Internal Climate Migration and Managed Retreat in the U.S. by Shannon Bonney

Every day, climate change continues to alter Earth. Its changes affect the entire world, including the United States. Already, it has impacted agriculture and the growing season, increased heat waves and droughts, changed precipitation patterns, and more.[1] Sea level rise in particular presents a significant threat to the United States. I recommend that states develop managed retreat guidelines for coastal communities.

Melting polar ice and global warming drive rising sea levels.[2] Scientists estimate that the global mean sea level will rise by 1-4 feet by 2100.[3] Of course, rising sea level will not be the only hazard. Increasingly strong storms will also make life in coastal areas more difficult, eventually driving people out as repairing and rebuilding becomes too expensive and onerous.[4] In the United States, 39% of the population lives in coastal counties (as of 2010), meaning over 100 million Americans reside in close proximity to these threats.[5] As sea levels continue to rise and floods increase, coastal areas will become less habitable, especially for people who do not have the means to prepare their homes or move to higher ground in their area. As a result, a study predicts that as many as 13 million people may migrate away from coastal areas within the United States by 2100 (based on scenarios of high sea level rise).[6] The International Organization for Migration defines those in this situation as environmental migrants, people who choose or are forced to leave their homes primarily due to environmental changes.[7]

A mass migration – even if not to the level of this upper-end estimation – would severely disrupt the lives of the people involved and the areas they leave. It should also be noted, but is often overlooked, that mass migration could be disruptive to the destinations to which people migrate. For at-risk coastal areas, these impacts include abandoned properties and communities. For desirable, safer migration destinations, it could spell increasing housing prices, which could push out low-income communities.[8]

Proper planning for mass migrations will be essential. Not all states face the same risk, however, and North Carolina, given its populated coastline and sea level rise of up to 11 inches over the past 70 years (which is accelerating quickly), is one state that deserves particular attention.[9] I recommend that the North Carolina state government create guidelines on managed retreat from coastal areas for local governments to follow, should they decide that is the best path forward for their community.

Managed retreat, defined as “the purposeful, coordinated movement of people and assets out of harm’s way,” presents one option for cities most at risk of harm from climate change, particularly from rising sea levels.[10] However, it requires significant planning to be successful. Some pieces of this retreat could include “relocation and buy-back and buy-out programs; regulating types of development allowed; [and] designating no-build areas.”[11] Limiting the growth of these communities will limit the number of properties left behind and the number of people to move, and the government buying private property gives residents the economic freedom to move. Planners also need to identify other areas (particularly in-state, to maintain the tax revenue) that are suitable destinations for these environmental migrants, communities that are away from major environmental hazards and able to accommodate an influx of people.

While managed retreat is seen by some as a last resort, it may become necessary as cities become less habitable. In fact, this tactic is already being used, and “Since 1989, the US Federal Emergency Management Agency (FEMA) has funded managed retreat in over 1,100 counties across 49 states,” although this represents only a small portion of those at risk.[12] Cost remains one of the primary barriers, with relocation estimated to cost between $200,000 and $1m per person.[13] However, with or without managed retreat, people will move away from at-risk areas. Managed retreat allows for a more organized transition and can help mitigate some of the issues that may occur from millions of people relocating on their own.[14] Already, lower-income communities do not possess the same opportunities as wealthier individuals to modify their homes or move.[15] Managed retreat would more readily allow them to remove themselves from a dangerous situation.

A number of cities and states have started taking climate change into account when planning, in hopes of forestalling the need to take more drastic measures.[16] For example, Miami Beach, Florida, facing higher tides, has already begun to prepare by raising streets, building up sea walls, and creating a network of pumps, at a cost of $400m.[17] These methods all help lessen the effects of sea level rise, but the future is uncertain, and these solutions are likely only temporary, as sea levels will continue to rise and storm surges may rise over sea walls. Even with these modifications, rising sea levels will still displace millions of people.

While efforts must be made to slow climate change as much as possible, people simultaneously need to plan for the inevitable effects of the climate change already in motion in order to minimize harm. That planning must include steps by state governments to guide local coastal communities through successfully facilitating a managed retreat.

