DOI: 10.25921/0qp7-vy63
title: NOAA/WDS Paleoclimatology - Fanning and Palmyra Island Oxygen Isotope and Nino3.4 Reconstructions from 1863-2016 CE

description: Accurate estimation of central tropical Pacific (CTP) climate variability on interannual to centennial timescales is required for robust projections of future global climate trends. Here we outline an approach that blends instrumental and coral proxy observations to yield a continuous, monthly- resolved record of climate evolution in the CTP spanning the past 160 years. We concatenate coral oxygen isotope (δ18O) records from multiple living and fossil corals collected from Fanning Island (4°N, 160°W) and Palmyra Island (5°N; 162°W) located in the heart of the El Niño-Southern Oscillation. We use the Regularized Expectation Maximization (RegEM) method to impute missing data across short gaps of 5 to 23 years within and beyond individual coral records. The resulting monthly-resolved Fanning/Palmyra Island climate record spans continuously from 1863 to 2016 and provides an example of how extended time series can be built from shorter coral segments. The extended record highlights the strong trend toward warmer and wetter mean conditions in late 20th century, in agreement with the majority of climate model hindcast simulations. The continuous reconstruction also enables a direct comparison of four exceptionally strong El Niño events (1877-78, 1940-41, and 1997-8 and 2015-6). Three of these very strong El Niño events in the central tropical Pacific featured a precursor warm event in the prior year, and that may have favored the development of a strong El Niño event.
description: This study has data from Fanning and Palmyra Islands. The data from Fanning Island (3.9N, 159W) are oxygen isotopic measurements from fossil and living corals. The fossil corals (F4 and F5) were dated using U/Th chemistry. The sequences range in age from 1863 to 2005 and are presented at monthly resolution. We include the full Fanning reconstruction used in the FPrecon reconstruction as the d18O_FPrecon timeseries, and the three constituent subcomponents, the Fanning F5 record (1863-1888), and the raw and scaled Fanning F4 record (1907-1944), and the modern Fanning record (1949-2005, as used in Cobb et al. 2013). Our analysis indicates that the d18O_scaled timeseries is the most appropriate for reconstructing larger scale climate variability. For more information on the decision to scale the Fanning F4 record, please see the manuscript and associated supplementary materials. The data from Palmyra Island are oxygen isotopic measurements from living, modern corals. We include the Palmyra composite used in this study as the d18O_FPrecon time series, as well the two constituent subcomponents, the Palmyra RT10 record (1995-2016), and the Cobb et al. 2001 Palmyra record (1886-1998). This study also contains the reconstructed indices from the applying RegEM algorithm to central tropical Pacific coral and (unless otherwise noted) instrumental archives. See the paper and the Supplementary Information of the Paleoceanography and Paleoclimatology paper for additional information on the sensitivity of the reconstructions to input data and methodology.