How far we have come from the warm generosity of the German summer to the cold hard reality of a Nordic winter. Europe’s internal borders have been closing; its external borders are being reinforced. And governments are looking for ways to foot the bill for receiving and integrating all the new arrivals, many of whom have crossed deserts and seas in the hope of finding a safe haven in Europe.

The German finance minister has mooted an EU-wide tax on petrol. Danish MPs are debating a law to allow the confiscation of asylum-seekers’ valuables to help pay for their keep. It turns out the Swiss already do this.

The money, though, will have to be found. Not just because Europe is a rich continent with values and obligations to match, but because international law and the precepts of the European Union say so. Anyone arriving at another national border has the right to ask for asylum; and the receiving authorities must weigh the merits of that claim.

The legal definition of a refugee and the criteria for granting asylum date back more than half a century. And while some will argue that they reflect universal values and, as such, should be upheld to the end of time – the concept of sanctuary, after all, has ancient roots – it is surely not unreasonable to ask some questions.

Over the past six months, as we have shared the euphoria of those rescued from leaking boats off Greece, tried to commiserate (however inadequately) with bereaved relatives, and marvelled at the fortitude of those seemingly endless columns of human beings making their way through Europe, the parallels with the past have seemed obvious.

This is, we are told, the greatest movement of people in Europe since 1945. Scenes of desperate people blocked by police at barbed-wire fences, hundreds forced on to trains destined only for the next siding; whole families sleeping in the open at night; teenage heroes pushing family members across continents in wheelchairs: here were reminders of the darkest chapters of Europe’s 20th-century history.

For all the echoes of WWII, there are also differences – and they cry out for the current provisions to be reviewed

It was the plight of the millions of displaced people at the end of that war, and the need for an orderly system of resettlement, that spurred the talks that resulted in the Geneva refugee convention of 1951. And it was the spectre of European history seeming to repeat itself that convinced Angela Merkel that a different Germany had to show its face.

Yet for all the echoes of those times, there are also differences – and those differences cry out for the current provisions at very least to be reviewed.

In its principles, the codification of refugee status in the Geneva accord looks as relevant today as it was when it was first drafted – and as it was in 1967, when a protocol extended its provisions globally. A refugee is defined as a person who is “outside his or her country of nationality or habitual residence; and has a well-founded fear of persecution because of his or her race, religion, nationality, membership of a particular social group or political opinion”.

To this have been added European Union provisions, including the 2013 Dublin regulation that requires someone arriving in the EU to request asylum in the first country they reach. The burden this placed on countries such as Italy and Greece, with long sea borders that are hard to police, was evident even before last summer, and encouraged blind eyes to be turned when new arrivals in Europe chose to continue their journey.

If the definition of a refugee remains as valid as it always was, however, the international context has changed to a degree where the whole system is at risk. The Geneva and EU ideals are, quite simply, not compatible with today’s reality.

Time was when those granted asylum in what was then western Europe were few and far between – persecuted opposition figures, deposed leaders, dissident intellectuals. In practice, if not on paper, the criteria were narrowly drawn. The concept seemed more like a privilege accorded to an individual, rather than an international entitlement to be extended to whole groups.

Now, travel is far easier than it was in the middle of the last century. Information – about the law and living standards (if not benefits) – is more widely spread. And, like it or not, trafficking has become a profitable industry, aided by mobile phones and mobile money.

It may still be difficult to escape a war zone, such as Syria, but once into Lebanon, or Turkey, or Jordan, the next stage and the next become easier, so long as you have money to pay. Before last autumn, if you managed to reach Greece or Italy you could travel almost unhindered to any other country within the Schengen region.

What is more, the criteria for asylum, as interpreted by human rights lawyers and applied now, make it theoretically possible for whole ethnic, religious or other groups to qualify – including almost anyone whose country is at war.

Much is made by governments of the difference between people who genuinely need a place of safety and those “merely” seeking a better life. But that distinction – as between “migrants” and “refugees” – has become more and more difficult to draw.

Do all Syrians qualify for asylum, for instance, because parts of their country are in the grip of civil war? Then what about a young Nigerian, say, who left his village to seek work in Europe but experienced unspeakable deprivation and suffering on the way? Do his experiences en route change his status on arrival from that of migrant to refugee? The answer may seem a clear no, but some lawyers would say he has a strong case.

Campaigners accuse the EU of inadvertently muddying the definitions by making it so hard for outsiders to come in. Unless “fortress Europe” offers more legal channels for non-citizens to move here, they say, people have no alternative but to try their luck illegally.

That argument is contestable. What is not is that the scale of the exodus from war-torn and maladministered countries, the desirability of the EU, and the Geneva definition of “refugee” are generating a demand that is beyond the capacity of even Germany’s generosity. Tightening definitions – a stricter interpretation of persecution, for instance, and better enforcement of the requirement to seek asylum in the first safe country reached, or more reciprocity (no fingerprints, no entry; commit a crime, summary deportation, etc) – will be nowhere near enough to alter that.

What is needed is a new Geneva refugee convention. It could limit the group qualification for refugee status, or the right of those fleeing to seek refuge outside their home region, or the length of time they may stay. It could try to guarantee places of safety for civilians in war zones. Historically the UN-approved “responsibility to protect” clause was that shield, but that too is failing. Another reason to rethink the whole thing.