LONDON – Voters in the United Kingdom have done the unthinkable, choosing to leave the European Union – a truly noble project that, whatever its shortcomings, has promoted peace and stability across the continent for more than a half-century. Markets have tumbled, Britain’s prime minister has announced that he will resign, and the UK is more divided than ever. And the consequences – for the UK, the EU, and the world – may be just beginning.

The “Brexit” vote represents a triumph of fear over reason. “Leave” campaigners mendaciously and recklessly capitalized on popular distrust of the ruling elites and discontent about growing inequality and rapid social change to advance their own interests. In a relentless anti-immigration campaign, the Brexiteers, together with tabloid media, peddled distorted facts and outright lies about the impact of migration, thereby convincing fearful and frustrated voters that immigration and the EU, which requires freedom of movement among member states, are responsible for virtually all of Britain’s social woes. Many of the Leave campaign’s leading actors have been antagonistic toward the EU for decades.

It is a trend that can be seen in much of the developed world. Populist demagogues are arguing that migration is draining national resources and eroding national sovereignty. The only way to regain control, they claim, is to batten down the hatches and retreat from international alliances, behind national borders.

It is not that all of the those who voted to leave the EU, or others around the world who also feel left behind, were acting simply out of intolerance and extreme nationalism. But many have embraced the ludicrous story, served up by the populists, that their countries are being overrun by migrants, who will exacerbate the social and economic challenges that they face. In Europe, the refugee crisis in the Mediterranean – fueled largely by the forced displacement of people fleeing war and criminal violence – has heightened such concerns in recent months.

A cool-headed debate on migration first requires challenging the corrosive narrative promoted by xenophobes. The truth is that, far from being a drain on a country’s budget, migration can inject new dynamism into aging host societies. While integrating migrants undoubtedly presents challenges, they can be overcome.

But, so far, the positions taken by some members of the international community, especially the EU, have undermined an adequate collective response to the refugee crisis. And yet the EU has suffered a failure not of its institutions, but of many of its member states. In fact, the European Commission has proposed largely appropriate responses to the crisis, and many member states, especially Germany and Sweden, have responded adequately.

German Chancellor Angela Merkel, in particular, has urged EU members to show human decency and abide by their international obligations to protect asylum-seekers. Yet leaders in other EU member countries, particularly in Central and Eastern Europe, have not demonstrated anything close to constructive leadership.

Around the world, 250 million people are living outside their countries of origin. Sixty-five million were displaced by conflict, natural disaster, and other dire circumstances. So far this year, some 227,000 people have reached Europe by land or sea. Nearly 3,000 more have drowned in the Mediterranean while attempting to reach safety. Tens of thousands of migrants and refugees are still stranded at the edge of the continent.

It is a humanitarian crisis. Yet many wealthy states have yet to live up to their obligations and to fulfill even their limited pledges on resettlement. As the Brexit vote makes painfully clear, it is time for the international community, and especially the EU, to change its approach to migratory flows, or it could face even higher costs.

Crucially, no one is arguing in favor of uncontrolled migration. Instead, advocates of migration, including me, promote protection for refugees and managed flows of people by making legal pathways more accessible. This will require international-level cooperation, backed by the right national and local measures.

Such an approach would involve improved border controls, but its focus would extend far beyond limiting migrant inflows to include creating opportunities and providing enough resources to public services to mitigate the new arrivals’ impact and ensure that local residents are not disadvantaged by welcoming migrants into their communities. Germany recently adopted new measures to provide language training and facilitate the integration of refugees. In Canada, communities can embrace new arrivals through private sponsorships.

Research shows that the initial investment can be recouped in as little as five years, thanks to the increase in economic activity brought about by the newcomers. The key is to enable legal migration. That way, instead of allowing smugglers and exploitative employers to pocket billions at the expense of migrants, states can collect more taxes through formal employment.

A bold new vision, bolstered by committed leadership, is urgently needed to tackle these complex issues, offering reassurance to voters and thus preventing more countries from turning inward and jeopardizing decades of multilateral progress on human rights. As the ripple effects from the British referendum are demonstrating, no country – not even the UK – is an island in today’s globalized world.

There is reason for hope. The fact that Britain’s younger generation voted overwhelmingly in favor of remaining in the EU suggests that traditional perceptions of national identity and sovereignty do not have the same emotional hold on millennials as they do on older generations. Brought up with greater access to the outside world through travel and the Internet, young people are more at ease with cultural diversity and multiple identities. They also have a better understanding of the opportunities that globalization offers, even if youth employment remains a chronic problem in many countries.

Like Britain’s young people, we must look to the future, not the past, and embrace international cooperation, not isolationism. The task of devising innovative solutions is daunting, but a better approach to migration – one that benefits everyone involved – can be achieved. The alternative is too costly, in human, political, and economic terms, to consider. Fear must not win the day.