NOAA/WDS Paleoclimatology - R17 Coral Luminescence rainfall reconstruction, PAGES Australasia 2k Version

STUDY NOTES: Uploaded by R. Neukom, data obtained from NOAA Paleo DB.
ABSTRACT SUPPLIED BY ORIGINATOR: Northeast tropical Queensland rainfall is concentrated in the summer half year and characterised by high interannual variability, partly related to El Niño-Southern Oscillation (ENSO) events. This results in highly variable river flows affecting near shore coral reefs of the Great Barrier Reef, Australia. Freshwater flood events are recorded in long-lived, annually-banded massive coral skeletons as luminescent lines. Quantitative measurements of luminescence intensity were made for 20 Porites coral cores from near shore reef sites between 11°-23°S. Seventeen of the coral luminescence series were significantly correlated with an instrumental record of NE Queensland summer rainfall and used to develop seven significantly calibrated and verified rainfall reconstructions based on between 17 (starting 1891) and one (starting 1639) coral series. The longest reconstruction, based on more than one coral, provides insights into NE Queensland rainfall variability from the late 17th century. Comparisons with various independent climate proxies are equivocal - the magnitude and significance of relationships with, for example, a proxy ENSO index vary through time. An extended drier period reconstructed from ~1760s to 1850s is associated with lower interannual rainfall variability. Since the late 19th century average rainfall and its variability have significantly increased with wet and dry extremes becoming more frequent than in earlier centuries. This suggests that a warming global climate maybe associated with more variable tropical Queensland rainfall.