Tiwari
Manish
Tiwari
Manish
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ArticleCoral record of younger dryas chronozone warmth on the Great Barrier Reef(American Geophysical Union, 2020-12-11) Brenner, Logan D. ; Linsley, Braddock K. ; Webster, Jody M. ; Potts, Donald C. ; Felis, Thomas ; Gagan, Michael K. ; Inoue, Mayuri ; McGregor, Helen V. ; Suzuki, Atsushi ; Tudhope, Alexander W. ; Esat, Tezer M. ; Thomas, Alexander L. ; Thompson, William G. ; Fallon, Stewart ; Humblet, Marc ; Tiwari, Manish ; Yokoyama, YusukeThe Great Barrier Reef (GBR) is an internationally recognized and widely studied ecosystem, yet little is known about its sea surface temperature (SST) evolution since the Last Glacial Maximum (LGM) (~20 kyr BP). Here, we present the first paleo‐application of Isopora coral‐derived SST calibrations to a suite of 25 previously published fossil Isopora from the central GBR spanning ~25–11 kyr BP. The resultant multicoral Sr/Ca‐ and δ18O‐derived SST anomaly (SSTA) histories are placed within the context of published relative sea level, reef sequence, and coralgal reef assemblage evolution. Our new calculations indicate SSTs were cooler on average by ~5–5.5°C at Noggin Pass (~17°S) and ~7–8°C at Hydrographer's Passage (~20°S) (Sr/Ca‐derived) during the LGM, in line with previous estimates (Felis et al., 2014, https://doi.org/10.1038/ncomms5102). We focus on contextualizing the Younger Dryas Chronozone (YDC, ~12.9–11.7 kyr BP), whose Southern Hemisphere expression, in particular in Australia, is elusive and poorly constrained. Our record does not indicate cooling during the YDC with near‐modern temperatures reached during this interval on the GBR, supporting an asymmetric hemispheric presentation of this climate event. Building on a previous study (Felis et al., 2014, https://doi.org10.1038/ncomms5102), these fossil Isopora SSTA data from the GBR provide new insights into the deglacial reef response, with near‐modern warming during the YDC, since the LGM.
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ArticleIntensification of the meridional temperature gradient in the Great Barrier Reef following the Last Glacial Maximum(Nature Publishing Group, 2014-06-17) Felis, Thomas ; McGregor, Helen V. ; Linsley, Braddock K. ; Tudhope, Alexander W. ; Gagan, Michael K. ; Suzuki, Atsushi ; Inoue, Mayuri ; Thomas, Alexander L. ; Esat, Tezer M. ; Thompson, William G. ; Tiwari, Manish ; Potts, Donald C. ; Mudelsee, Manfred ; Yokoyama, Yusuke ; Webster, Jody M.Tropical south-western Pacific temperatures are of vital importance to the Great Barrier Reef (GBR), but the role of sea surface temperatures (SSTs) in the growth of the GBR since the Last Glacial Maximum remains largely unknown. Here we present records of Sr/Ca and δ18O for Last Glacial Maximum and deglacial corals that show a considerably steeper meridional SST gradient than the present day in the central GBR. We find a 1–2 °C larger temperature decrease between 17° and 20°S about 20,000 to 13,000 years ago. The result is best explained by the northward expansion of cooler subtropical waters due to a weakening of the South Pacific gyre and East Australian Current. Our findings indicate that the GBR experienced substantial meridional temperature change during the last deglaciation, and serve to explain anomalous deglacial drying of northeastern Australia. Overall, the GBR developed through significant SST change and may be more resilient than previously thought.