LONDON (AlertNet) - Imagine fleeing your country and having to walk for several days before being able to sneak across the border into a foreign country that views outsiders with hostility.

Now imagine you are seven years old and making the trip alone with no food or water and just the clothes on your back.

Hundreds if not thousands of Zimbabwean minors have done just that in recent years - driven from their homes by chronic food shortages and an economy brought to the brink of collapse by recession and hyper-inflation.

Many have ended up in neighbouring South Africa, where they often face poverty, harassment and xenophobic attacks. But because most are not refugees as defined by a 1951 Convention that applies only to people who have fled violence and persecution, they receive limited legal protection.

There has long been an argument to expand the definition of a refugee to take into account the changing face of forced migration in the decades since the convention was drawn up.

Advocates of reform say warnings that climate change will force up to 250 million people from their homes by 2050 mean a rethink is needed more than ever.

However, critics say widening the "refugee" category would erode asylum seekers' rights and face opposition from states reluctant to sign up to new laws obliging them to provide protection for more people.

In a recently published paper, two academics from Oxford University have come up with a new term, "survival migrant", to accommodate groups who do not fall within the legal refugee definition.

They say "survival migration" refers to those fleeing "an existential threat to which they have no domestic recourse" due to a combination of state collapse, livelihood failure and environmental disaster.

"What constitutes existential threat? It's not just about the threat to life but the rights without which it is impossible to enjoy other rights, namely basic subsistence, basic liberty, basic security," said Alexander Betts, who co-wrote the paper.

"The existing refugee definition, in only looking at persecution, speaks to the narrowest element of security but doesn't speak to the other two," Betts told AlertNet. "Recognition of the survival migration status would ensure that civil, economic and social rights would be respected."

KINDNESS OF STRANGERS

The paper is based on a case study of Zimbabweans living in South Africa and Botswana. An estimated 2 million Zimbabweans have fled their country since 2005 - for many, resorting to the only available means of survival, Betts says.

Yet only 10 percent of Zimbabweans arriving in South Africa have been officially recognised as refugees.

As part of their research, Betts and his co-author Esra Kaytaz tracked down more than 3,400 Zimbabweans who had taken refuge in Johannesburg's Central Methodist Church, relying on the clergy's goodwill for shelter.

Among the group were more than 100 unaccompanied minors as well as pregnant women and people suffering from HIV/AIDS, cholera and tuberculosis.

"The government's main response to the church has been to try to forcibly clear the building, and local businesses are litigating to have the church emptied," the report said.

Betts says the legal quandary faced by these Zimbabweans is shared with many groups of Congolese, Somalis, Haitians, North Koreans and Iraqis, among others.

Although he said it would be tough to get states to endorse "survival migration" as a legal definition, he noted the success of attempts to protect other groups who have also been forced from their homes - in particular internally displaced people (IDPs), or those who have been uprooted within their own borders by violence or persecution.

An attempt to address the needs of survival migrants could draw upon the precedent of the United Nations' "Guiding Principles on Internal Displacement", which was drafted in 1998.

Though not legally binding in themselves, they consolidate states' existing responsibilities under international human rights law within a single "soft law" document.

The need to protect the rights of IDPs, who outnumber refugees globally, has prompted African countries to consider adopting a ground-breaking convention that will for the first time provide internally displaced people with similar rights to refugees.

"There are a number of reasons to be optimistic," Betts said. "The new realities of forced migration - climate change, livelihood collapse, state collapse - underpin the fact that the definition of refugee under the 1951 convention is not adequate. There's a growing acceptance that something needs to be done to supplement the convention."

The paper, "National and international responses to the Zimbabwean exodus: implications for the refugee protection regime", is due to be published on the website of the U.N. refugee body, UNHCR.

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