Twenty years ago tomorrow, Kenya’s president Daniel arap Moi lit a bonfire of 2,000 elephant tusks in Nairobi National Park as a dramatic gesture to signal his country’s stance against the trade in illegal ivory. Photographs of the huge blaze, with its black smoke curling skyward, appeared around the world and the event came to symbolize global revulsion against ivory poaching—and the killings that halved the African continent’s elephant population in single decade.

A few months later, in October of 1989, member countries at a CITES meeting in Lausanne, Switzerland decided to halt international trade in ivory. The ban came into effect at the beginning of 1990.

But it’s not easy to get rid of ivory—in fact, it took 60 tons of firewood and forty gallons of gasoline to ignite Moi’s twenty-foot stack of tusks. And it’s impossible to eliminate all trade in ivory—because bad as the illegal trade in ivory is for elephants, legitimate, regulated trade in ivory can actually help them.

How? Ivory is something elephants leave behind when they die of natural causes, and tons of it is routinely stockpiled by African nations. Those countries that do a good job of managing their elephant populations (as evidenced by their growing herds) have twice successfully petitioned CITES to allow “one-off” sales of their legitimate ivory stockpiles to raise money for elephant conservation.

The most recent sale, in October of last year, raised some $15 million dollars for South Africa, Namibia, Botswana and Zimbabwe. As part of the deal, these four nations were prohibited from petitioning CITES to sell additional ivory for nine years.

Much of the media misunderstood this critical detail, and asserted that all trade in ivory had been halted for another nine years. However, African countries that were not part of this “one-off” sale aren’t restricted from submitting proposals to sell their ivory stocks. Sources tell me CITES expects to hear from Tanzania, Zambia and Mozambique at its next meeting in March, 2010.

The role of ivory in elephant conservation is a contentious issue, and will likely remain one for years to come. But in a shrinking world, elephants can’t wait forever for solutions. Ways must be found to suppress illegal elephant killings that feed the black market in ivory. At the same time, steps have to be taken to allow limited, highly controlled exports of legitimate ivory from countries that deserve to benefit from their successful efforts at protecting their elephants.