The United Nations estimates that there are currently about 25 million "climate refugees," people who have had to move from their homeland because of lack of natural resources. The number is greater than both political and religious refugees in the world. Most are in poor, environmentally vulnerable areas, and the number is expected to grow in the next decade by tens of millions.
As developed and developing nations try and work out a climate deal in Copenhagen, award-winning filmmaker Michael Nash will be screening his new documentary film, "Climate Refugees", a project that took him and his film crew around the world for nearly three years documenting the plight of the people who have been forced to migrate, and giving a haunting picture of the future.
They also talked to scientists, aids groups and politicians from both spectrums of the aisle, including Sen John Kerry, D-Mass., and former House Speaker Newt Gingrich, R-Ga. "Climate Refugees" will premiere at next year's Sundance Film Festival.
ABC News asked Nash about the film, the journey and what he hopes people will learn about what he said could be "the greatest challenge mankind's ever going to face."
What is a climate refugee?
A climate refugee is basically someone who is forced to leave their land because they really can no longer survive there, and is forced to move somewhere else.
Climate change, when you really look at it, seems to be really all about water, too much water or too little water. Africa as a continent is a great example of that. There's a lot of parts of Africa that are going through massive droughts right now. They can't grow food. They can't really supply crops for the people who are there. And then you have places like Mozambique, where you have these massive floods. And that's what's happening all over the world that we saw. It's all about water.
What's the basic concept behind your film "Climate Refugees"?
The film really is about the human face of climate change and how the intersection of overpopulation, overconsumption, lack of resources and a changing climate are all colliding now within civilization -- and what's happening is climatic migration. ...
It's interesting because there's a lot of places. ... We travelled around the world for two-and-a-half years documenting the human migration caused by climatic change, and it's a really interesting thing no one's really looking at. People have always kind of migrated, but there's no more available real estate. And now they're crossing borders, which is starting to create conflicts.
In Africa, there are quite a few places that if you trace the root of a conflict, ethnicity may be exploited, but it starts as a fight over resources. Did you find that?
Africa, from a resource-conflict standpoint, really seems to be ground zero -- especially along the [Sahara] desert. The brim of the desert seems to be expanding and challenging people.
But there are other conflicts that are brewing. For example, in Bangladesh [if it] got hit with a large cyclone, or like they did in 1997, or if the sea level rises, you'll have 155 million people, Muslims, who are either going to move into China or India. It doesn't really work.
But initially, from what we saw, the first level of migration will be toward the cities of those countries, but those are countries that are already dealing with a lot of stress to start with. And in time, people are going to start migrating outside of those cities to other places that have resources. People aren't going to cross borders for copper or tin, but they will for water or food.
How much time does the world have before this issue becomes unmanageable?
The number that the experts are throwing out right now is that we currently have 25 million climate refugees. Experts are saying within the next eight to 12 years in Africa, 75 million to 250 million people are basically going to find themselves without water. And they're going to start crossing the Mediterranean looking for places to survive into Europe.
What areas are the most vulnerable?
Really poor countries are going to get hit by this the worst. From a location standpoint, probably the biggest are Africa, parts of Asia, specifically Bangladesh, South America, Australia and the Pacific Islands.
I went to Tuvalu and there are these beautiful little paradises that have sustained life for thousands and thousands of years, and they're starting to go underwater.
Is it only poor nations that will have people migrating because of environmental problems? Are there places in the United States and Europe that are susceptible to this as well?
There certainly are. Alaska, along the eastern and northern brim of Alaska, where all these ... Indian tribes live, they're moving right now. Their villages are falling into the ocean because the shore ice no longer exists during certain seasons. I interviewed one of them and he said, "You know, it's a little scary that within an hour you lose 30 to 50 feet of land."
So it's happening right now in America.
Lester Brown [an author and climate change expert] put it really well in the film, and he said, "Katrina had a million evacuees when the levees broke. Three hundred thousand have not come back." So essentially, he said we have climate refugees within our own country -- 300,000 of them.
What about the argument that it's not only climate change stemming from the actions of industrialized nations, that are causing environmental problems in poorer countries, but also bad commercial and agricultural practices they, themselves, are doing?
Climate change is a threat multiplier, and anything that is kind of bad, [climate change] is only gonna make it worse. If you have in Africa, where people have over-grazed the land, pretty much depleted the nutrients in the land, cut down the trees, that land, in time, becomes desert-like, creating less rain. And you get this runaway effect where it just keeps getting worse.
In China, there's a lot of land where they double-crop the land, where they would grow one crop in the spring ... then they grow another crop four or five months later -- and over time, the soil turns to dust and nothing's left to actually grow anything.
What kind of responsibility do richer nations have to help with this problem? What kind of solutions can there be?
There's going to be collateral damage, but we certainly can stop the majority of this. The numbers that people are throwing around are 150 to 250 million climate refugees by 2050. The Christian Science Monitor has the number up to a billion. That's 20 percent of the population, right now.
The solution is complicated because, first of all, everybody has to be on board that it's man-made -- because if the problem's not man-made, you're not going to get any of these countries who are kind of walking from the blame to pay anything.
A German scientist stated in the film that if you created 25 percent of the damages or put 25 percent of the greenhouse gases in the world like the United States did, you would have to take 25 percent of the world's climate refugees. Now, I don't know how you would get that to work, but what I would say from my own standpoint is that it's a really, really interesting time to be a human being because we're being faced with very, very large decisions right now.
What are some solutions to the climate refugee issue?
Part of the solution is to prevent this problem. There's enough sunlight hitting an Algerian desert in a day to power the world for a year. If you just take America, there's enough wind power in North Dakota, Kansas and Texas to power the United States for a year and that's based on wind turbine technology from 1991. So the solutions are there, it's just the choices we have to make and whether we really want to do them or not.
There are a lot of levees that need to be built up, a lot of sea walls, a lot of things like that. Some people are going to have to move. But we can minimize the damage if we get on with it and stop business as usual.
In the film, Sen. John Kerry says that climate change and migration is a national security issue.
We were surprised when he said that, but as we did more digging we found more people echoing his sentiments. We have an ex-admiral and a three-star general who are saying if we don't go green, in the very near future, in the next decade or two, there are going to be parents in America whose children are going to die on battlefields of wars that never needed to be fought, but are being fought because we didn't go green.