When home becomes uninhabitable—whether due to conflict, climate change, or other external pressures—people are faced with little choice other than to embrace displacement. This can be over borders and across continents. Human mobility and migration have long been drivers of development and innovation.
But in a world characterized by multiple crises—economic, conflicts, and disasters—the magnitude and character of these crises have changed over time and are amongst the most important phenomena this century.
The effects of climate and environmental changes are increasingly forcing displacement as people are forced to move from their homes. According to the World Bank, water scarcity is linked with a 10 percent rise in global migration, and forcibly displaced persons and their host communities face numerous water-related risks.
While the number of internally displaced persons remains a relatively small proportion of the global population (71.4 million), the numbers have risen by 340 percent in two decades according to the Internal Displacement Monitoring Centre. This not only poses significant humanitarian challenges but also contributes to and is worsened by environmental and climate impacts, further exacerbating the complexities of forced migration.
The persistence of the trend of extreme temperatures and climate-related events disasters has triggered an unprecedented surge in large-scale, prolonged, and repeated displacements worldwide in the last two years in many parts of the world in Pakistan, the Philippines, Somalia, China, India, Bangladesh, Brazil, Colombia, and Kenya.
The environmental considerations and implications are many from the provision of land, infrastructure, services, and resources to dealing with unintended environmental impacts such as wastes and pollution from rapid forced migration placing impacts on nature and other natural resources.
In many locations, and specifically in small island nations, habitability is expected to decrease. This is anticipated due to rising temperatures, rising sea levels, and degradation of buffering ecosystems, which in turn exacerbate human exposure to ocean hazards.
The IPCC Sixth Assessment Report noted that those relying on coral reef systems for livelihoods may exceed adaptation limits well before 2100 even for a low greenhouse gas emission pathway. Those low-lying and coastal areas are at particular risk hence the ability of these areas to support human life and livelihoods. Extreme heat also threatens the habitation of communities in urban areas in the tropics and arid and semi-arid regions of the world.
In a recent modeling study, scientists projected that over the coming 50 years, up to three billion people could be living well outside climate conditions (and particularly temperature) that have served humanity over the past 6,000 years, and worse, that by 2070, absent climate mitigation or migration, certain regions—Northern South America, central Africa, India, and northern Australia—could simply become too hot to allow human life.
While the temperate regions of the world are unlikely to become uninhabitable due to temperatures alone, extreme conditions such as flooding, wildfires, and intolerable low air quality, could eventually render some densely populated urban areas as well as rural communities—like those exposed to wildfires in the wildland-urban interface—as prohibitively dangerous locales, where seasonal displacement (temporary inhabitability) becomes the norm.
A recent study showed the number of extreme fires has risen more than 10-fold in the past 20 years in temperate conifer forests, and nearly seven-fold in the boreal forests of northern Europe and Canada as a result of climate change.
As places become uninhabitable, migration coupled with displacement is anticipated and the need for social services will increase. Semi-arid areas, the tropics, and some low-lying deltas and islands require prioritization for climate justice. Solutions need to be generated and investments made to address habitability risks focusing on areas to implement adaptation.
