Coinciding with Earth Day on April 22, the UN agency published data showing how disasters linked to climate change likely worsen poverty, hunger and access to natural resources, stoking instability and violence.
It called on countries to work together to combat climate change and mitigate its impact on hundreds of millions of people.
"From Afghanistan to Central America, droughts, flooding, and other extreme weather events are hitting those least equipped to recover and adapt," it said in a press release on Thursday.
Since 2010, weather emergencies have forced around 21.5 million people a year to move, on average.
UNHCR said that roughly 90 per cent of refugees come from countries that are the most vulnerable and least ready to adapt to the impacts of climate change.
These countries also host around 70 per cent of people internally displaced by conflict or violence.
Citing the case of Afghanistan, UNHCR noted that it is one of the most disaster-prone countries in the world, as nearly all of its 34 provinces have been hit by at least one disaster in the past 30 years.
The country is also ranked the least peaceful globally, owing to longstanding conflict that has killed and injured thousands of people and displaced millions.