Climatologists have bet heavily on their analysis of cores extracted from the ice sheets of Greenland and Antarctica. Their trace impurities are believed to accurately record the earth's climate over the last several hundred thousand years. The temporal accuracy of this record is based upon the assumption that these impurities have not migrated vertically from where they were deposited. This assumption is now under severe stress with the discovery of anomalous diffusion within ice plus a phase phenomenon called "premelting," both of which result in the transport of the climate-marking impurities far from their original layer of deposition.
A.W. Rempel et al write below (in the jargon of climatologists):
...under conditions that resemble those encountered in the Eemian interglacial ice of central Greenland (from about 125,000 to 115,000 years ago---impurity fluctuations may be separated from ice of the same age by as much as 50 cm. This distance is comparable to the ice thickness of the contested sudden cooling events in the Eemian ice from the GRIP core.
Translation: The accepted picture of the earth's climate history over the last few hundred thousand years may be seriously distorted.
(Rempel, A.W., et al; "Possible Displacement of the Climate Signal in Ancient Ice by Premelting and Anomalous Diffusion," Nature, 411:568, 2001.)
Comment. This discovery could impact the global-warming controversy as well as our model of human activities during the Ice Ages.