Last week, Greece announced a pilot plan to install a “floating wall” in the Aegean Sea. A system of floating dams off the coast of Lesbos, spanning 1.7 miles and rising 50cm (20in) above the water, the barrier is intended to block the primary sea route to Greece from Turkey, and deter migrants from attempting the journey. But in a country with a maritime border roughly 500 nautical miles long, the floating barrier is primarily symbolic. Like Trump’s wall, it will signal the intent to keep out migrants; and like Trump’s wall it will fail to do so.

Europe’s refugee crisis no longer dominates headlines. According to the European commission, the reason is simple: the crisis is over, solved by “a step change in migration management and border protection”. The situation in Greece, however, tells a different story. Migrants still arrive at its shores, even if the rest of the world is hardly paying attention. Last year, 74,613 distress migrants fleeing conflict and destitution entered Greece, bringing the total number in the country to 112,000.

And with ongoing conflict and destitution in Syria, Afghanistan and the Democratic Republic of the Congo, arrivals show no sign of abating. Greece, a small country still recovering from a devastating economic crisis and with high levels of domestic unemployment, is not the migrants’ destination of choice. But with onward migration to wealthier countries blocked by an increasingly xenophobic European Union, the country has become the bloc’s primary buffer state, carrying the humanitarian burden for the whole of Europe.

The consequences in Greece are increasingly harsh. Close to 20,000 people are being held on Lesbos, an island of 86,000 people, crammed into a camp with a holding capacity less than 3,000. There, thousands spend months fending for themselves in flimsy tents erected in olive groves, uncertain about how and when their asylum claims will be determined, with inadequate access to medical care and education. Meanwhile a host community that provided a generous welcome in 2015 is increasingly dismayed by the failure of European migration policies, and the impact on their daily life, including the dramatic drop in their key source of revenue, tourism.

Migrants should have the option of safe channels, such as humanitarian visas, that afford orderly exit strategies

This situation is clearly untenable, with tension on the island leading to recent clashes and violence. But a wall won’t be the solution. People fleeing war, persecution, violence, famine and poverty do not abandon their plans just because of new obstacles; they persevere, if necessary by more dangerous or costly means. Despite the 654-mile physical barrier between the US and Mexico, almost a million distress migrants arrived at the US’s southern border last year.

Rather than putting up more barriers, the answer to the current situation is to address two of the key underlying problems: first, the factors that drive thousands to flee their home countries; and second, the lack of effective policies to manage humanitarian migration in a humane and efficient manner. These problems are not easy to fix and they are certainly not the responsibility of the Greek government. But as the situation in Greece so poignantly illustrates, the costs of ignoring them are unsustainable, in human, economic and political terms. The world’s richest regional union could do much better.

A starting point would be vigorous, multifaceted investment in migrants’ home countries to strengthen the rule of law and enhance economic and social development. Though complex and expensive, much could be achieved at a fraction of the what is already being spent on excluding migants and border control. Consider the EU’s current plan to double migration spending and quadruple border control expenditure for the next seven years, dedicating a total of €34.9bn to border and migration management.

Change will take time, and people will always have reasons to flee, particularly as the climate crisis worsens: in 2018 alone, 764,000 people were displaced by drought. Migrants should have the option of safe channels, such as humanitarian visas, that afford orderly and regulated exit strategies. For those deemed not to qualify for these visas, well-staffed and efficient asylum procedures should be available. Delays are not “natural”, they reflect a political decision about the value of some lives over others. Europe demonstrated those priorities across centuries of colonial domination and exploitation; it is tragic to witness that legacy in action again today.

The EU, with its enormous human and technical resources, has the means to deliver on both these challenges – it just needs political vision and leadership. Without them, we will continue to erect futile but costly walls, on land and sea.

• Vasileia Digidiki and Jacqueline Bhabha teach at Harvard TH Chan School of Public Health