[1] “The Effects of Climate Change,” Global Climate Change Vital Signs of the Planet (NASA), accessed February 25, 2020,

[2] “The Effects of Climate Change.”

[3] W. V. Sweet et al., “Sea level Rise,” In: Climate Science Special Report: Fourth National Climate Assessment, Volume I (D. J. Wuebbles et al., eds., U.S. Global Change Research Program, Washington, DC, 2017), pp. 333-363, doi:10.7930/J0VM49F2.

[4] Milman, “’We’re Moving to Higher Ground’.”

[5] “What Percentage of the American Population Lives Near the Coast?,” National Ocean Service (NOAA, June 25, 2018),

[6] M. Hauer, “Migration Induced by Sea-level Rise Could Reshape the US Population Landscape,” Nature Climate Change 7, 321–325 (April 17, 2017).

[7] “Environmental Migration,” Environmental Migration Portal, accessed February 26, 2020,

[8] A. R. Siders, “Managed Retreat in the United States,” One Earth 1, no. 2 (October 25, 2019): pp. 216-225,

[9] “North Carolina’s Sea Level Is Rising,” Sea Level Rise (, accessed March 22, 2020,

[10] A. R. Siders, “Managed Retreat in the United States.”

[11] “Coastal Processes, Hazards, and Society | Managed Retreat: Introduction,” InTeGrate: Earth 107: Coastal Processes, Hazards, and Society (The Pennsylvania State University College of Earth and Material Sciences), accessed March 22, 2020,

[12] A. R. Siders, “Managed Retreat in the United States.”

[13] Oliver Milman, “’We’re Moving to Higher Ground’: America’s Era of Climate Mass Migration Is Here,” The Guardian, September 24, 2018,

[14] A. R. Siders, “Managed Retreat in the United States.”

[15] A. R. Siders, “Managed Retreat in the United States.”

[16] “The Effects of Climate Change.”

[17] Oliver Milman, “Atlantic City and Miami Beach: Two Takes on Tackling the Rising Waters,” The Guardian, March 20, 2017,

2 thoughts on “Internal Climate Migration and Managed Retreat in the U.S. by Shannon Bonney

  1. If everyone who reads this only remembers one point, I think it should be this: “with or without managed retreat, people will move away from at-risk areas.” This is such a simple yet compelling argument for the creation of a managed retreat. It seems to leave state governments with an easy choice, as if to say “it could happen the easy way or the hard way.” The logical choice is the easy way. But, as Shannon points out, the easy way isn’t easy by any means, at least not right now. It will take deliberate planning, large-scale action, and a good bit of money to plan for mass migrations, but it will end up saving a lot of trouble in the future. For some policy-makers, it may also be a tough topic to focus on right now – current climate crises and their effects likely take priority. But I think Shannon makes a critical point in emphasizing that, no matter what we do to mitigate the effects of climate change right now, there are guaranteed to be migrations taking place in the future. So if we are committed to the future health of our planet and its people, we must plan now.

  2. Shannon, thanks for the enlightening blog post!

    I found the fact that 100 million Americans live in coastal communities startling. I think it’s easy to think of places vulnerable to sea level rise as sleepy little beach towns, but most major cities in the United States are coastal. When one accounts for that, it becomes clear that this problem is much bigger than people initially think.

    I agree with your proposal that we need to start to planning now for coastal migration. Instead of waiting until there is no choice but to leave, governments need to be proactive. I think governments should also be looking at disaster recovery now as opportunities to build future resilience. For example, should people be allowed to rebuild if a hurricane destroys their house? These are hard questions and I am not sure what legal precedent exists to prevent people from rebuilding if they absolutely want to, but I think this should be a part of the managed retreat plan. Since cities are already allocating large amounts of money to sea level rise prevention (i.e. the $400 million in Miami), perhaps a portion could also be allocated at the city level to the buy-back programs you mentioned. This would also help cities retain their tax base if they expanded city limits inland and moved residents there. I think it’s going to be hard to convince policymakers to do something about a slow growing problem like sea level rise, but I agree with Lindsey that we must start planning now.

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