Multisite Record of Climate Change from Indian Ocean Corals

Abstract

Coral records from coastal East Africa spanning 2° to 7°S (Kiwayu, Malindi, Watamu, Mombasa, Kisite, and Mafia) demonstrate that isotopic tracers preserved within coral aragonite accurately record intraseasonal to interannual changes in sea surface temperature. The strong seasonal signal observed at all six sites most likely reflects sea surface temperature variability forced by ocean circulation and reversals in wind direction associated with the Indo-African Monsoon. Strong southwesterly winds during the Southwest Monsoon initiate evaporative cooling and mixing, resulting in a sea surface temperature minimum in the late boreal summer. Coral δ180 values are higher during this period. Reproducibility in the coral δ180 signal between sites indicates that an individual coral isotope records from the coast of East Africa can be used to reconstruct regional climatic conditions. We present the first multisite analysis of sea surface temperature variability along the East African coast as recorded in the isotopic composition of reef corals.