Identifying Hydro‐Sensitive Coral δ<sup>18</sup>O Records for Improved High‐Resolution Temperature and Salinity Reconstructions
D. M. Thompson, Jessica L. Conroy, Bronwen Konecky, Samantha Stevenson, Kristine L. DeLong, Nicholas P. McKay, Emma V. Reed, Lukas Jonkers, Matthieu Carré
Abstract
Abstract Stable oxygen isotopic ratios in corals (δ 18 O coral ) are commonly utilized to reconstruct climate variability beyond the limit of instrumental observations. These measurements provide constraints on past seawater temperature, due to the thermodynamics of isotopic fractionation, but also past salinity, as both salinity and seawater δ 18 O (δ 18 O sw ) are similarly affected by precipitation/evaporation, advection, and other processes. We use historical observations, isotope‐enabled model simulations, and the PAGES Iso2k database to assess the potential of δ 18 O coral to provide information on past salinity. Using ‘‘pseudocorals’’ to represent δ 18 O coral as a function of observed or simulated temperature and salinity/δ 18 O sw , we find that δ 18 O sw contributes up to 89% of δ 18 O coral variability in the Western Pacific Warm Pool. Although uncertainty in the δ 18 O sw ‐salinity relationship influences the inferred salinity variability, corals from these sites could provide valuable δ 18 O sw reconstructions. Coordinated in situ monitoring of salinity and δ 18 O sw is vital for improving estimates of hydroclimatic change.