Making the most of human mobility, by António Guterres, United Nations High Commissioner for Refugees, and William Lacy Swing, Director General, International Organization for Migration

Human mobility ranks alongside population growth, urbanization, climate change and resource scarcity as one of humankind's megatrends. It is also, and always has been, one of the ways that people in difficulty seek to improve their lives.

International migration - which already stands at well over 200 million people - is likely to increase substantially over the coming years. Throughout the globe, people are being pushed and pulled by events and forces that are largely beyond their control.

Natural disasters, for example, are growing in frequency and intensity. Meanwhile, the nature of conflict is changing. Civilians are increasingly being targeted for attack, often by unruly armed groups and militia forces whose primary objective is to displace people and seize their possessions and land.

An instinctive reaction to migration, particularly when economic times are lean, is to try to block or end it. Rich states formulate policies to make arrival harder while the unscrupulous use anti-foreigner sentiment to stir discontent or win votes. In developing countries, which host four-fifths of the world's refugees and migrants, sympathy gives way to fatigue and resentment against refugees and migrants grows.

For IOM and UNHCR, the organizations we lead, both of which are approaching their 60th anniversaries, the interaction of the megatrends and the evolving nature of conflict and displacement is blurring the traditional distinctions between refugees and migrants and accentuating the importance of our working together in response.

Migrants and refugees are using the same routes and means of transportation to reach the same destinations. Largely because of tighter border controls, people on the move often find themselves in the exploitative hands of human smugglers and traffickers, entering countries without passports or visas and often placing a heavy burden on asylum determination and immigration procedures.

According to international law, everyone is entitled to exercise their fundamental human rights. Refugees, asylum seekers and irregular migrants are no exception to that rule. In reality, however, the rights of migrants and refugees are often violated.

In places throughout the world, they are subjected to arbitrary and discriminatory treatment by the authorities and other members of society. In some of the world's most prosperous states, women and children who have arrived in a country without the required papers can be held in detention for weeks or months on end.

Even the most fundamental human rights principle - that people should not be returned to a country where their life or liberty is at risk - is being tested. A recent rash of involuntary returns in regions across the globe testifies to the vulnerability of even long-established legal norms.

States have every right to control their borders and to safeguard the security of their nationals. But they also have a responsibility to craft constructive responses to the challenges posed by the growing mobility of the world's population.

On one hand, there is a need to ensure that people can move by choice rather than by necessity, and that they have safe, orderly and lawful migratory channels available to them. When this is achieved, the contribution that migrants and refugees make to the global development process is maximized.

On the other hand, it is essential for states to ensure that victims of persecution are effectively protected when they flee their countries. Millions of people throughout the world owe their lives to the fact that they were able to become refugees.

Meeting these twin challenges is key. We must not allow political opportunism and xenophobic sentiments to prevent people like Albert Einstein and Marlene Dietrich from finding the sanctuary they need. We must not allow the rich contributions of refugees and migrants to be obscured.

In a globalized, interconnected and insecure world, people will become increasingly mobile. Our response should not be governed by fear and rejection. Instead, a determined effort is required to protect the interests and rights of all.