A comparison between multi-proxy and historical data of drift-ice conditions on the East Greenland shelf

The reduction in sea ice along the SE Greenland coast during the last century has severely impacted ice-rafting to this area. In order to reconstruct ice-rafting and oceanographic conditions in the area of Denmark Strait during the last ~150 years, we conducted a multiproxy study on three short (20 cm) sediment cores from outer Kangerdlugssuaq Trough (~300 m water depth). The proxy-based data obtained have been compared with historical and instrumental data to gain a better understanding of the ice sheet-ocean interactions in the area. A robust chronology has been developed based on 210Pb and 137Cs measurements on core PO175GKC#9 (~66.2°N, 32°W) and expanded to the two adjacent cores based on correlations between calcite weight percent records. Our proxy records include sea-ice and phytoplankton biomarkers, and a variety of mineralogical determinations based on the <2 mm sediment fraction, including identification with quantitative x-ray diffraction, ice-rafted debris counts on the 63-150 µm sand fraction, and source identifications based on the composition of Fe oxides in the 45-250 µm fraction. A multivariate statistical analysis indicated significant correlations between our proxy records and historical data, especially with the mean annual temperature data from Stykkishólmur (Iceland) and the storis index (historical observations of sea-ice export via the East Greenland Current). In particular, the biological proxies (calcite weight percent, IP25, and total organic carbon %) showed significant linkage with the storis index. Our records show two distinct intervals in the recent history of the SE Greenland coast. The first of these (ad 1850-1910) shows predominantly perennial sea-ice conditions in the area, while the second (ad 1910-1990) shows more seasonally open water conditions.

Results of modelled Arctic river discharge trends since 7 ka BP

The Arctic hydrological cycle throughout the Holocene is analyzed based on the results of transient simulations with the coupled atmosphere-ocean circulation model ECHO-G. The results suggest a ~ 2 % increase of mid-Holocene to preindustrial Arctic river discharges for the Eurasian continent. However, rivers of the North America Arctic realm show a moderate runoff decline of approximately 4 to 5 % for the same period. The total river discharge into the Arctic Ocean has remained at an approximately constant preindustrial level since the mid Holocene. The positive discharge trend within Eurasia is caused by a more rapid decrease in local net evaporation compared to a smaller decline in advected moisture and hence precipitation. This effect is neither recognized within the North American Arctic domain nor in the far eastern part of the Eurasian Arctic realm. A detailed comparison of these model findings with a variety of proxy studies is conducted. The collected proxy records show trends of continental surface temperatures and precipitation rates that are consistent with the simulations. A continuation of the transient Holocene runs for the 19th and 20th century with increased greenhouse gases indicates an increase of the total river influx into the Arctic Ocean of up to 7.6 %. The Eurasian river discharges increase by 7.5 %, the North American discharges by up to 8.4 %. The most rapid increases have been detected since the beginning of the 20th century. These results are corroborated by the observed rising of Arctic river discharges during the last century which is attributed to anthropogenic warming. The acceleration of the Arctic hydrological cycle in the 20th century is without precedence in the Holocene.

Orientalismo en la Argentina: un análisis de las letras argentinas

El informe realizado con motivo del Seminario: Orientalismo en la literatura argentina (s. XIX y XX) a cargo del Dr. Axel Gasquet realizado el 14 y 15 de agosto del 2007 en la Facultad de Filosofía y Letras de la UNcuyo. Axel Gasquet (Buenos Aires, 1966) es profesor titular de literatura en la Universidad Blaise Pascal de Clermont-Ferrand, Francia. Estudió en la UBA y en la EHESS de París. Doctor en Letras por la Universidad de París X-Nanterre. autor del libro"Oriente al sur .El orientalismo literario argentino de Esteban Echeverría a Rodolfo Arlt " El mundo oriental produjo desde siempre una enorme fascinación en los intelectuales y artistas europeos y americanos. Su lejanía y su alteridad inspiraron la creación de imaginarios variados que alternaban entre la construcción negativa fundada en el carácter despótico de sus naciones, distante del racionalismo liberal de raíz eurocentrista, y la admiración por su historia y sus culturas milenarias. La literatura recolectó estas representaciones con fines estéticos y políticos. Desde una apropiación tanto empírica –a través de viajes propios–, como libresca –mediante la lectura de crónicas ajenas–, la primera generación de escritores argentinos incluyó en su producción literaria diversas visiones de Oriente. Éstas, en cierta medida, universalizaron la dicotomía civilización-barbarie adaptando los estereotipos negativos de la extranjería oriental a las fronteras pampeanas. Con el tiempo las imágenes del mundo oriental fueron despojándose de esta carga de significación geopolítica y pasaron a integrar las ficciones literarias como un elemento de gran potencial estético. El seminario pone en diálogo los diferentes modos de representación e inclusión del Oriente en la literatura argentina a lo largo de diferentes épocas y a través de la lente de diversos autores, algunos de ellos de presencia permanente en las letras nacionales, como Echeverría, Alberdi, Sarmiento, Mansilla, Lugones y Arlt, y otros menos frecuentados por el público y la crítica como Pastor Obligado y Max Rohde.

De la methexis a la alienación : o el reverso de la libertad

El artículo realiza una aproximación a la problemática de un “lugar" filosófico de la libertad y de su génesis. A partir de allí se realiza un recorrido por cuatro autores (Hegel, Marx, Lukács, Honneth) donde se presenta la relación entre libertad y alienación. Este análisis se centra en tres tipos de relación donde se manifiesta el fenómeno de la libertad: relación de sí-consigo, con los otros y con el mundo.

Sediment total reflectance measurements from the Cariaco Basin (MD03-2621) and northeastern Arabian Sea (SO130-289KL)

During the last glacial period, the North Atlantic region experienced pronounced, millennial-scale alternations between cold, stadial conditions and milder interstadial conditions-commonly referred to as Dansgaard-Oeschger oscillations-as well as periods of massive iceberg discharge known as Heinrich events. Changes in Northern Hemisphere temperature, as recorded in Greenland, are thought to have affected the location of the Atlantic intertropical convergence zone and the strength of the Indian summer monsoon. Here we use high-resolution records of sediment colour-a measure of terrigenous versus biogenic content-from the Cariaco Basin off the coast of Venezuela and the Arabian Sea to assess teleconnections with the North Atlantic climate system during the last glacial period. The Cariaco record indicates that the intertropical convergence zone migrated seasonally over the site during mild stadial conditions, but was permanently displaced south of the basin during peak stadials and Heinrich events. In the Arabian Sea, we find evidence of a weak Indian summer monsoon during the stadial events. The tropical records show a more variable response to North Atlantic cooling than the Greenland temperature records. We therefore suggest that Greenland climate is especially sensitive to variations in the North Atlantic system-in particular sea-ice extent-whereas the intertropical convergence zone and Indian monsoon system respond primarily to variations in mean Northern Hemisphere temperature.