Evidence of reduced mid‐Holocene ENSO variance on the Great Barrier Reef, Australia

• Published in: Paleoceanography 2016-09, Vol.31 (9), p.1248-1260
• Main Authors: Leonard, N. D., Welsh, K. J., Lough, J. M., Feng, Y.‐x., Pandolfi, J. M., Clark, T. R., Zhao, J.‐x.
• Format: Article
• Language: English
• Subjects: Anthropogenic factors; Barrier reefs; Climate; Climate change; Climate models; Climate variability; Climatic extremes; coral luminescence; Coral reefs; Corals; Dynamics; El Nino; El Nino phenomena; El Nino-Southern Oscillation event; ENSO; Fossils; Geology; Global warming; Great Barrier Reef; Growth; Holocene; Human influences; Lines; Luminescence; Management; Methods; mid‐Holocene; Modelling; Ocean currents; paleoclimate; Porites; Pressure; Records; Sea surface; Sea surface temperature; Southern Oscillation; Strength; Surface temperature; Transformations (mathematics); Variability; Variance; wavelet; Wavelet transforms
• ISSN: 0883-8305; 2572-4517; 1944-9186; 2572-4525
• DOI: 10.1002/2016PA002967

Globally, coral reefs are under increasing pressure both through direct anthropogenic influence and increases in climate extremes. Understanding past climate dynamics that negatively affected coral reef growth is imperative for both improving management strategies and for modeling coral reef responses to a changing climate. The El Niño–Southern Oscillation (ENSO) is the primary source of climate variability at interannual timescales on the Great Barrier Reef (GBR), northeastern Australia. Applying continuous wavelet transforms to visually assessed coral luminescence intensity in massive Porites corals from the central GBR we demonstrate that these records reliably reproduce ENSO variance patterns for the period 1880–1985. We then applied this method to three subfossil corals from the same reef to reconstruct ENSO variance from ~5200 to 4300 years before present (yBP). We show that ENSO events were less extreme and less frequent after ~5200 yBP on the GBR compared to modern records. Growth characteristics of the corals are consistent with cooler sea surface temperatures (SSTs) between 5200 and 4300 yBP compared to both the millennia prior (~6000 yBP) and modern records. Understanding ENSO dynamics in response to SST variability at geological timescales will be important for improving predictions of future ENSO response to a rapidly warming climate. Key Points Continuous wavelet transforms of coral luminescent lines successfully reconstruct ENSO variance on the Great Barrier Reef Fossil coral luminescent index assessment indicates reduced frequency and strength of ENSO in the mid‐Holocene Fossil coral linear extension rates suggest either lower sea surface temperatures or more oligotrophic conditions in the mid‐Holocene