VANCOUVER—With Africa’s rhino population imperilled and the price of their horns worth more than gold, a group of scientists have argued that it’s time to regulate the trade and harvesting of rhino horns.

In this week’s Science journal, scientists say that carefully legalizing trade based on humane and renewable harvesting of the white rhino horn could stem encroaching extinction. At the current rate of poaching, Africa’s remaining rhino population could become extinct within the next two decades.

“As committed environmentalists we don’t like the idea of a legal trade any more than does the average member of the concerned public,” said the journal’s lead author, Duane Biggs at the Australian Research Council Centre of Excellence for Environmental Decision.

“But we can see that we need to do something radically different to conserve Africa’s rhino.”

The trading of rhino horns, composed of the protein keratin and found in human skin, hair and fingernails, has been banned since 1977.

But poaching continues to accelerate, more than doubling each year since 2007, driven partly by the skyrocketing costs of rhino horns. In 1993, it cost $4,700 per kilogram for rhino horns and today the price is around $65,000 per kg, which makes its worth more, per unit weight, than cocaine, diamond or gold.

Thefts from museum specimens of rhino horns in Europe have been linked to the rising demand for the animal part, which is used in dagger handles in Yemen and in traditional Chinese medicine.

Rhino horns, which naturally grow back when shaved, could reduce the illegal trade of the horns, Biggs said in the journal. Sedating a rhino can be done for as little as $20 and the annual horn production of one white rhino averages 0.9 kg per year. The scientists say the risk of dehorning is minimal and there is limited evidence of significant behavioural change from the animal following dehorning.

It has been done before: poaching pressure in the trade of crocodile skin was reduced after governments allowed crocodiles and alligators to be farmed for their meat and their leather.

“Legitimizing the market for horn may be morally repugnant to some, but it is probably the only way to prevent extinction of Africa’s remaining rhino,” the scientists said.

In a statement, Water and Environmental Affairs Minister Edna Molewa of South Africa said the feasibility of dehorning all black rhino and key white rhino populations as an option to prevent the illegal trade is questionable due to the challenges and costs of the undertaking. The government also has some concerns about the commercial farming of rhino connected to genetic management and impact on range expansion.

Since the beginning of the year, the government noted 128 rhino have been poached in South Africa and a total of 46 people have been arrested so far this year for rhino poaching.