Marine Paleoclimate Records

Project Leader: Giuseppe Cortese

This project utilises the climate archives preserved in marine sediment cores to identify the main drivers, mechanisms and patterns of climate change in the southwest Pacific over the last 20 million years. The research has a focus on generating time series of oceanic environmental change over glacial-interglacial cycles, with emphasis on glacial terminations and episodes of past global warmth, such as Marine Isotopes Stages 5 and 11 (often quoted as possible analogues of future climate states), in order to refine understanding of the regional impact of future global warming.

Map of SST anomalies (ºC) for MIS 5e at the investigated sites. Simplified surface currents inferred for MIS 5e are also shown (Abbreviations: SEC = South Equatorial Current, EAC = East Australian Current, TF = Tasman Front, TR = Tasmania Retroflection, SC = Southland Current, WE = Wairarapa Eddy, ACC = Antarctic Circumpolar Current). SST anomalies are color-coded as blue (negative), green (0 to 2oC), red (>2oC).

Map of SST anomalies (ºC) for MIS 5e at the investigated sites.
Simplified surface currents inferred for MIS 5e are also shown (Abbreviations: SEC = South Equatorial Current, EAC = East Australian Current, TF = Tasman Front, TR = Tasmania Retroflection, SC = Southland Current, WE = Wairarapa Eddy, ACC = Antarctic Circumpolar Current). SST anomalies are color-coded as blue (negative), green (0 to 2oC), red (>2oC).

Recent updates and outputs

  • A collaborative study with New Zealand and Australian researchers (Bostock et al. 2012), has shown that sea surface temperatures (SSTs) in the Australian-New Zealand sector of the Southern Ocean were up to 7˚C cooler during the Last Glacial Maximum, ~20,000 years ago. During the ensuing deglaciation, sea-ice retreated and SST increased rapidly. Air temperatures and SSTs reached a maximum in the early Holocene (~ 10,000 years ago), when the Subtropical Front was located at its most southerly position and the Antarctic ice sheets retreated to their modern position. A decline to modern SST and air temperatures followed in the mid to late Holocene.
  • Initial results of a study of Marine Isotope Stage 5e (~120,000 years ago) has identified several similarities between modern ocean changes and conditions recorded in sedimentary archives for this past period of climatic warmth. A stronger circulation in the South Pacific Gyre and an increasing trend in wind stress curl result in a strengthened East Australian Current (EAC), displacing biota southwards along the eastern Australian coast, and bringing warmer waters around Tasmania. The Tasman Front exhibits a decoupled response to this warming, with waters on the western coast of South Island of New Zealand slightly cooling. The Southland Current instead follows the same warming trend as the EAC, thus resulting in warming of surface waters on the Campbell Plateau.
  • Researchers from this project have been awarded ship time on the RV Investigator - the new Australian state-of-the-art marine research vessel. The proposal, led by researchers from Macquarie University, is titled: “Geological and atmospheric characterisation of the Southwest Pacific sector”, and the grant will cover 43 days at sea.

See Outputs and Outcomes for our latest publications.

Team