NOAA/WDS Paleoclimatology - Northeast Queensland 350 Year Summer Rainfall Reconstructions

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.