Climate-induced displacement describes the phenomenon whereby individuals and communities are forcibly displaced (within or beyond their nation-state boundaries) by short- and long-term natural disasters that are precipitated or exacerbated by the climate crisis. Such short-term disasters consist of typhoons, hurricanes, wildfires, and tsunamis, while long-term natural disasters include desertification, rising temperatures, and rising sea levels, among others. This section focuses on two of the latter phenomena—sea-level rise and changes to the hydrologic cycle—as well as the added pressures that resettlement itself places on communities and natural resources.

Infographic showing Three drivers of climate forced displacement

Proximate Causes of Climate-Induced Displacement

Sea-Level Rise

Human activities over the past century have caused Earth’s surface temperature to increase, precipitating the melting of glaciers and polar ice caps.32 Due to this ice melt, sea levels worldwide are rising at an annual rate of 0.13 inches (3.2 millimeters) a year, roughly twice the average speed of the past 80 years.33 Further, there is a growing consensus that Earth’s polar ice caps are less stable than previous estimations suggested and that this rate would increase. In its 2013 report, the Intergovernmental Panel on Climate Change estimated that Antarctica melting would contribute just a few centimeters to sea-level rise by 2100.34 Yet it is now believed that continued growth in greenhouse gas emissions over the next several decades could trigger an unstoppable collapse of Antarctica’s ice—raising sea levels by more than a meter by 2100 and more than 15 meters by 2500.35

Sea levels are rising as coastal populations continue to grow. Approximately 38 percent of the world’s population lives in coastal areas, and over the past three decades, coastal populations have increased globally from 1.6 billion to over 2.5 billion.36 The vast majority of these populations are already vulnerable, with over three-quarters (1.9 billion) living in the Global South as of 2007, and with only 15 nations—largely in South Asia, East Asia and the Pacific, and sub-Saharan Africa—containing over 90 percent of the world’s low-elevation coastal zone37 rural poor.38

The risk that sea-level rise poses to such communities is threefold: First, rising sea levels mean that small islands and coastal states must grapple with the possibility of partial or complete submersion. Bangladesh, for example, is projected to lose 17 percent of its total land by 2050, which would displace an estimated 20 million people.39 In addition, the Maldives, at its highest point, is just 8 feet (2.4 meters) above sea level and could lose the entirety of its 1,200 islands as sea levels rise.40

Second, when sea levels rise, even a small increase can have devastating effects on the coastal ecosystems on which such populations depend. Across the globe, people whose livelihoods depend on fisheries are experiencing a decline in revenue and profits as melting polar ice caps harm saltwater ecosystems by increasing the amount of fresh water, which in turn drives saltwater marine life away and harms ocean ecosystems.

The third risk that sea-level rise poses to such communities is the increase in coastal hazards driven by the disappearance of ecosystems. For example, coral reefs protect coastal areas, yet if ocean water temperatures continue to rise, it is projected that by 2050 the ocean will be too warm for coral reefs to survive.41 Salt marshes also protect shorelines from erosion by buffering wave action and trapping sediments, in addition to reducing flooding by slowing and absorbing rainwater, and protecting water quality by filtering runoff and metabolizing excess nutrients. Yet, sea levels are rising and oceans are warming at a rate faster than what many marshes can adapt to on their own. Further accelerating sea-level rise has been associated with saline intrusion, destructive erosion, flooding of wetlands, contamination of aquifers and agricultural soils, and lost habitat for fish, birds, and plants.42 Likewise, barrier islands and sand formations protect coastal areas yet both can be washed away by intense weather events.

