The carbon-14 dates published by different researchers could not be reconciled, leading to confusion and prolonged controversy.It was an anxious time for scientists whose reputation for accurate work was on the line.Nuclear laboratories, awash with funds and prestige, spun off the discovery of an amazing new technique — radiocarbon dating.

radiochemical dating uses-30

If one knows how much of this radioactive material was present initially in the object (by determining how much of the material has decayed), and one knows the half-life of the material, one can deduce the age of the object.

Climate science required the invention and mastery of many difficult techniques.

He was looking for the carbon that human industry had been emitting by burning fossil fuels, in which all the carbon-14 had long since decayed away.

Comparing the old wood with modern samples, he showed that the fossil carbon could be detected in the modern atmosphere.(5) Through the 1950s and beyond, carbon-14 workers published detailed tables of dates painstakingly derived from samples of a wondrous variety of materials, including charcoal, peat, clamshells, antlers, pine cones, and the stomach contents of an extinct Moa found buried in New Zealand.(6) The measurements were correlated with materials of known dates, such as a well-documented mummy or a log from the roof of an old building (where tree rings gave an accurate count of years).

Their exquisitely sensitive instrumentation was originally developed for studies in entirely different fields including nuclear physics, biomedicine, and detecting fallout from bomb tests.(1) Much of the initial interest in carbon-14 came from archeology, for the isotope could assign dates to Egyptian mummies and the like.

As for still earlier periods, carbon-14 dating excited scientists (including some climate scientists) largely because it might shed light on human evolution — the timing of our development as a species, and how climate changes had affected that.(2) It was especially fascinating to discover that our particular species of humans arose something like 100,000 years ago, no doubt deeply influenced by the ice ages.(3) A few scientists noticed that the techniques might also be helpful for the study of climate itself.

The results were then compared with traditional time sequences derived from glacial deposits, cores of clay from the seabed, and so forth.

One application was a timetable of climate changes for tens of thousands of years back.

Thus the less of it that remained in an object, in proportion to normal carbon, the older the object was.

By 1950, Willard Libby and his group at the University of Chicago had worked out ways to measure this proportion precisely.

Delicate operations were needed to extract a microscopic sample and process it.