By Antonio Guterres, U.N. High Commissioner for Refugees

Today, on World Refugee Day, I am joining southern Sudanese refugees as they return home from Uganda to begin rebuilding their lives after decades of conflict. Although largely unreported, with help from the UN, refugees are starting to return to southern Sudan from refugee camps in Uganda, the Democratic Republic of the Congo, Kenya, Ethiopia, and the Central African Republic. Others are returning from exile in Libya and Egypt, as well as from other parts of Sudan itself. The repatriation of these refugees is a ray of hope here in the epicenter of one of the world's great displacements, but, clearly, so much more needs to be done. Over the last few days in Sudan, I have seen firsthand the stark reality of forced displacement as well as some of its possible solutions.

The massive displacement in Darfur represents only a portion of the almost 40 million people worldwide who have been uprooted and forced to flee violence and persecution, and in the future we are likely to see even more people on the move. Many of them will be searching for economic opportunity and better lives or escaping environmental degradation and natural disasters. Others will be forced to flee failing states wracked by violence and persecution. But in most instances, people are fleeing a combination of these factors, compounding one another to provoke a perfect storm of loss and dislocation.

Hopes that globalization would naturally bring steady growth while also narrowing the gap between rich and poor have not been fulfilled. While global trade and wealth have indeed increased, the gap between the world's rich and poor is widening, driving more people to move and to fall prey to unscrupulous groups who engage in human smuggling and trafficking--a business worth billions of dollars a year.

Climate change and environmental damage lie behind increasingly frequent natural disasters with dramatic human consequences. Different models of the impact of climate change all present a worrying picture of human displacement. East Africa offers a stark example. All predictions are that desertification will expand steadily, making it difficult for people to earn a living and provoking further migration. All of this is happening in the absence of international capacity and determination to respond.

People are also fleeing war and persecution. Even when we have plenty of early warning, the international community has repeatedly failed to prevent conflicts. Instead, agencies like mine are left to deal with the human consequences. Prevention is possible, more effective, and cheaper. But it requires wisdom, political and diplomatic effort, and an investment in eliminating the root causes, including the social and economic ones.

Sudan's Darfur crisis is a good example of the complexities. The conflict has political roots, but is also fueled by increasing competition between traditional herders and farmers for scarce resources, especially water. When this is linked with political tensions, the results are explosive.

It is time to recognize that we are facing what is nothing less than a new paradigm of displacement in the 21st Century, with a plethora of push factors driving people from their homes on an unprecedented scale. There are no easy answers, but, while the international community grapples with the root causes of displacement, it must pay more attention to protecting the vulnerable and building opportunities for their futures.