A man delivers his goods through a flooded street in Mumbai, India. Photo: Hussain_Quantum (flickr)

It should be no surprise that armed conflicts force millions of people from their homes each year. In fact, 4.6 million people were displaced by conflict and war in 2008. But I was shocked to learn that the number of people displaced by climate change is four-times greater than those displaced by conflict. That's about 20 million people — roughly the population of Australia — that have been forced to relocate because of natural disasters like flooding, earthquakes and storms.

This figure comes from a joint study by the United Nations Office for the Coordination of Humanitarian Affairs and the Internal Displacement Monitoring Centre and is the first large-scale look at how climate change is effecting human populations. It provides data on exactly how carbon emissions have affected human lives, and it offers a somewhat harsh glimpse into what will happen if the situation is left unchecked.

Photo: Geoff Oliver Bugbee for Mercy Corps

A few months ago, I wrote about a team of journalists reporting on water issues and conflict in Kenya and Ethiopia, where a tremendous drought is spreading across the region. Pastoralists — herders whose livelihoods depend on the animals they breed and tend — are running out of water and pasture land. As a result, they are crossing borders and traditional tribal boundaries in pursuit of water. This search for scarce resources is leading to tensions, as The East African Standard reports from Nairobi:

"There is already a build-up of inter and intra clan tensions over water and pasture," says the DO [District Officer]. In fact, he says, they have had to quell inter clan clashes at Sake, with the assistance of elders. Those far away from the Ethiopian border have been left at the mercy of nature, the Government and development agencies, to provide water.

In Ethiopia, the reporting team created a film that compellingly illustrates the oncoming crisis. “Pastoralists are more vulnerable to drought than they were 40 years ago," the film tells us. "Researchers predict that they will be some of the first people on Earth forced to abandon their way of life due to climate change.”