About the Cover

Last austral summer, researchers stayed in this field camp near Allan Hills, Antarctica, where they had found bits of multimillion-year-old ice. International teams also aim to drill continuous cores that peer further back in time than ever before; air trapped in old ice provides a unique archive of the ancient atmosphere. In other Antarctic research, scientists are probing Thwaites Glacier with an instrument that swims below it. See page 18 for more on the search for the oldest ice and page 16 for surprises about glacial melting. (Courtesy of Julia Marks Peterson.)