ly destructive. One pound ofCFCs can capture and annie seventy tmospime—about a century on average—wreaking he while.

    t  sponges. A single CFC molecule is about ten times moreefficient at exacerbating greens tself as a green, cimately prove to be just about t invention of tietury.

    Midgley never kneructiveCFCs er becoming crippled ed a contraption involving a series of motorized pulleys t automaticallyraised or turned angled in tinto action and rangled.

    If you erested in finding out ty of Co be. illard Libby ing radiocarbon dating,alloists to get an accurate reading of to do before. Up to time, t reliable dates back no furt Dynasty in Egypt from about 3000B.C. No one couldconfidently say, for instance, ed or at ime in tted the caves of Lascaux in France.

    Libby’s idea   in 1960. It ion t all living tope of carbon calledcarbon-14,  a measurable rate tant t is, time it takes for o disappear1—of about 5,600 years,so by   a goodfix on t—to a point. After eigive carbon remains, tle to make a reliable measurement, soradiocarbon dating s up to forty thousand or so years old.

    Curiously, just as tecain fla becameapparent. to begin   one of ts of Libby’sformula, knoant,  3 percent. By time, s aken t tate everyone, scientists decided to keep te constant. “tim Flannery notes, “everyrae you read today is given as too young by around 3 percent.” t quite stop t  carbon-14 samples can beeasily contaminated iny scrap of vegetable matter, forinstance, t ed  not