La banquise Antarctique joue un rôle important sur les flux de chaleur et les échanges de gaz à l'interface océan-atmosphère, sur la circulation océanique globale, sur l'albédo et la productivité primaire de l'Océan Austral. Cependant, du fait de son éloignement et d'un climat extrême, cette région reste à ce jour encore peu étudiés, et représente un verrou pour les modèles prédictifs du climat. De plus, de récentes observations ont montré que le continent Antarctique présente des tendances régionales, dont les causes et les mécanismes sont encore mal compris. Les reconstructions paléoclimatiques de températures tendent à montrer que ces disparités régionales ont également caractérisé la période Holocène. L'Holocène tardif représente la période sur laquelle le réchauffement récent se produit et est également caractérisée par des variations climatiques rapides généralement de plus faibles amplitudes. Afin de mieux évaluer ces changements, l'étude fine des conditions environnementales passées en Antarctique au cours de l'Holocène tardif est essentielle afin d'isoler la part de variabilité climatique naturelle de la part anthropique. Bien qu'un vaste réseau de carottes de glace en Antarctique constitue une base d'informations robuste sur la variabilité atmosphérique passée dans l'Hémisphère Sud, l'étude des conditions paléocéanographiques est contrainte dans la région par le nombre limité d'enregistrements sédimentaires marins,et qui de plus, tendent à être de faible résolution, trop courts ou discontinus. Notre étude porte sur la zone marginale du plateau de la Terre Adélie-Georges V en Antarctique de l'Est, qui a reçu peu d'attention jusqu'à présent, malgré la présence de séquences sédimentaires très épaisses et laminées, permettant la reconstruction fine des variations climatiques passées. Nos travaux ont été réalisés à partir de plusieurs enregistrements sédimentaires marins, couvrant la période instrumentale et jusqu'aux deux derniers millénaires. Nos résultats montrent que les assemblages de diatomées, les biomarqueurs spécifiques des diatomées, ainsi que de la géochimie élémentaire du sédiment traduisent efficacement des variations océanographiques et climatiques locales et aussi régionales à l'échelle interannuelle à centennale. La dynamique couplée océan-atmosphère en lien avec les modes climatiques principaux de l'Hémisphère Sud, ainsi que la dynamique glaciaire constituent les mécanismes de forçage majeurs des changements du couvert de banquise au court de l'Holocène tardif. / Antarctic sea ice has large impacts on the heat and gas transfers between the ocean andthe atmosphere, on the global oceanic circulation, on the Earth albedo and on theprimary productivity of the Southern Ocean. However, because of its remote and icecoveredlocation, the climate of the Antarctic continent and of the Southern Ocean isstill poorly studied and constitutes a challenge for climate model predictions. Recentobservations highlighted opposite patterns of climate variability between Western andEastern Antarctica, but poorly resolved the mechanisms and forcing involved.Reconstructions of temperature signals indicate that regional disparities have persistedover the Holocene period. The Late Holocene period includes the recent climate change(so-called modern global warming) as well as preceding rapid climate variabilitiesthough of lower amplitude. Achieving paleoenvironmental reconstructions in theAntarctic region at high temporal resolution over this period therefore offers theopportunity to improve the understanding of climate changes in response to bothnatural and anthropogenic forcing. While paleoenvironmental records obtained from icecores provide robust information on the past atmospheric conditions over Antarctica,the paleoceanography of the nearby ocean is constrained by a limited set of rather lowresolution, discontinuous records from sediment cores. Our study focuses on themarginal zone of the Adélie-Georges V Land, East Antarctica, a region which has beenpoorly studied so far, despite the presence of thick and laminated sedimentary depositsthat allow accurate and high resolution paleoclimate reconstructions. Our work is basedon several marine sedimentary records, made of diatom oozes and covering theinstrumental period to the last 2,000 years. Our results show that diatom assemblages,diatom specific biomarkers (HBI) and elemental geochemistry in the sedimenteffectively testify of local but also regional oceanographic and climatic variations atdecadal to centennial scales. Coupled atmospheric and oceanic dynamics linked to majorclimate modes of the Southern Hemisphere, along with glacial dynamics constitutemajor forcing mechanisms of ice covered changes during the late Holocene.

This study is a two-phase examination of the desegregation of the 16-campus University of North Carolina system. The first phase involved obtaining and analyzing copies of letters, books, journal articles, newspaper articles and annual reports concerning the court-mandated desegregation plan and its implementation and voluntary continuation after the mandate was rescinded. Reports of black and white student enrollment in historically black institutions (HBIs) and historically white institutions (HWIs) were analyzed for the years 1980, 1988, and 1999. The study found that very substantial increases in minority enrollments occurred in all HBIs and HWIs between 1980 and 1988 and, there were further increases from 1988 to 1999. In absolute numbers, white student enrollments in HBIs increased from 1,801 in 1980 to 3,009 in 1988 (for an increase of 67.1%) and to 3,421 in 1999 (which represented a 13.7% increase from 1988 and a 90.0% increase from 1980). black students in HWIs increased from 7,481 in 1980 to 10,186 in 1988 ( 36.0% increase) and to 14,489 in 1999 ( an increase of 42.2% from 1988 and 87.7% from 1980). black employment in HWIs in faculty and executive/administrative positions increased even more dramatically over the same period. black faculty members in HWIs increased from 138 in 1980 to 206 in 1988 to 310 in 1999, for a total increase of 124.6%. black executive/administrative employment in HWIs rose from 43 in 1980 to 76 in 1988 to 139 in 1999, for a 19-year increase of 223.2%. The second phase of this study involved interviewing the former president and other top-level University of North Carolina system administrators and other principal actors in desegregation planning, implementation and evaluation in the 1970s and 1980s. A second round of interviews was conducted with selected chancellors and directors of admissions in several HBIs and HWIs. The conclusions based upon the responses of both the former and current administrators are that the greatest impediments to increasing black enrollment on HWI campuses were geographic locations of the institutions and the greatest obstacles to increasing black faculty members in HWIs were geographic locations and the lack of new black Ph.D. graduates.