St. Augustine, Fla. ? Facing the old slave market from the sea, you can try to imagine what it was like to arrive here as a captive in the 1500s, with a future of forced servitude as your fate. You can try, but you can never grasp the totality of the horror. In those long-gone days, ships sailed right up to the market and unloaded their cargo, including human beings. Slavery, though legal then, was loathsome.

It still is. Even worse, after nearly a half-millennium, slavery (also known as human trafficking) — though illegal everywhere — is sickeningly prevalent across the world. More people than ever endure its shackles, living under a perpetual threat of violence and only dreaming about freedom. Their number ranges close to 30 million. Yet, they are typically as faceless and voiceless as their predecessors were over the centuries.

Why does slavery persist?

The reasons are complex and varied. In the simplest of terms, however, it is because too many people continue to harbor feelings of superiority toward others and willingly subjugate them. Further, too many hypocritical governments pretend to care about human-trafficking victims even as they wink at slave-traders. Also, in a globalizing world, too many opportunities exist to exploit human beings, a problem multiplied by greed, corruption and, most recently, the recession.

Life has been cheap — shamefully so — in recent decades. Today, though, as hard as it is to believe, the average cost of a slave has dropped below $100. At that price, people become essentially disposable. If a slave disobeys, fails to perform, tries to escape or otherwise falls into disfavor, the solution is easy and commonly without consequences for the slave-owner. Because many slaves have already had their identities erased, their premature passing fails to register.

Still, justice beckons. For nearly a decade, the U.S. government has closely monitored and reported on human-trafficking trends, criticized governments with lax anti-slavery records and pushed for greater global cooperation. In addition, the issue holds special interest for the Obama administration. Well before they took office, President Barack Obama, Secretary of State Hillary Clinton and other senior administration figures were voicing their disgust for human trafficking and cheering efforts to combat it.

Clearly, the moment is opportune to raise the human-trafficking problem to a much-higher priority, with the goal of moving aggressively toward eliminating this despicable practice. Three steps by the Obama administration during the coming year would propel us in that direction:

1. Unequivocally declare the goal of ending slavery in our time. Obama should make a high-profile speech devoted exclusively to the topic of human trafficking as both a U.S. and global phenomenon. Realistically, some elements of slavery would survive, but many abolitionists believe — and I think they are on target — it is possible to suppress the bulk of it within a few decades.

2. Announce a presidential task force, packed with appropriate expertise, to investigate contemporary slavery. Such a group would be instrumental in developing a broader counter-slavery strategy. The United States must have an integrated, comprehensive plan for dealing with slavery. Its focus should be on preventing the problem, protecting victims and prosecuting slave-traders.

3. Carry the message of urgent eradication to the world. Using his personal appeal and power of persuasion, Obama should make full use of opportunities at the United Nations and on trips abroad to remind people of the collective responsibility they have to resolve the slavery problem. Not all countries would be willing to follow the U.S. lead, but I think most would.

Now, I am sure some people will ask why a president who clearly has his hands filled with major challenges such as the recession, terrorism, climate change, foreign wars and a worrisome influenza would add slavery to his list. Simply put, because it, too, is a major challenge. Moreover, slavery is morally wrong, inexcusable and an abomination. That it still exists and thrives in the 21st century should be acceptable to no one.