The importance of understanding recent and past climatic changes is crucial to provide the correct perspective in studies aimed to define future global climate evolution. The Southern Ocean and in particular the Ross Sea are crucial areas for this purpose, mostly because they play a key role in controlling the global carbon cycle, as represent, on a whole, one of the largest oceanic ventilation area where intermediate and deep waters are in direct contact with the atmosphere. The record of past environmental changes, and their effects on ocean biogeochemistry, is preserved in marine sediments and can be used to reconstruct the response of the Ross Sea Ice sheet/shelf to natural climate changes during the Holocene. The morphology of the Ross Sea continental shelf is unique with noticeable depth of the shelf break and deepening of the continental shelf towards the coast. Its rugged topography, with troughs and banks transversal to the shelf break, was shaped by glacial erosion, creating different depositional settings. Nine gravity cores were collected in three different basins (Drygalsky, Joides and Pennell Trough) of the Ross Sea. Biogenic silica, organic carbon, magnetic susceptibility and water contents were analysed together with stable isotope (d13C, d15N and d18O) composition to reconstruct the Late Pleistocene-Holocene climatic evolution. Chronologies were established on the basis AMS 14C dates. Sediment cores span in time from last glacial to present. During the transition from MIS 2 to present interglacial, at least two major cooling episodes can be observed. We will discuss the possibility that the first climatic episode can be identified as the Antarctic Cold Reversal event, whereas the more recent one can be attributed to the Younger Dryas cooling event. The latter provides a further evidence of the climatic synchronicity between the Ross Sea area and the Northern hemisphere, as a response to global oceanic circulation of deep waters and their upwelling along the Antarctic continental shelves. An accurate calibrated chronology for the late Pleistocene/Holocene is a key point for discussing high- frequency climatic fluctuations and this is one of the objectives of the PAREO Project (PAleoclimatic REconstructions at High Resolution in Marine Sedimentary Sequences from Polar Oceans) involved in the BIPOMAC
Holocene paleoclimatic reconstruction in shelf basins of the Ross Sea (Antartica)
Ravaioli M;Langone L;Capotondi L;Giglio F;
2006
Abstract
The importance of understanding recent and past climatic changes is crucial to provide the correct perspective in studies aimed to define future global climate evolution. The Southern Ocean and in particular the Ross Sea are crucial areas for this purpose, mostly because they play a key role in controlling the global carbon cycle, as represent, on a whole, one of the largest oceanic ventilation area where intermediate and deep waters are in direct contact with the atmosphere. The record of past environmental changes, and their effects on ocean biogeochemistry, is preserved in marine sediments and can be used to reconstruct the response of the Ross Sea Ice sheet/shelf to natural climate changes during the Holocene. The morphology of the Ross Sea continental shelf is unique with noticeable depth of the shelf break and deepening of the continental shelf towards the coast. Its rugged topography, with troughs and banks transversal to the shelf break, was shaped by glacial erosion, creating different depositional settings. Nine gravity cores were collected in three different basins (Drygalsky, Joides and Pennell Trough) of the Ross Sea. Biogenic silica, organic carbon, magnetic susceptibility and water contents were analysed together with stable isotope (d13C, d15N and d18O) composition to reconstruct the Late Pleistocene-Holocene climatic evolution. Chronologies were established on the basis AMS 14C dates. Sediment cores span in time from last glacial to present. During the transition from MIS 2 to present interglacial, at least two major cooling episodes can be observed. We will discuss the possibility that the first climatic episode can be identified as the Antarctic Cold Reversal event, whereas the more recent one can be attributed to the Younger Dryas cooling event. The latter provides a further evidence of the climatic synchronicity between the Ross Sea area and the Northern hemisphere, as a response to global oceanic circulation of deep waters and their upwelling along the Antarctic continental shelves. An accurate calibrated chronology for the late Pleistocene/Holocene is a key point for discussing high- frequency climatic fluctuations and this is one of the objectives of the PAREO Project (PAleoclimatic REconstructions at High Resolution in Marine Sedimentary Sequences from Polar Oceans) involved in the BIPOMACI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
