War. Persecution. Oppression. People flee their countries and become refugees for many reasons. And not too far in the future, more and more could flee something else — the effects of a changing climate.
Already, sudden-onset disasters like floods, storms and wildfires displace an average of 21.5 million people every year worldwide. On the other hand, low-onset disasters like rising sea levels, increasing temperatures and land and forest degradation increase would force even more people to move.
For example, more than 500 million live in the Middle East and North Africa. One of the all-time highs in the region hit 129 degrees in 2016. By the end of the century, midday temperatures during hot days could regularly hit close to that, at 122 degrees.
The number of those hot days has already doubled since 1970, and during this century, they're expected to only increase. Instead of about 16 each year, by 2050, there could be 80 annually.
It won't just be the Middle East. If greenhouse gas emissions aren't scaled back, almost 75 percent of the world's population will be exposed to potentially lethal heat waves by 2100.
In the Caribbean, hurricanes are already forcing people to move. For the first time in 300 years, everyone left the island of Barbuda after Hurricane Irma. Hurricane Maria similarly devastated the island nation of Dominica.
Not long after the storm, Dominica's prime minister told the U.N.: "To deny climate change is to procrastinate while the earth sinks; it is to deny a truth we have just lived. It is to mock thousands of my compatriots who in a few hours without a roof over their heads will watch the night descend on Dominica in fear of sudden mudslides."
Right now, there's no internationally accepted definition for those displaced by the climate. You'll hear the term "climate refugees," but the United Nations hasn't endorsed it. The International Organization for Migration uses "environmental migrants."
As the effects of climate change worsen, we might not only need a definition — but also a solution.