By 2050, 86-million "climate migrants" will be displaced in Sub-Saharan Africa, 40-million in South Asia and 17-million in Latin America - 143-million in all - according to the report, which the bank said was the first to address the question of migration spurred by climate change.
These regions are home to more than half the developing world's population, with 2.8% of inhabitants among those at risk, the report said.
So far climate change has inexorably become an "engine of migration", forcing individuals, families and even whole communities to seek more viable homes, World Bank CEO Kristalina Georgieva said in prepared remarks presenting the report.
"Every day, climate change becomes a more urgent economic, social and existential threat to countries and their people," she said.
"The number of climate migrants could be reduced by tens of millions as a result of global action to reduce greenhouse gas emissions and with far-sighted development planning."
By that year in Bangladesh, climate migrants could be the single-largest group among all internally displaced persons.
And in Mexico, people will increasingly gravitate towards urban areas from regions vulnerable to climate change.
At a recent conference of the International Organization for Migration, France's minister for ecology and solidary transition Nicolas Hulot said the climate was already displacing twice as many people as conflicts were, and that it might already be the main cause of migration.
Gilbert Houngbo, president of the UN's International Fund for Agricultural Development, said fast-growing rural populations in Sub-Saharan Africa that cannot grow enough food to feed themselves were particularly vulnerable.
The region's inhabitants currently number 645-million but will add another 1.4-billion by 2055, according to the UN Food and Agriculture Organization.
Nevertheless climate-linked migration need not descend into humanitarian crisis, according to the World Bank.
Researchers believe the number could be reduced by 80% if countries reduce emissions, account for migration in development planning and make investments in studying the process of internal climate migration.
They developed three scenarios: a worst case, involving high greenhouse gas emissions, a scenario in which better environmental policies are enacted and one with greater development.
"Without the right planning and support, people migrating from rural areas into cities could be facing new and even more dangerous risks," Kanta Kumari Rigaud, a chief author of the report, said in a statement.
"While internal climate migration is becoming a reality, it won't be a crisis if we plan for it now."
Source: AFP
