"Estimates of the number of people who will be compelled to move by 2050 because of climate change range from 25 million to 1 billion. The most widely cited figure appears to be 200 million climate migrants by 2050. It has been estimated that between 500 million and 600 million people (approximately 10% of the world's population) are at extreme risk due to climate change" (1).
"Experts estimate that most people who are uprooted by climate change will remain in their own countries, but a minority will need to relocate abroad. Considering the sheer number of climate migrants expected in the coming years, even a small fraction seeking to resettle in Canada could constitute a large number relative to Canada's current intake of new residents" (2).
"It is impossible to predict with any degree of certainty how many additional people each year will need resettlement due to the effects of climate change. However, it seems certain that climate change will be the source of additional pressure on Canada's humanitarian immigration program to expand, perhaps substantially, in the coming decades" (4).
Becklumb, Penny. Climate Change and Forced Migration: Canada's Role. Library of Parliament, 2013. Background Paper 2010‑04‑E.
"Anthropogenic sea-level rise (SLR) is predicted to impact, and, in many cases, displace, a large proportion of the population via inundation and heightened SLR-related hazards. With the global coastal population projected to surpass one billion people this century, SLR might be among the most costly and permanent future consequences of climate change."
Hauer, Mathew E., et al. "Sea-Level Rise and Human Migration." Nature Reviews Earth & Environment, vol. 1, Jan. 2020, pp. 28-39.
"[T]he UN Human Rights Committee has stated that countries may not deport individuals who face climate change-induced conditions that violate the right to life. . . . The Committee also clarified that individuals seeking asylum status are not required to prove that they would face imminent harm if returned to their countries. The Committee reasoned that climate change-induced harm can occur both through sudden-onset events (such as intense storms and flooding), and slow-onset processes (such as sea level rise, salinization and land degradation). Both sudden-onset events and slow-onset processes can prompt individuals to cross borders to seek protection from climate change-related harm."
Historic UN Human Rights Case Opens Door to Climate Change Asylum Claims. United Nations. Office of the High Commissioner for Human Rights, 21 Jan. 2020.
"We show that for thousands of years, humans have concentrated in a surprisingly narrow subset of Earth’s available climates, characterized by mean annual temperatures around ∼13 °C. This distribution likely reflects a human temperature niche related to fundamental constraints. We demonstrate that depending on scenarios of population growth and warming, over the coming 50 y, 1 to 3 billion people are projected to be left outside the climate conditions that have served humanity well over the past 6,000 y. Absent climate mitigation or migration, a substantial part of humanity will be exposed to mean annual temperatures warmer than nearly anywhere today."
Xu, Chi, et al. “Future of the Human Climate Niche.” Proceedings of the National Academy of Sciences of the United States of America, vol. 117, no. 21, 26 May 2020, pp. 11350-55.