The Greatest Migration: As Rainfall Changes, Humans Pack Their Bags

The floods that swept Thailand in 2011 may have been the most dramatic demonstration of how changing rainfall affects human lives, but they’re far from the only example. Photo courtesy of the U.S. Navy.

Decades from now, historians may look back on 2012 as the year that the climate change chickens came home to roost. Each season brought a fresh meteorological anomaly: a weirdly warm winter was followed by a brutally hot, dry summer, which gave way to an autumn marked by one of the most destructive storms in American history, made worse by years of sea level rise. But while climate-fueled disasters like superstorms and crop failures are a relatively recent development in the United States, such fiascos already threaten life and property on a daily basis in less well-off nations. Bangladesh, for example, faces an escalating barrage of cyclones, sea level rise, and drought that annually kills thousands and cripples the country’s prospects for growth. As developing countries experience increasingly severe climate impacts, their citizens may abandon their homes, both by choice and by necessity, to escape rising oceans, extreme weather, and droughts and floods.

Few researchers have spent as much time pondering the future of climate-driven human movement as Koko Warner, a social scientist at United Nations University. In late November, Dr. Warner and her team released their latest research, a report called “Where the Rain Falls” that draws upon interviews with hundreds of families across eight countries to detail how shifting rainfall patterns may be driving migration in the developing world. As precipitation becomes less predictable, the report implies, society’s poorest and most vulnerable members will face a disproportionate share of the risk. Sage Magazine recently caught up with Warner to discuss changing rainfall patterns, the future of human movement, and why every migrant wants to settle near the church.

Sage Magazine: I think many people are under the impression — I certainly was before I read your work — that by this point in human history, the age of human nomadism is over. But Where the Rain Falls reveal that migrations are happening all over the world, all the time, in response to environmental impacts.

Koko Warner: Right. We looked at a climatic stressor — changes in rainfall variability — in eight different countries: Guatemala, Peru, India, Bangladesh, Ghana, Tanzania, Vietnam, and Thailand. We wanted to find out what changes in rainfall patterns mean for food security and household economies, and how migration behavior changes, or doesn’t change, when households face rainfall stressors. We were primarily talking to small-holder farmers growing food for consumption and for their household economy. And in all of the countries, to one degree or another, we found that the most vulnerable households make migration decisions based on perceived rainfall variability and food security.

Photo courtesy of United Nations University.

Sage: So just to be clear, you correlated migration patterns with people’s perceptions of rainfall rather than measured rainfall.

Warner: Exactly. We did household surveys and conducted group discussions and interviews with community members to gauge their perceptions. We then worked with the national and local meteorology offices to see if these perceptions of variability matched up with meteorology data, and in almost all cases they did.

Sage: “Changes in rainfall variability” could mean lots of different things. Do you find that floods or droughts are more powerful drivers of migration?

Warner: I’d say equally. Households consistently told us they’re experiencing changes not only in the timing of rainfall — it’s too early, it’s too late, there’s too much, there’s too little — but also in the quality of rainfall. The quality of rainfall is the hardest to measure with meteorology data: gauges often just give you a 24-hour reading, so it’s hard to know how many centimeters you got in a given hour. But people were telling us the intensity of rainfall was indeed changing, which has major implications for erosion and whether or not seeds get washed away.

Sage: In the report, you describe how some households were more resilient to rainfall variability and migration than others. What types of households fared the best?

Warner: The resilient households often send younger people — 20-somethings who have better education than their parents, who migrate at any old time rather than being as dependent on climate or seasons, and who also send back remittances to their families. We found that migration pattern most strongly in Thailand, where a lot of rural households have members who are actually migrating internationally.

By contrast, people from vulnerable households are not migrating very far, rarely across national borders. They just don’t have the means to get that far. Their migration patterns were often from one rural area to another, and depended largely on their own skill-sets. If they have mostly agricultural skills, they’ll have a hard time diversifying their livelihoods, and in the hungry season they’ll have to move to other agricultural areas in search of jobs.

Sage: I’m sure it varies a lot from case to case, but when vulnerable people are forced to migrate between rural areas, how far are they going? Are they just heading over to the village next door, or are they forced to move hundreds of miles?

Warner: The distances that people migrate have a lot to do with their options. Are they close to a highway? Do they have enough money for bus fare? In Ghana, people’s ability to pay bus fare affected how far they got. In Tanzania, we sampled in the area of Mount Kilimanjaro, and we saw a lot of elevation differentiation in mobility patterns — it almost seemed like those communities were commuting between elevations, moving relatively short distances over shorter periods of time, although the link with rainfall variability was still there. In Bangladesh, people were moving to different sub-regions of the country in search of areas with less soil degradation and better agricultural conditions.

Sage: What do migrants do when they arrive at the end of their journeys? Do they stay with relatives? Do they set up camps? How do they adjust to their new homes?

Warner: That’s a great question, but unfortunately I don’t know the answer. This phase of our research was focused on areas of origin — where these people are coming from. And our research shows that migration isn’t just about the people leaving; it’s about the people who stay behind. If the migrants who go out looking for sacks of food or money to send back to their families are successful, it makes all the difference in the world for the people left behind.

