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The Research
Coral Paleoclimatology
My main research interest focuses on the reconstruction of high resolution climate records from massive hermatypic coral colonies (Porites sp. and Montastraea sp.). The colonies were collected at various locations in the Pacific and Atlantic Oceans where the variability of stable isotopes (δ18O and δ13C) and trace elements (Sr/Ca, Mg/Ca and others) found in their skeletons are used as proxies of changing oceanographic conditions such as sea surface temperature and salinity.
The coral samples were collected from various locations in the Eastern Pacific (Clipperton Atoll), Western Pacific (Republic of Palau; Republic of Indonesia), South Pacific (Republic of Fiji; Kingdom of Tonga; Rarotonga, Cook Islands), and Southern Caribbean (Bonaire) allowing for the development of regional proxy records to better understand global climate change synchronicity.
One central question in my research is the reproducibility of climate proxies from individual coral colonies of a single region, because the oceanographic and climatic interpretations are only as accurate as the proxy allows. Another important question of my research is the variability of climate over various time-scales ranging from seasonal/annual to inter-annual (patterns of El Niño/La Niña) to decadal oscillations.
I am also concerened with the state of coral reef ecosystems across the Pacific because they are under threat due to ocean acidification from the increasing anthropogenic carbon dioxide in the atmosphere that is taken up by the oceans. This effect has already been shown to impair marine calcifying organisms ability to secrete calcium carbonate skeletons thus hindering climate researchers' ability to accurately interpret climate proxies.
The coral samples were collected from various locations in the Eastern Pacific (Clipperton Atoll), Western Pacific (Republic of Palau; Republic of Indonesia), South Pacific (Republic of Fiji; Kingdom of Tonga; Rarotonga, Cook Islands), and Southern Caribbean (Bonaire) allowing for the development of regional proxy records to better understand global climate change synchronicity.
One central question in my research is the reproducibility of climate proxies from individual coral colonies of a single region, because the oceanographic and climatic interpretations are only as accurate as the proxy allows. Another important question of my research is the variability of climate over various time-scales ranging from seasonal/annual to inter-annual (patterns of El Niño/La Niña) to decadal oscillations.
I am also concerened with the state of coral reef ecosystems across the Pacific because they are under threat due to ocean acidification from the increasing anthropogenic carbon dioxide in the atmosphere that is taken up by the oceans. This effect has already been shown to impair marine calcifying organisms ability to secrete calcium carbonate skeletons thus hindering climate researchers' ability to accurately interpret climate proxies.
Current Research
Caribbean Climate of the Terminal Classic Period
Sub-seasonal climate reconstructions from southern Caribbean corals during the classic Maya civilization collapse of the Terminal Classic Period (~AD 750-1050)
MARUM Research Area: Ocean and Climate (OC)
MARUM Research Area: Ocean and Climate (OC)
- Funding:
MARUM Postdoctoral Fellowship
MARUM Incentive Fund 2011 and 2012 (with Dr. Thomas Felis)
- Collaborators:
Dr. Thomas Felis (MARUM)
Dr. Cyril Giry (MARUM)
Dr. Martin Kölling (MARUM)
Dr. Denis Scholz (Institute for Geosciences, University of Mainz, Germany)
Dr. Klaus-Peter Jochum (Max Planck Institute for Chemistry, Mainz, Germany)
Dr. Sander Scheffers (Southern Cross University, Australia)
Researchers have hypothesized on the many causes of the demise of the Classic Maya civilization during the Terminal Classic Period (TCP; ~AD 750 to 1050) in the lowlands of the Yucatán Peninsula. Explanations ranged from foreign invasion to social turmoil but recent evidence suggests severe climate change such as prolonged dry cycles as the primary influence.
Paleo-records from ocean/lake sediments [Hodell et al., 1995; Haug et al., 2003], stalagmites [Medina-Elizalde et al., 2010; Lachniet et al., 2012; Kennett et al., 2012], dendrochronology [Stahle et al., 2011], and reanalysis studies [Medina-Elizalde and Rohling, 2012] have indicated significant influence of abrupt summer precipitation changes and sustained droughts within the late Holocene coinciding with the time period of Classic Maya civilization collapse. However, seasonal to interannual and decadal variability on the timescale relavant to the Maya civilization remains unclear.
Recently collected sub-modern coral colonies from Bonaire in the Caribbean region that grew during the TCP have been analyzed for Sr/Ca and δ18O at bimonthly resolution as proxies of sea surface temperature (SST) and sea surface salinity (SSS).
Paleo-records from ocean/lake sediments [Hodell et al., 1995; Haug et al., 2003], stalagmites [Medina-Elizalde et al., 2010; Lachniet et al., 2012; Kennett et al., 2012], dendrochronology [Stahle et al., 2011], and reanalysis studies [Medina-Elizalde and Rohling, 2012] have indicated significant influence of abrupt summer precipitation changes and sustained droughts within the late Holocene coinciding with the time period of Classic Maya civilization collapse. However, seasonal to interannual and decadal variability on the timescale relavant to the Maya civilization remains unclear.
Recently collected sub-modern coral colonies from Bonaire in the Caribbean region that grew during the TCP have been analyzed for Sr/Ca and δ18O at bimonthly resolution as proxies of sea surface temperature (SST) and sea surface salinity (SSS).
PAGES Ocean2K
I am currently collaborating with international researchers on a project in the PAGES (Past Global Changes) 2K Network: Ocean2K. In the Ocean2K Working Group, we are attempting to place the modern warming and ocean variability in the context of the last two millennia through climate reconstructions derived from sediment cores and corals. Paleoceanographic evidence have been compiled from high-resolution archives (corals) for synthesis and a global ocean variability synthesis product will be made available soon. Please click on the links above for more information.
Coral-based reconstruction of the Indonesian Throughflow
- Funding:
US National Science Foundation
MARUM Postdoctoral Fellowship
- Collaborators:
Dr. Braddock K. Linsley (Lamont-Doherty Earth Observatory of Columbia University, NY, USA)
Dr. Tim Rixen (ZMT-Leibniz Center for Tropical Marine Ecology, Bremen, Germany)
Dr. Peter B. deMenocal (Lamont-Doherty Earth Observatory of Columbia University, NY, USA)
Dr. Chris Charles (Scripps Insistution of Oceanography, La Jolla, CA, USA)
Recently collected modern coral colonies from the Makassar Strait, Indonesia in the path of the Indonesian Throughflow have been analyzed for Sr/Ca and δ18O at monthly resolution as proxies of sea surface temperature (SST) and sea surface salinity (SSS).