Cold War Radioactivity Can Date Illegal Elephant Ivory

Wed, 2013-07-03 16:24 by Hans

New technique may allow countries to track illegal sales.

Roff Smith
for National Geographic

Read the complete article in National Geographic

Fallout from long-ago Cold War explosions is now a forensic tool in the very modern war against elephant poachers and the illegal trade in ivory.

It's a war that's never been hotter. Despite a 1989 international ban on ivory sales, elephant poaching is a bigger business than ever, with an estimated 30,000 African elephants being killed for their tusks last year alone—a rate of slaughter, say wildlife experts, that could drive the majestic animals to extinction within the century. (Explore a map of dwindling African elephant populations.)

Much of the ivory is destined for China and the Far East, where it can fetch upward of $1,300 a pound. (Read about blood ivory in National Geographic magazine.)

Law-enforcement officials trying to stem the tide have had to contend not only with highly organized criminal gangs, but also with complexities in international law that allow ivory acquired before the 1989 ban to be legally bought and sold.

Trying to distinguish legal (pre-1989) ivory from poached (post-1989) ivory has been nearly impossible—until now. (Related: "In Global First, Philippines to Destroy Its Ivory Stock.")

A new ivory-dating technique, described this week in the journal Proceedings of the National Academy of Sciences, relies on radioactive isotopes released into the atmosphere during atom bomb tests in the 1950s and '60s. A ban on aboveground nuclear testing went into effect in October 1963.

Known as bomb-curve dating, the technique allows scientists to detect radioactive isotopes within ivory or tusks and thus determine to within a year the time the elephant died or was killed. The bomb curve is the fluctuating concentration of carbon-14—a heavily radioactive isotope—in the atmosphere since the 1950s.

"This will tell us the age of the piece and thus whether or not it was acquired legally," said study leader Kevin Uno, a postdoctoral researcher at Columbia University's Lamont-Doherty Earth Observatory.

"It is a simple, accurate, and affordable test and will make it far easier to enforce the ivory ban."

How does bomb-curve dating work?

Read the complete article in National Geographic