Many residents of coastal regions and islands at risk of submersion and other hazards associated with the climate crisis are already migrating to other regions or to nearby countries as their livelihoods become ever more precarious. For instance, between 2005 and 2015, 15 percent (1,500 people) of Tuvalu’s total population had migrated internationally, with many residents having left Tuvalu for New Zealand in search of work under a labor migration program.43

Hydrologic Cycle

The steady rise of global temperatures has directly affected the “hydrologic cycle,” including water vapor concentrations, clouds, precipitation patterns, and stream flow patterns, with such variations possibly affecting the global sea level if the net freshwater content of the ocean is altered. While coastal populations face sea-level rise, inland communities—especially within impoverished countries and countries that derive a relatively large percentage of their GDP from agriculture—are particularly vulnerable to shifts in the weather patterns. This is the case across much of the Global South. In 2010, about 34 percent of the total rural population of developing countries was classified as extremely poor, and about 80 percent of rural households engaged in farm activities that depend on moderate weather patterns.44

For such communities, the risk that a warming climate poses is threefold: Firstly, it would greatly impact weather predictability.45 For example, as the lower atmosphere becomes warmer, evaporation rates will increase, resulting in an increase in the amount of moisture circulating within it. A consequence of higher water vapor concentrations is the increased frequency of intense precipitation events, mainly over land.46 These changes would affect a large majority of the world’s poor who depend on moderate seasonal changes to predict weather patterns and changes in seasons to produce their food.

Secondly, climate-induced changes in the hydrological cycle would affect the availability of water altogether. In parts of the Northern Hemisphere, an earlier arrival of springlike conditions is leading to earlier peaks in snowmelt and resulting river flows. Consequently, seasons with the highest water demand (typically summer and fall) are being impacted by reduced availability of fresh water. Additionally, warmer temperatures have led to increased drying of the land surface in some regions, and increase the incidence and severity of drought. When rain does arrive, much of the water runs off the hard ground into rivers and streams, and the soil remains dry, resulting in more evaporation from the soil and an increased risk of drought. Such impacts of the climate crisis on the hydrological cycle have been clear. For example, the Palmer Drought Severity Index, which is a measure of soil moisture using precipitation measurements and rough estimates of changes in evaporation, has shown that from 1900 to 2002, the Sahel region of Africa has been experiencing far harsher drought conditions.47

Thirdly, climate-induced changes in the hydrological cycle include the phenomenon of desertification, wherein a relatively dry land region becomes arid to the point where bodies of water, vegetation, and wildlife can no longer thrive. Beyond periods of drought, desertification is threatening the livelihood of many communities by completely transforming the ecosystem and diminishing, if not eliminating, the productivity of land. As the land in these regions becomes increasingly arid and uninhabitable, entire communities are being forced to relocate.

Desertification as a driving force of migration has been most notable in communities in East Africa, the Horn of Africa, and the Gobi Desert in China.48 For example, the Gobi Desert in China has been expanding at an accelerated rate at around 100,000 square miles per year since 1950, and as a result, some 24,000 villages in northern and western China have been abandoned entirely over the last half century.49 Likewise, severe droughts and civil strife in Somalia have resulted in what the United Nations High Commissioner for Refugees described as an “exodus” of Somalis to Kenya and Ethiopia in 2010 and 2011, and the shrinking of Lake Chad by 90 percent since the 1960s has put pressure on the 20 to 30 million people that depend on it to abandon agriculture, fishing, and livestock as once-viable sources of income.50

Secondary Outcomes of Climate-Induced Displacement

Joblessness and Resource Competition

The risks associated with the climate crisis fall hardest on nations within the Global South. The risks come from two directions: First, more so than in the Global North, a relatively large percentage of national GDPs in the Global South are derived from rural environments. Second, such nations have less adequate disaster response and management capabilities, and fewer resources to prevent and mitigate the effects of long-term environmental change.135 Thus, climate-induced short- and long-term environmental changes will continue to force many within these nations to migrate internationally. Yet, climate-induced migration across national borders is not always an option, and the push to relocate internally presents its own pressures upon already-strained communities and national economies.135 For example, many climate refugees are rural and coastal residents whose only option has been to relocate internally, oftentimes to urban areas.

These migrants face difficulties familiar to all rural-to-urban migration, including unemployment and poverty, when their rural skills such as herding and farming are far less applicable in urban settings. Further, evidence suggests that internal migration from the climate crisis may itself create more economic and political refugees. The former UN high commissioner for refugees and current UN General Secretary, Antonio Guterres, stated that “climate refugees can exacerbate the competition for resources—water, food, grazing lands—and that competition can trigger conflict.”136 Hence, climate-induced migration can cause population pressures, landlessness, rapid urbanization, and unemployment, which put refugees in danger of resident backlash and worsen existing urban struggles.

