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SEMINAR: CWR Presents

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Today's date is Friday, March 29, 2024
CWR Presents : Madagascar and Great Barrier Reef corals reveal a multidecadal signature of rainfall and river runoff . Other events...
Pacific Ocean sea surface temperatures (SST) influence rainfall variability on multidecadal and interdecadal timescales in concert with the Pacific Decadal Oscillation (PDO) and Interdecadal Pacific Oscillation (IPO). Rainfall variations in locations such Australia and North America are therefore linked to phase changes in the PDO.

As instrumental records of rainfall are too short and too sparse to confidently assess multidecadal climatic teleconnections, here we present four coral climate archives from Madagascar spanning up to the past 300 years (1708 – 2008) and six corals from the Keppel Islands (southern Great Barrier Reef (GBR), Fitzroy River catchment, 1920-2011) to assess such decadal variability.

Using spectral luminescence scanning to reconstruct past changes in river runoff, we identify significant multidecadal and interdecadal frequencies in the coral record. For the 20th century, we decouple human deforestation effects in Madagascar from rainfall induced soil erosion by pairing luminescence with coral geochemistry to isolate decadal and multi-decadal climate variability.

We find that our Madagascar coral record is coherent with Asian-based PDO reconstructions pre- and post 1920. This multidecadal relationship with the Asian PDO records, points to teleconnection mechanisms that affects Madagascar rainfall/runoff, most likely triggered by multidecadal changes in North Pacific SST, influencing the Asian Monsoon circulation.

Positive PDO phases are associated with increased Indian Ocean temperatures and runoff/rainfall in eastern Madagascar, while precipitation in southern Africa and eastern Australia declines. We contrasted our findings with a record from the Keppels islands in the GBR to reveal its sensitivity to PDO forcing. We find that river runoff entering the southern GBR is largely driven by the PDO. We conclude that multidecadal rainfall variability in Madagascar and Eastern Australia needs to be taken into account when considering water resource management under a future warming climate.

Short Bio:

Jens did his PhD in the year 2000 at the IFM-GEOMAR institute in Kiel, Germany. He worked at the Free University in Amsterdam (Netherlands) and the Royal Netherlands Institute for Sea Research between 2003-2011.

Since June 2011, Jens is Assistant Professor at the UWA Oceans Institute. His research involves the geochemical study of marine biological archives (massive corals) from the Indian Ocean as recorders of environmental and climate change over the past 300 years and during the Holocene. In most cases, he worked on western Indian Ocean coral records. As part of his appointment at UWA Oceans Institute, Jens also works on Australian coral records. This work is motivated by the need to produce reliable, long-term observations of sea surface temperature, ocean currents and the hydrological cycle over the tropical/subtropical oceans.

PS* This seminar is free and open to the public & no RSVP required.

****All Welcome***
Speaker(s) Jens Zinke, Research Assistant Professor, Earth and Environment and Australian Institute of Marine Science, UWA Oceans Institute & University of Western Australia
Location Blakers Lecture Room, Ground Floor, Mathematics Building, The University of Western Australia
Contact Askale Abebe <[email protected]> : 6488 7565
URL http://www.dlist-asclme.org/group/coral-reefs-and-global-change
Start Wed, 19 Jun 2013 16:00
End Wed, 19 Jun 2013 17:00
Submitted by Askale Abebe <[email protected]>
Last Updated Thu, 29 Aug 2013 16:03
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