The radioactive isotope carbon-14 is created in the upper atmosphere when cosmic-ray particles from outer space strike nitrogen atoms and transform them into radioactive carbon.Some of the carbon-14 might find its way into living creatures.The best way to transfer the exacting techniques was in the heads of the scientists themselves, as they moved to a new job.The prodigious mobilization of science that produced nuclear weapons was so far-reaching that it revolutionized even the study of ancient climates.Nuclear laboratories, awash with funds and prestige, spun off the discovery of an amazing new technique radiocarbon dating.After a creature's death the isotope would slowly decay away over millennia at a fixed rate.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.
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.
Climate science required the invention and mastery of many difficult techniques.
These had pitfalls, which could lead to controversy.
An example of the ingenious technical work and hard-fought debates underlying the main story is the use of radioactive carbon-14 to assign dates to the distant past.
For other examples, see the essays on Temperatures from Fossil Shells and Arakawa's Computation Device.