EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

118-year hydroclimate reconstruction from Christmas Island (Indian Ocean); an extended record of variability in the Indonesian Throughflow

Jessica A. Hargreaves1,2, Nerilie Abram1,2, and Jennie Mallela1,3
Jessica A. Hargreaves et al.
  • 1Australian National University, College of Science, Research School of Earth Sciences, Canberra, Australia (
  • 2ARC Centre of Excellence for Climate Extremes, Australia
  • 3Australian National University, College of Science, Research School of Biology, Canberra, Australia

Future climate trends indicate that changes in temperature and precipitation are likely to influence global supply chains, agricultural productivity, water security, health and well-being; particularly in densely populated nations across the southeast Indian Ocean region. The Indonesian Throughflow is an ocean current that transports low-latitude, warm and relatively fresh water from the western Pacific into the eastern Indian Ocean. It is thought that variability and changes in the Indonesian Throughflow have significant impacts on the climate and oceanography of the Indo-Pacific region. The short coverage of observational records makes assessments of hydrological changes across the region challenging on longer timescales, with changes before the 1970s being particularly unreliable. An extended record of Indonesian Throughflow variability needs to be established to contextualise changes and improve model projections of future variability.

Christmas Island, located in the southeast Indian Ocean (not to be confused with the Pacific Ocean Kiritimati Island), is located along an outflow of the Indonesian Throughflow. This Island is an ideal location to develop new palaeo-reconstructions of sea surface temperature and hydroclimate, extending our understanding of Indonesian Throughflow variability. Here we present a newly developed coral palaeoclimate reconstruction for Christmas Island, covering the last 118 years at approximately monthly-fortnightly resolution. Corals are sensitive recorders of critical environmental variables, including sea surface temperature and hydroclimate through the analysis of paired stable oxygen isotopes (δ18O) and trace element (Sr/Ca) ratios. This reconstruction consists of a composite of four newly developed coral records and one previously published record and provides a newly developed δ18Osw variability record for the region. The newly developed δ18Osw coral reconstruction correlates strongly with salinity variability, however, presents a weak relationship to in-situ precipitation, indicating that coral hydroclimate reconstructions from Christmas Island likely isolate salinity variability associated with changes in the strength of the Indonesian Throughflow. This relationship highlights the importance that ocean advection plays on δ18Osw variability at this site. Comparisons to both observational records of the Indonesian throughflow, and previously published coral δ18Osw records from the Ombai Strait (Timor), a major outflow passage, reveal strong relationships to variability at Christmas Island. The Christmas Island reconstruction provides a unique opportunity to extend current knowledge of the Indonesian Throughflow beyond the observational record. This Christmas Island record also provides an opportunity to evaluate the impact that interannual to multidecadal variability has on the climate across the southeast tropical Indian Ocean.

How to cite: Hargreaves, J. A., Abram, N., and Mallela, J.: 118-year hydroclimate reconstruction from Christmas Island (Indian Ocean); an extended record of variability in the Indonesian Throughflow, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-11965,, 2023.

Supplementary materials

Supplementary material file