Infographic showing numbers of forcibly displaced people worldwide.
  • 32Intergovernmental Panel on Climate Change, “Fifth Assessment Report (AR5).”
  • 33 Robert S. Nerem et al., “Climate-Change–Driven Accelerated Sea-Level Rise Detected in the Altimeter Era,” Proceedings of the National Academy of Sciences 115, No. 9 (2018): 2022–2025.
  • 34 “Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report (AR5)” (Geneva, Switzerland: Intergovernmental Panel on Climate Change, 2013).
  • 35Robert M. DeConto and David Pollard, “Contribution of Antarctica to Past and Future Sea-Level Rise,” Nature 531, No. 7596 (March 2016): 591–97, https://doi. org/10.1038/nature17145.
  • 36 Coastal areas are defined as areas within 100 kilometers of the coast.
  • 37Low-elevation coastal zones are the contiguous area along the coast with less than 10 meters of elevation
  • 38Edward B. Barbier, “Climate Change Impacts on Rural Poverty in Low-Elevation Coastal Zones” (Washington, DC: World Bank, 2015).
  • 39“Bangladesh,” Development Series (Washington, DC: The World Bank, December 2011).
  • 40Richard S. J. Tol, “The Double Trade-off Between Adaptation and Mitigation for Sea Level Rise: An Application of FUND,” Mitigation and Adaptation Strategies for Global Change 12, No. 5 (2007): 741–753.
  • 41J. Tanzer et al., “Living Blue Planet Report: Species, Habitats, and Human Well-Being” (Gland, Switzerland: 69 @haasinstitute World Wildlife Fund, 2015),…. pdf.
  • 42“What Is a Salt Marsh?” National Oceanic and Atmospheric Administration, accessed September 9, 2019,; N. Saintilan et al., “Climate Change Impacts on the Coastal Wetlands of Australia,” Wetlands, (February 23, 2018),
  • 43Oakes et al., “Climate Change and Migration.”
  • 44 Lester R. Brown, “Environmental Refugees: The Rising Tide,” in World on the Edge: How to Prevent Environmental and Economic Collapse (New York, NY: W. W. Norton & Company, 2011).
  • 45 “Nansen Conference on Climate Change and Displacement in the 21st Century” (Oslo, Norway: Norwegian Refugee Council, June 2011), http://www.unhcr. org/protection/environment/4ea969729/nansen-conference-climate-change-displacement-21st-century-oslo-6-7-june.html.
  • 46 “The Water Cycle,” NASA Earth Observatory, (October 1, 2010), features/Water/page3.php
  • 47“The Water Cycle and Climate Change,” NASA Earth Observatory, (October 1, 2010),
  • 48 In 2007, the International Panel on Climate Change projected that East Africa and the Horn of Africa—already struggling with prolonged droughts, desertification, flash floods, and land and agricultural degradation—would be the regions most negatively impacted by the climate crisis. Tamer Afifi et al., “Climate Change, Vulnerability and Human Mobility: Perspectives of Refugees from the East and Horn of Africa” (Copenhagen, Denmark: UN High Commissioner for Refugees, June 2012),….
  • 49 Lester R. Brown, “The Earth Is Shrinking: Advancing Deserts and Rising Seas Squeezing Civilization,” Earth Policy Institute, (November 15, 2006), http://www.; Brown, “Environmental Refugees: The Rising Tide.”
  • 50“One Year On, Somali Exodus Continues Amid Conflict and Poor Rains,” UN High Commissioner for Refugees, (June 5, 2012), briefing/2012/6/4fcddaac9/year-somali-exodus-continues-amid-conflict-poor-rains.html.
  • 135 a b Sybil Lewis, “Keynote: Naomi Klein,” Othering & Belonging, (2015),
  • 136 Melissa Fleming, “Climate Change Could Become the Biggest Driver of Displacement: UNHCR Chief” (Copenhagen, Denmark: UN High Commissioner for Refugees, December 16, 2009), news/latest/2009/12/4b2910239/climate-change-become-biggest-driver-displacement-unhcr-chief.html.