The White Planet: The Evolution and Future of Our Frozen World

The term cornucopia, attributed by the journal Nature to the Antarctic Vostok ice core drilling, deserves explanation. In the mid-1980s, our knowledge of the great glacial/interglacial cycles that marked the Quaternary essentially rested on the study of marine sediments. Thanks to them the astronomical theory, which stipulates the existence of a connection between the variations in insolation linked to the slow evolution of the Earth’s orbit and those great climatic cycles, had been very widely accepted. In the wake of the article published in Science in 1976 by Jim Hays, John Imbrie, and Nick Shackleton, who established the connection, paleoceanographers put an ambitious program into motion: the Climate/Long Range Investigation Mappings and Predictions Project (CLIMAP) aimed to map the climatic conditions that ruled over all the oceans in the Last Glacial Maximum.¹ The data, published during the 1970s and the beginning of the 1980s, fully reveal how marine sediments have aided in our knowledge of past climates.

Ice core drilling and science in Greenland and Antarctica were still in their infancy at this time. Thanks to high accumulation, ice core drilling at Byrd offered a very great thickness of ice for a detailed study of the last deglaciation, which began around 20,000 years ago, and of the warm period in which we have been living for more than 11,000 years. On the other hand, the ice of the last glacial period proved difficult to date beyond 60,000 years. The situation was rather similar for the two core samplings from Greenland that were available then, those of Camp Century and Dye3, for a simple reason: the oldest ice corresponded to the deep part of the core, the final 150 to 200 meters near the bedrock. The flow of the ice becomes increasingly complex the closer one gets to it, to the point that it is impossible to develop a flow model sufficiently reliable to establish a chronology.

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