A northern Australian coral record of seasonal rainfall and terrestrial runoff (1775-1986)
Abstract
Northern Australia is a climatically dynamic region influenced by both the El Niño-Southern Oscillation (ENSO) and the Australian monsoon. However, this region is largely devoid of long climate records with sub-annual resolution. Understanding long-term climate variations is essential to assess how the storm-prone coasts and rainfall-reliant rangelands of northern Australia have been impacted in the past and may be in the future. In this study, we present a continuous multicentury (1775-1986) coral reconstruction of rainfall and hydroclimate in northern Australia, developed from a Porites spp. coral core collected off the coast of Darwin, Northern Territory, Australia. We combined Ba/Ca measurements with luminescence data as tracers of terrestrial erosion and river discharge respectively. Our results show a strong seasonal cycle in Ba/Ca linked to wet austral summers driven by the Australian monsoon. The Ba/Ca record is corroborated by oxygen isotope data from the same coral and indices of regional river discharge and rainfall. Consistently high levels of Ba measured throughout the record further attest to the importance of river influence on this coral. Our record also shows changes in variability and the baseline level of Ba in coastal waters through time, which may be driven in part by historical land-use change, such as damming or agricultural practices. We will additionally use these records to examine decadal to centennial-scale variability in monsoonal precipitation and regional ENSO signals.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFMPP31A1257P
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSES;
- 3344 Paleoclimatology;
- ATMOSPHERIC PROCESSES;
- 1620 Climate dynamics;
- GLOBAL CHANGE;
- 4928 Global climate models;
- PALEOCEANOGRAPHY