Improved Extended Reconstruction of SST (1854–1997)

TLDR

The study develops an improved sea‑surface temperature reconstruction covering 1854–1997. The reconstruction incorporates sea‑ice concentration data for high‑latitude SST, applies a modified bias correction for 1939–41, and includes an improved error estimate. The new reconstruction resolves more variance in key ocean basins, shows larger uncertainty in the 19th century and wartime periods, but yields a near‑global average SST consistent with the previous version, with 95 % confidence intervals of 0.4 °C or more in the 19th century, ~0.2 °C in the early 20th century, and ≤0.1 °C after 1950.

Abstract

An improved SST reconstruction for the 1854–1997 period is developed. Compared to the version 1 analysis, in the western tropical Pacific, the tropical Atlantic, and Indian Oceans, more variance is resolved in the new analysis. This improved analysis also uses sea ice concentrations to improve the high-latitude SST analysis and a modified historical bias correction for the 1939–41 period. In addition, the new analysis includes an improved error estimate. Analysis uncertainty is largest in the nineteenth century and during the two world wars due to sparse sampling. The near-global average SST in the new analysis is consistent with the version 1 reconstruction. The 95% confidence uncertainty for the near-global average is 0.4°C or more in the nineteenth century, near 0.2°C for the first half of the twentieth century, and 0.1°C or less after 1950.