Migration also has differentiated impacts. In Ghana, Tanzania, and Bangladesh, we typically saw women taking on double and triple burdens: having to do the agricultural work, keep up the household economy, and care for children and elderly parents. We’re looking at migration as a system, not just at the people who leave.

Sage: How can you tell when a household is vulnerable versus when it’s resilient?

Warner: The resilient households were telling us that they were not only engaging in agriculture, but had three or four different livelihood options. Resilient households also had better access to social support groups, along with formal and informal institutions of social resilience.

Sage: I like that phrase — “institutions of social resilience.” What’s an example of such an institution?

Warner: A friend of mine, Robin Bronen, is working on community relocation in Kivalina, Alaska [currently undergoing a planned relocation to escape sea level rise]. When you relocate, you change the spatial distribution of the town, and in Kivalina everybody wants to live close to the bar, the church, and the school. Because that’s where social interaction happens — that’s where the power is.

That’s also where we see resilient households in our rainfalls research — closest to the bar, the school, and the church. Households who had less access to those institutions were less socially included and often were not favored politically. While politics weren’t part of our research, they do hold implications for how we conduct climate adaptation and how we channel support for people.

Sage: One of the things that makes Kivalina so interesting is that, while they’re already losing some land, their relocation is also proactive — they see that their village is in deep trouble long-term. By comparison, it seems that the migrations you’re describing are reactive: the rain falls, or the drought comes, and the people move after the fact. Did you see any communities that anticipated climatic stressors and migrated before they struck? 

Warner: Not yet. People want to remain where they are, and they’re doing as much as they can to stay. But the farther they get down the road of vulnerability, the more erosive their coping strategies become.

Sage: What do you mean by erosive coping strategies? Are you referring to literal erosion, like people planting on more marginal land?

Warner: We see all kinds of impacts. The stories of older people are wonderful resources for social science — their memories and observations are just gems. We heard older people in the Sahel belt saying that, before the great drought of the late 1970’s and early 80’s, they had forests, and depended on hunting and forestry for their livelihoods. But when the droughts came, they had to cut down all the trees to sell the wood and survive, and now they can barely make ends meet.

That’s when you see the erosive coping strategies: when surviving becomes more important than thriving. You start seeing tradeoffs, people — especially women — saying, ‘Okay, I’ll eat less in order to stay here, or I’ll make sure that the children have enough, or I’ll eat less and make sure that my husband has enough out in the fields. We’ll start skimping on school tuition and just send our kids sporadically to school.’ And it just goes down this road.

Sage: You mentioned earlier that most of the migrations that you witnessed were within a home nation. But as the impacts get bigger and certain places grow less habitable, as you say, can you imagine societies moving en masse from country to country?

Warner: The big question in the room, the holy grail of this research, is to understand what’s going to happen in the future. If our climate changes as significantly as it could, the issue will be population redistribution, not just migration. Seventy percent of the world’s megacities are within two kilometers of the coast, and they’re often in low-elevation areas. And in the resilient households in our rainfalls research, a lot of young people moved to cities, where they have greater livelihood diversification options.

So you could start seeing greater concentrations of people living in social nodes that may offer good opportunities short-term, but are physically located in vulnerable locations, where they’re exposed to other climatic stressors like sea level rise or cyclones.

Sage: If you were a policymaker rather than a researcher, how would you apply the findings of your report? Would you use it to help vulnerable communities migrate in a way that’s less disruptive to them? 

Warner: Here’s the ironic thing: our research has told us a lot more about efforts to build livelihood resilience than about migration policy. People will migrate, and while I know there’s a big debate about national borders, it’s very hard to stop people from moving. We want to make sure that people are moving under desirable circumstances, where they have options and are informed of them. We also shouldn’t underestimate the powerful force for good that migrants are in the communities they go to.

Sage: Really? Migrants are a force for good? You hear so much about how climate refugees are going to create conflict. 

Warner: The diaspora has a lot of knowledge, and that’s an area of unexplored potential. Migrants are capable of bringing in education, encouraging integration, building community, introducing new skill-sets. And yes, there can also be conflict and tension; we’ve found that in our research as well. But there’s as much potential for enhanced cooperation as there is for tension.

Sage: How do you think the migration conversation is going to play out long-term? Are you confident that societies will figure out a way to successfully navigate large-scale movements?

We have a colleague named Bob Ford, a GIS specialist at the University of Rwanda, and he’d reviewed one of our previous reports, “In Search of Shelter.” As we were talking to him during the review, he said something I’ll never forget. Here in Africa, he said, relatively small, marginal shifts in climate send masses of people from rural areas to the cities, just in search of a place to survive. He said the fact that we see this much ferment now, before climate change has really unfurled itself, indicates that we have to get prepared.

And that has stuck with me as a motivation. I’m not a historian, but we forget that after the height of the Roman Empire there was a Dark Age that lasted for hundreds of years. Human society can regress.

Benjamin Goldfarb

Ben Goldfarb is a freelance writer whose work has appeared in The Guardian, OnEarth Magazine, Earth Island Journal, and elsewhere. He is a former Editor-in-Chief of SAGE Magazine. Check out his writing at and hit him up at @bengoldfarb13.

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