REFUGEES are barometers of violence. Their increase, says the UN High Commissioner for Refugees (UNHCR), António Guterres, shows that armed conflict round the world really is getting worse—the impression is more than just anecdote. According to his organisation, at the end of 2013 more than 50m people had been forced to flee from their homes (see chart). It is the largest count ever, an increase of 6m, or 13%, over 2012—and the sharpest rise for decades. There are now as many displaced people as the populations of Spain or South Africa.

The main explanation is the war in Syria, which has produced more homeless people than any other recent conflict—9m, almost half the pre-war population. Nearly 3m of those have crossed borders in order to throw themselves on the mercy of aid agencies or foreign states (mostly Turkey, Lebanon and Jordan). They are defined as refugees. The rest have stayed miserably within the country that has made them homeless and are called internally displaced persons.

Syria has produced more refugees than any other conflict of the past two decades: more than the genocide in Rwanda (2.3m refugees in 1994); the war in Kosovo (800,000 in 1999) or the post-war period in Iraq (at least 300,000 in 2006-13). Syria used to be one of the likeliest hosts for other countries’ refugees (mostly from Iraq). It has become the largest producer of refugees after Afghanistan—testimony to the exceptional brutality of the Syrian conflict.

This is not the only explanation, though. The civil war in the Central African Republic (CAR) displaced 800,000 people within the country and almost 100,000 who fled to neighbouring states. Strife in Mali is in its second year, and in Somalia in its fourth. The persistence of old wars explains much of the rest of the growth in the number of refugees.

In the past, many refugees were able to go home after a year or two. In the early 1990s, between 2m and 3m exiled people went back to their old homes each year. The number of those returning is now below 500,000 a year and has been for several years. A few more refugees have been able to resettle in a new country—mostly in the West—but the overall figure is so tiny (fewer than 100,000 in 2013) that it makes little impact. The result is that most refugees are stuck for years. At the end of 2013, more than half of all refugees had been in exile for five years or more.

Over the past 20 years most measures of state or public violence—such as the number of interstate wars and the rate of battle deaths—have been declining. Why then are there so many refugees and internally displaced people? In fact, there is a difference between the two groups. The number of refugees has indeed been declining. In the early 1990s the UNHCR was directly looking after more than 15m refugees worldwide; now it is caring for 12m. That change is consistent with the long-term decline in violence.

But the number trapped within conflict zones has soared. In 2013 the UNHCR was helping nearly five times as many internally displaced people as in 1993, almost 24m. They may be victims of the changing nature of conflicts: fewer wars between states but more violence associated with the collapse of states (such as Syria, Somalia and the CAR). Sometimes that collapse can be frighteningly fast, trapping people before they can get abroad. In just two weeks, more than 300,000 people have fled into Kurdish parts of Iraq from Mosul after it was captured by fighters from the Islamic State of Iraq and Greater Syria, an extremist group. They have nowhere else to go.