The Intergovernmental Panel on Climate Change (IPCC) report issued in February 2022 paints a dire future for the human race. Recorded global temperatures have already risen by 1.1 degrees Celsius (2 degrees Fahrenheit) since the Industrial Revolution. At the Paris Climate Summit in 2015, world leaders have vowed to limit warming to no more than 1.5 degree Celsius compared to preindustrial level. That is a mere 0.4 degree away. Achieving that goal would require nations to achieve carbon neutrality by 2050 or sooner—a goal that most nations are far off track. Continuing business as usual would mean a warming of at least an additional 1 to 2 degree Celsius by the end of this century. The report warns that if average global warming passes 1.5 degrees C, even humanity’s best efforts to adapt could falter.
With the current level of warming, we have already experienced exacerbating floods, coastal storms, droughts, and wildfires. In all, 3.3 billion to 3.6 billion people—nearly half of humankind—are “highly vulnerable” to climate change today, the report says. Further warming will possibly bring about desertification, widespread thawing of permafrost, drop in agricultural productivity, and collapse of some ecosystems such as coral reefs, wetlands, and rainforests.
In 2019, the New York Times and ProPublica collaborated to report that 1% of the world is a barely livable hot zone. With a moderate carbon emission trend, by 2070, that portion could go up to 19% (figures below). This level of warming and its impacts such as droughts and extreme weather will likely trigger massive migration of people from these areas to more livable ones. Migration is driven not only by extreme heat alone, but also by violence, natural disasters, water shortage, and poverty. A warming climate could cause all of these consequences.
The World Bank Groundswell report (2018) focuses on climate migration in three regions—Sub-Saharan Africa, South Asia, and Latin America. Together, they represent 55% of the developing world’s population. The report estimates that more than 200 million people could migrate due to climate change by 2050, with most movement occurring within countries (two figures below). They will migrate from less viable areas with low water availability and crop productivity and from areas affected by rising sea level and storm surges. The poorest and most climate-vulnerable areas will be hardest hit.
People are already beginning to flee. Of the three regions studied in the Groundswell report, Latin American is closest to home. Many US politicians are already up in arms about refugees from Central America. Many refugees from this region are driven away by violence, corruption, lack of opportunity, and poverty. All of these factors can be linked directly or indirectly to climate, even though climate is not the only root cause. People in this region rely on agriculture for food and livelihoods, while the region is highly susceptible to hurricanes and droughts. For example, considerable displacement was caused by the 2020 hurricane season. Guatemala, Honduras, and Nicaragua in particular were seriously impacted by Hurricanes Eta and Iota in November 2020.
El Salvador, Guatemala, and Honduras all face increasing food insecurity. Diminishing livelihood and development resources breed violence and corruption. Contrary to what the Groundswell report argues, gang violence makes internal migration untenable in El Salvador, Guatemala, and Honduras. Negative impacts from climate and violence reinforce each other, increasing external migration. The result is hundreds of thousands of refugees from these three countries have trekked through Mexico and gathered along the US southern border.
For all the reasons for which people migrate, one trend is clear, they gravitate toward cities, where migrants stretch infrastructure, resources, and services to their limits, pushing people further into poverty. People will congregate in slums, with little water or electricity, where they are more vulnerable to flooding or other disasters. The slums fuel chaos, violence, and political instability. For example, the World Bank Groundswell report estimates that East African cities like Addis Ababa, in Ethiopia, the population has doubled since 2000 and is expected to nearly double again by 2035. In Mexico, the World Bank estimates, as many as 1.7 million people may migrate away from the hottest and driest regions, many of them winding up in Mexico City.
Migration will not be limited to the developing world. The article Future of the Human Climate Niche (2020), published in the Proceedings of the National Academy of Sciences, mapped the regions where temperature and precipitation have been most suitable for human habitation. In the US, that region today stretches from the Atlantic seaboard through northern Texas and Nebraska, and the California coast (upper figure below). As the climate warms, the region could shift northward. Under a moderate carbon emissions trend, by 2070, much of the Southeast becomes less suitable (lower figure below).
In 2018, the Journal of the Association of Environmental and Resource Economists published the article Climate Change, Migration, and Regional Economic Impacts in the US. This article suggests that 1 in 12 Americans in the Southern half of the country will move toward California, the Mountain West or the Northwest over the next 45 years because of climate influences alone.
Compared to the three regions studied in the World Bank Groundswell report, Americans are much richer, and thus more insulated from the shocks of climate change. Americans have been conditioned not to respond to geographical climate threats as people in the rest of the world do. But even in the US, the migration process has already begun. For example, hundreds of thousands of people who fled New Orleans during Hurricane Katrina in 2005 and from Puerto Rico during Hurricane Maria in 2017 have never returned.
ProPublica concluded that “Policymakers, having left America unprepared for what’s next [in climate change], now face brutal choices about which communities to save—often at exorbitant costs—and which to sacrifice. Their decisions will almost inevitably make the nation more divided, with those worst off relegated to a nightmare future in which they are left to fend for themselves.”