The Climate Change, Vulnerability and Human Mobility report, based on discussions with around 150 refugees and internally displaced people in Ethiopia and Uganda in 2011, is published by the Office of the UN High Commissioner for Refugees (UNHCR) and the UN University (UNU).

Most refugees reported that leaving their homes was a last resort and their first displacement was temporary and to an area close to home.

However, the majority of refugees fled their countries after the ares they moved to were affected by insecurity, violence or drought.

“This report confirms what we have been hearing for years from refugees,’’ said the High Commissioner for Refugees, António Guterres, who introduced the report while attending the Rio+20 UN Conference on Sustainable Development in Brazil.

"They did everything they could to stay at home, but when their last crops failed, their livestock died, they had no option but to move, movement which often led them into greater harm's way," he stated.

Most of those interviewed for the report were farmers and pastoralists from Eritrea, Somalia and eastern Sudan. They were asked questions about the extent to which climate change contributed to their decision to leave their homes, and their countries.

Whilst many refugees described disrupted rainfall patterns in the past decade, with longer and more severe droughts than in previous years, none said these negative shifts in weather as a direct catalyst for violent conflict.

Some did, however, cite the scarcity of food and crops after severe drought as exacerbating pre-existing conflicts, persecution and repression.

While many people displaced as a result of extreme weather conditions stay within their national borders, those that cross international borders are not necessarily covered by the 1951 UN Refugee Conventin. This treaty forms the legal foundation on which UNHCR’s work is based.

The Convention defines those who qualify as a refugee, a person with a well-founded fear of being persecuted for reasons of race, religion, nationalisty, membership of a particular social group or political opinon, and underlines the rights and obligations between host countries and refugees.

The Nasen Initiative, to be formally launched in October 2012 by Norway and Switzerland with the support of UNHCR and the Norwegian Rufugee Council, aims to address the legal and protection gap for people displaced across borders because of environmental change and extreme weather conditions.

"I am convinced that climate change will increasingly be a driver in worsening displacement crises in the world," said the High Commissioner, Mr. Guterres.

"It is very important for the world to come together to respond to this challenge."