By William Lacy Swing, Director General of the United Nations migration agency, the International Organization for Migration (IOM)

NEW YORK—Two centuries ago, right here in this city soon to emerge as the world’s center of commerce, a coalition of clergy, government officials, business leaders and rescued victims rose to fight the scourge of human slavery.

Their cause was Abolitionism and it became the world’s first transnational human rights movement.

Thanks to Abolitionism, businesses that depended on human bondage would no longer be tolerated. Soon they would be illegal. Slavery, which had endured since antiquity, was driven first from the English-speaking world and, eventually, everywhere else.

Or was it? We are here this week to examine a problem that’s risen in today’s increasingly globalised economy. To put it in blunt terms, the “chains” of historic slavery have in some cases been replaced with invisible ones: deception, debt bondage, unethical recruitment. It may be an infection buried within the supply chains of sophisticated global industries—like fishing, logging or textile manufacturing.

Or it can be hidden in plain sight—on any street corner where sex is sold for money.

Its victims number in the tens of millions. At any moment in 2016 forced labor—and its twin scourge, forced marriage—enslaved an estimated 40.3 million men, women and children worldwide, this according to research being released here this week during the opening of the United Nations General Assembly.

While many consider slavery a phenomenon of the past, it is a plague that is still very much with us. Criminals worldwide continue to find new ways to exploit vulnerable adults and children, undermine their human rights and extract their labor by force. Whether this takes the form of the sexual enslavement of women or the recruitment and trafficking of men forced to labor, no continent, and no country, is free today of this threat to human rights and human dignity.

On 19 September, Alliance 8.7, the global partnership to end forced labor, modern slavery, human trafficking and child labor, will bring together key partners representing governments, United Nations (UN) organizations, the private sector, workers’ organizations and civil society to launch new global estimates of modern slavery and child labor.

The global estimate of modern slavery was developed by the International Labor Organization (ILO) and the Walk Free Foundation, in partnership with my organization, the International Organization for Migration (IOM), which is also the United Nations global migration agency.

Accurate and reliable data are vital tools in tackling complex social challenges like modern slavery. The estimates prepared by Alliance 8.7 will not only raise international awareness about such violations, but will also provide a sound basis for policymakers around the world to make strategic decisions and enable development partners to address funding gaps.

Drawing on in-depth responses from thousands of face-to-face interviews conducted in 48 countries, combined with comprehensive data sets about the experiences of victims of human trafficking from the IOM, the global estimates of modern slavery will provide valuable insight into the numbers behind modern slavery with specific information regarding region, group and gender.

Among the findings to be presented here this week:

Since 2012, 89 million people experienced some form of modern slavery, some for periods as brief as a few days, others for many years.

Debt bondage affected half of all victims of forced labor.

Women and girls accounted for 71 per cent of total modern slavery victims.

One in four victims of modern slavery were children.

Such data, sadly, reveal only one facet of this ongoing tragedy: its global scale. The hard work of rescuing victims reveals how deeply modern slavery affects whole families.

Recently, IOM’s Global Assistance Fund for victims of trafficking and other migrants in vulnerable situations contributed to assisting 600 men from foreign fishing boats enslaved in Indonesian waters. Some had not been on dry land for years. One victim told IOM he had been separated from his family, without any contact, for 22 years.

There should be no mystery as to why this has become such a concern of IOM. We call for migration that is safe, legal and secure for all. Safe and legal migration means mobility managed transparently by the world’s governments, instead of hidden in a labyrinth of criminal netherworlds.

Migration that is secure for all means just that: for all. Governments need not wonder who is sneaking tonight across some unguarded border. Employers need not worry their new hire is, unknown to them, a debt-slave bound to a “recruiter” who is pocketing their pay—even as he or she increases the debt burden on the victim. Families need not dread what has become of a son, or daughter, who leaves home for a distant opportunity—and then is never heard from again.

So please join me in this fight against global slavery. The struggle may be centuries old but, in some ways, it’s just beginning.