Over that period alone an estimated 6.8 per cent of the continent's elephant population was wiped out by the illegal ivory trade.
In central Africa, the worst-affected region, poaching led to a 63.7 per cent fall in elephant numbers between 2002 and 2012.
Evidence suggests a strong link between the slaughter, the price of ivory and increasing demand in China where carved ornaments made from elephant tusks are highly prized.
Researchers writing in the journal Proceedings of the National Academy of Sciences suggest the very existence of the African elephant is threatened.
The team led by Dr George Wittemyer, from Colorado State University, conducted a survey of elephant carcasses in Kenya's Samburu National Reserve and found poaching rates were strongly associated with local market prices for ivory and a rise in of seizures of ivory bound for China.
The researchers concluded: "Our analysis demonstrates the heavy toll illegal ivory trade is taking on African elephants, and suggests current off-take exceeds the intrinsic growth capacity of the species."