While the causes might not be the same across the world; conflict, climate change, poverty, migration, natural disaster, war and economic downturn are some of the major cause of the problem. While the causes might not be the same across the world; conflict, climate change, poverty, migration, natural disaster, war and economic downturn are some of the major cause of the problem. While the causes might not be the same across the world; conflict, climate change, poverty, migration, natural disaster, war and economic downturn are some of the major cause of the problem.