The migrant crisis will never end.

The immolation of Syria was the biggest cause, but on the other side of the world, two million people fled the path of Boko Haram’s pitiless offensive in Nigeria; another 2.2 million escaped civil war in South Sudan. In the terse phrase of the International Institute for Strategic Studies (IISS), which compiled the figures, this amounted to a “quantum leap in forced displacement”.

Today’s wars generally create far more refugees than previous conflicts. It may sound strange, but that is not necessarily bad news. After all, the biggest reason is simply that even the most volatile countries have also experienced rapid population growth.

Had civil war broken out in Syria in 1970, the refugee crisis would have been a fraction of today’s catastrophe. Back then, Syria had only six million people, compared with at least 20 million today.

If Boko Haram had swept across northern Nigeria in 1970, the Islamist gunmen would have been ravaging a country with barely one quarter of today’s population. The refugee camps across the border in Chad would have been tiny by our standards.

There are more refugees because there are more people – and, in turn, there are more people because the world has broadly succeeded in reducing infant mortality and raising life expectancy, even in the poorest countries.

Many of those improvements, incidentally, were driven by the aid programmes of the very European countries that now find themselves inundated with refugees. The EU and its members have spent huge sums on primary health care and childhood vaccination campaigns across Africa and the Middle East. The result is that more children live to become adults, the population rises – and so does the number of people who are vulnerable to becoming refugees if war breaks out.

The volume of migrants heading for Europe is not solely because of war and poverty. The affected countries also have many more people than in the past – partly because Europe did the right thing by, for example, eradicating smallpox and immunising children against polio.

All this means that our understanding of the “migration crisis” will need to change. The very word “crisis” is misleading for it implies a passing moment of danger that will eventually come to an end.

But the central causes of the outflow of refugees from Africa and the Middle East are not transient, but structural. In its latest Armed Conflict Survey, the IISS casts around for policies that might stop people from fleeing war zones and ends up resorting to platitudes, like placing “effective pressure” on Bashar al-Assad to obey “international humanitarian law” as he tears Syria to shreds. Some chance.

The IISS also urges “better access for humanitarian relief in the country of conflict” so that people are not compelled to leave simply to find food and shelter. Again, some chance. The likes of Boko Haram or the Islamic State of Iraq and the Levant (Isil) are never going to allow a free pass for aid workers in their bloodsoaked domains.

Wars will always force large numbers of people to flee. Populations are generally growing, so future conflicts will create even more refugees than today. If 46 million people are now living in camps or other sanctuaries, the conflicts of the 2020s are likely to displace still more.

Instead of being a passing phase, the “migration crisis” is part of the fabric of the world.

Telegraph