Studying carbon accumulated in tusks during nuclear weapon tests can help scientists tell if ivory was acquired legally
Measuring the age of carbon that came from nuclear weapons tests in the 20th century could help conservationists detect illegal ivory and pinpoint poaching hotspots, according to new research.
Despite the 1989 ban on the ivory trade, the illegal poaching and slaughter of elephants is still rife in many areas of Africa, leading Barack Obama on Monday to announce $10m to train police officers and park rangers to combat the illegal trade.
The new application of a technique known as "bomb-curve 14C dating" is applied to the carbon contained in both collagen and the mineral apatite within ivory to provide an age of death of the animal from which the ivory originated.
Such dating relies on the dramatic increase and subsequent decline of 14C - an isotope of the naturally occurring element carbon that radioactively decays with time – in the atmosphere since the 1950's related to the testing of nuclear weapons during the 1950-1960's. Much like the growth rings used to date the age of trees, elephant tusks also grow in rings recording the composition of carbon in the atmosphere at the time the animal was alive and consuming plants that had absorbed atmospheric carbon during growth.
The study's lead author, Kevin Uno, a postdoctoral researcher at Columbia University's Lamont-Doherty Earth Observatory, said: "We've developed a tool that allows us to determine the age of a tusk or piece of ivory, and this tells us whether it was acquired legally. Our dating method is affordable for government and law enforcement agencies and can help tackle the poaching and illegal trade crises."
If confiscated ivory of unknown origin measured by this technique is determined to to be "modern" in age (post-1989) then it mostly likely originates from an illegal source. Combinedwith existing techniques that can pinpoint the geographical location of the ivory, it could help to better direct conservation efforts to the locations most affected by poaching. The research was published on Monday in the journal Proceedings of the National Academy of Sciences.
One of the main obstacles for the researchers to overcome was in finding the legal ivory on which their technique could be tested. This involved working collaboratively with Salt Lake City zoo and agencies in Kenya to obtain ivory from elephants who had died of natural causes. The technique applied by the researchers - accelerator mass spectrometry - allowed them to measure the very low abundances of 14C to a high level of accuracy to date the time of the animals death to within two to three years.
The researchers say that the technique is fast and affordable at around $500 a sample, meaning that it can easily be used by governments and law-enforcement agencies to tackle the locations where illegal poaching continues. Uno said: "this is not much money when you consider that it's a multibillion dollar industry and the price to future generations of losing the elephants is surely much worse."
Escalating ivory prices are thought to be responsible for driving African militias into poaching. Hilary Clinton spoke out last year about the associated organised crime in smuggling of ivory out of Africa into the US which is the second biggest market for ivory in the world, behind Asia, and in May Prince Charles called for a war on poachers.
Still stricter laws are being called for to help prevent the continued poaching of wild animals. Experts say that more elephants are slaughtered every year now than before the 1989 ban – leaving an estimate of just 423,000 African elephants in the wild.