Research using a global dataset covering 1970–2000 established that rising temperatures are, in fact, associated with reduced rural-urban migration in poor countries and increased rural-urban migration in middle-income countries. The researchers linked this outcome to “rural-urban earnings differentials and liquidity constraints, which limit the mobility of the poor” The results suggest that the global warming will, “encourage further urbanization in middle-income countries such as Argentina, but could slow urban transition in poor countries like Malawi and Niger”.
Others who have the requisite capital and networks may practice secondary movement—as many of those in mixed migratory flows do already—for a variety of reasons. Environmental factors may come into play here, even if only as “stress multipliers” (enhancing economic drivers, for example) rather than as primary drivers. Such secondary movement can take the form of inter-or intra-city mobility, a return to rural areas, or even travel across national borders. As other essays in this Review highlight, all kinds of mobility are being practiced already, and as urban vulnerability increases due to the intensifying impacts of climate change, they will surely increase in scale, as predicted by the IPCC and others. At the same time, options to move may shrink as regular or irregular, viable and accessible alternatives reduce in number and as mobility becomes more restricted by border controls and other forms of prevention.
Fragmented and politicised response
Despite the high-level exposure, raised awareness and hand-wringing that climate change issues have elicited in the last two decades, the world continues on a dangerous trajectory in terms of carbon emissions and global heating. What were once seen as unacceptable levels of global heating to be avoided at all costs have become the new baseline targets to return to. Meanwhile, while increased international attention has been paid to climate change in relation to cities and the need to improve global management of migration, some states continue to challenge the anthropogenic nature of climate change, and most international efforts focus on the less politically contentious concept of “disaster prevention”.
For example, the UN Office for Disaster Risk Reduction, established in 1999, works towards implementing the Sendai Framework for Disaster Risk Reduction 2015-2030, a roadmap for preventing new and limiting existing disaster risks.
Two newer efforts have worked to link crisis and disaster to mobility. The Nansen Initiative, a state -led consultation process than ran between 2012 and 2015, focussed on “disaster-induced cross-border displacement.” It was the precursor of the ongoing Platform on Disaster Displacement that seeks to implement the recommendations of the Nansen Initiative’s protection agenda. Additionally, the (also state- led) Migrants in Countries in Crisis Initiative was set up in 2014 to improve responses to the needs of migrants in countries (as well as cities) experiencing conflicts or natural disasters.
Organisations such as C40 Cities and 100 Resilient Cities (2013-2019) have linked climate change to cities, while the Mayors Migration Council is the most recent municipal governance network to have a specific focus on migration issues in cities. Alongside these initiatives, high-profile declarations and landmark statements about migrants, migrants in cities, and cities and climate change are found in the New Urban Agenda, the SDGs and the GCM. To date, the issue of migrants and refugees in cities affected by the impacts of climate change has not been a primary focus of research, data collection or commentary.
“Dysfunctional nations, rising cities” 
Although some—perhaps many—cities on the frontline of climate change may be unaware of all these international initiatives, conferences and declarations, the concepts of mitigation, resilience and adaptation that have grown out of the new thinking have in recent years guided policy approaches and international assistance at national and city level. In the absence of other solutions, including cutting carbon emissions—which may already be too little, too late for some climate change processes—cities have been forced to protect themselves where they can from the current and expected impacts of climate change. Evidently, some cities are better resourced and have better planning capacity to do so than others. Many may be too overwhelmed by more everyday management issues to consider protecting residents against future risks, especially those seen as living in their cities temporarily or irregularly, such as refugees and migrants. Beyond the bitter irony that many climate-induced migrants face new climate threats in the cities where they came to seek refuge and new opportunities, it is evident that cities will predominantly have to keep fending for themselves and find their own solutions. Cities will likely face many different iterations of the impacts of climate change with unpredictable repercussions. The urban crises that climate change could cause or contribute to may become a source of destabilisation and civil unrest, with potentially increased discrimination and destitution for the cities’ poorest residents, including those who arrived within mixed migratory flows.
Global “climate injustice” means leaders of towns and cities thousands of miles from the biggest polluters must bear the brunt of the worst impacts of climate change. Thanks to dysfunctional and paralysed global and national systems of mitigation and response, mayors and city managers might once again have to take the lead in effective response and cross-border city-to-city exchanges, cooperation and action.
 Estimated to be around 11-12 million in the US and around 4-6 million in Europe.
 This phrase is borrowed from: Barber, B. (2013) If Mayors Ruled the World: Dysfunctional Nations, Rising Cities. New Haven: Yale University Press.