Imagine It's The Year 2045. Will The Syrian Refugee Crisis Be Resolved?

It's a distinction no country wants. In its most recent report on global trends, the U.N.'s refugee agency reported that Syria last year "had become the world's top source country of refugees, overtaking Afghanistan, which has held this position for more than three decades."

Since 1979, Afghans have been fleeing their country due to war, political repression, food shortages and lack of opportunity. It's the "largest protracted refugee situation" in the world, the U.N. says, with no end in sight.

It prompts an uncomfortable question: Could the world still be grappling with a Syrian refugee crisis decades from now?

The similarities between the Syrian and Afghan situations are noteworthy.

Since 2011, 4.1 million people have fled Syria. In the first two years after the Soviet Union invaded Afghanistan in 1979, some 3.7 million Afghans fled to neighboring countries, accounting for more than half the total number of Afghan refugees fleeing in the past 36 years.

Afghans are still on the move today. After Syrians, Afghans make up the highest number of migrants landing in Europe now, with 40,000 arriving this year alone.

But the European refugee numbers are a small fraction of those closer to home. In the cases of both Afghanistan and Syria, neighboring countries have borne a disproportionate share of the refugee burden. In Syria's case, 95 percent of refugees have fled to Jordan, Lebanon and Turkey. All three countries are feeling the strain.

For Afghans, the main destinations have been Iran and Pakistan. These neighbors, despite their hospitality, have had limited resources to assist the huge numbers of Afghans.

Iran still hosts about 950,000 Afghans, and Pakistan hosts about 1.5 million. And those are just the officially registered Afghan refugees. There are an estimated 2 million additional Afghans in those two countries who are unregistered, which would put the actual number at somewhere around 4.5 million.

Many Afghans have gone home since the U.S.-led invasion that ousted the Taliban in 2001. Nearly 6 million have returned from Pakistan alone since 2002.

Many more would prefer to go home, if conditions were better. And over the years, neither Pakistan nor Iran has been shy in expressing the wish that they would. Afghan refugees in both countries, despite being there in some cases for generations, are frequently harassed, persecuted or forced to leave.

Fifteen years ago, Pakistan shut its border in an attempt to stop the flow of Afghans coming across. Around the same time, Iran deported thousands of Afghans. This was at the height of Taliban rule, a period when Afghanistan was an international pariah, cut off from the world, unwilling to educate girls and overwhelmingly dependent on international aid.

There are other examples of large-scale, long-term refugee populations, notably the Palestinians. The Palestinian refugees now officially number more than 5 million and were displaced starting in the 1948 Arab-Israeli war. Their needs are not handled by the main U.N. refugee agency, the U.N. High Commissioner for Refugees, but by a separate U.N. body dedicated solely to Palestinians, the U.N. Relief and Works Agency.

The most common figure experts cite for the average length of displacement caused by conflict is 17 years, apparently originating from a 2004 U.N. report referring to an estimate made for refugee populations in 2003.

It's impossible to predict how long the Syrian war will last or how long millions of Syrians will remain displaced. But the Afghan experience and others suggest it could be many years, if not decades. In the meantime, what lessons can be drawn from Afghanistan's experience?

The obvious remedies are political and must embrace a long-term perspective, says Sharon Waxman, a former State Department official who served for the past three years as the International Rescue Committee's vice president of public policy and advocacy.

"Solutions to internal displacement and refugees require a political decision coupled with a development strategy — ending a conflict, absorbing them into a community or allowing them to resettle in another country," she told NPR. "That takes a long time. It requires leadership and political will and good governance and development dollars."

And while development dollars may sound straightforward enough, this is actually at the heart of the challenge: Policymakers do not treat refugee crises as a development issue requiring long-term strategies and support. They approach them as short-term humanitarian emergencies.

But it's the wrong approach, Waxman says.

"Humanitarian budgets are smaller than international development budgets," Waxman says. "There is never any long-term development strategy. They should go hand-in-hand. The challenge is when governments can't or won't meet the needs of their own people and displaced populations."

The United Nations' Sustainable Development Goals, broad development priorities for the next 15 years that follow up on the Millennium Development Goals covering the past 15-year period, are "conspicuously silent about human displacement, even though it inarguably poses insurmountable challenges to governments' ability to implement the goals," Waxman noted this week in the Huffington Post.

"People live in camps forever and are never integrated into a host country's long-term development. Countries don't want to officially absorb them," she adds.

Integrating refugees into new countries is politically challenging, and resettlement in a third country is rarely an option. Less than 1 percent of the world's refugees are resettled.

"When we draw up development plans," Waxman says, "we should focus on areas where people need and want to return. Otherwise, they live in perpetual limbo."