They're The Invisible Ones: Refugees Who Aren't Officially Refugees

The image of refugees crammed in a boat crossing the Mediterranean was one of the iconic pictures of 2015. Some 13 million people were tallied as refugees last year by the United Nations High Commissioner for Refugees, fleeing violence or disaster in their home countries.

But another 27.8 million people were displaced from their homes in 2015: 8.6 million because of armed conflicts and another 19.2 million due to natural disasters.

But they're not counted in the refugee numbers. That's because they stayed in their in own country, so they aren't officially categorized as refugees.

Alexandra Bilak, the interim director of the Norwegian Refugee Council's Internal Displacement Monitoring Center says the plight of internally displaced persons — known as IDPs — has become a global crisis.

"The total number of people who are internally displaced by conflict and violence has reached the highest level we've ever recorded," she says. And in some ways, they're even worse off than the world's burgeoning refugee population. A new report from the council documents the situation country-by-country in 2015.

Bilak says it's often more difficult to get international aid to IDPs than it is to help refugees. IDPs are often stuck in the country where violence is still raging, and aid groups may be unable to reach them.

"In many conflicts, there's a problem of access. The displacement itself becomes a huge political issue. Accessing these populations and even knowing where they are can be difficult," she says.

Many times people become IDPs because their government is unable to protect them and keep them in their homes in the first place. At other times their government may have been actively involved in attacking them. The regime in Syria has been repeatedly accused of bombing its own people.

The greatest number of IDBs in a single country in 2015 was in Yemen, which is currently in the throes of conflict.

"The majority are not living in camps," Bilak says. "There's very little camp infrastructure in Yemen. The majority are living in overcrowded rented accommodations. Many have moved into schools and public spaces. Some are in tents or makeshift shelters. They're exposed to harassment and gender-based violence. They're suffering from food insecurity. Their children are no longer going to school."

After Yemen, Syria and Iraq were the next two countries producing the largest number of IDPs in 2015. Millions of people have fled Syria and Iraq as refugees but just over a million were displaced internally in both countries last year, according to the council's report.

Fighting in Ukraine, Afghanistan and Nigeria also forced significant numbers of people from their homes.

"These people are extremely vulnerable because they're not getting adequate protection from their government," Bilak says. "Also they're not getting protection by an international system as refugees would. Many IDPs actually fall through the cracks."

And then there are the disasters. The Nepal earthquake pushed 2.6 million people from their homes last year.

Bilak says recovery from natural disaster is usually faster than from war but still depends on government officials having the political will and the resources to help people return and rebuild their homes.

"Internal displacement is very often protracted," she says. "Many people remain displaced within their country for years and years, sometimes even decades."