Recent climate ‘predictions’ have stretched both forward and backward in time. Leona Marshall Libby of the University of California at Los Angeles has tracked back nature's records, in some cases to 100 A.D., using painstaking chemical analysis to decipher the past. Libby and Louis J. Pandolfi investigated five separate indicators to identify the periods of former climate cycles and report surprising agreement among all of them. The two scientists and their colleagues have related measurements of sediment cores from the bottom of the Santa Barbara Channel, tree rings from cedars in Japan and from giant sequoia in King's Canyon National Park, cores from the Greenland ice cap, and annual variations in the catch of blue crabs in Chesapeake Bay.