glace polaire profonde

CONT: Si l'on veut mettre en évidence les fluctuations du climat dont les périodes dépassent le siècle, il convient de disposer d'informations débordant largement une telle durée. [...] Aussi les chercheurs ont-ils dû faire appel à des procédés d'investigation indirects qui se sont singulièrement perfectionnés au fil des années, tels que, l'analyse historique des chroniques anciennes, la dendroclimatologie, [...] la méthode du carbone 14 [...], l'analyse isotopique des composants des glaces polaires profondes, l'identification des trajectoires de retombées volcaniques anciennes.
CONT: La glace polaire profonde est au contraire un milieu totalement stérile et quasiment exempt de radio-activité.

CONT: The polar ice sheets are sedimentary deposits that contain records of past precipitation, atmospheric gases and wind blown material that was deposited without water or ice precipitation. Deep polar ice can be collected from these stratigraphic sequences by deep ice coring and used to address many high profile questions about the structure and function of the earth system.
CONT: A group of scientists has identified a subglacial lake in Antarctica that could serve as a testing ground for sterile drilling into deep polar ice. Scientists are eager to examine any bacteria living in subglacial lakes, since the environment is so extreme and the organisms have likely been evolutionarily isolated for millions of years.
OBS: Polar ice consists of sea ice formed from the freezing of sea water, and ice sheets and glaciers formed from the accumulation and compaction of falling snow. Both types of ice extend over vast areas of the polar regions.