NOAA/WDS Paleoclimatology - Guaymas and Cariaco Basin 300 Year Alkenone SST Reconstructions

Analysis of sediments from two wind-driven upwelling systems, Guaymas and Cariaco basins, using the alkenone-based Uk'37 paleothermometer yielded high-resolution records of sea surface temperatures (SST) from 1700 to 2000 AD. The trends in the UK'37 index reveal steady SST increases of 1 to 2°C at both sites since the end of the Little Ice Age. Higher-frequency changes in SST indicate a decoupling in the relative intensity of wind-driven upwelling at the two sites. Periods of enhanced upwelling in Guaymas correspond to periods of decreased upwelling in Cariaco (and vice versa). We propose that these contrasts reflect regional differences in the upwelling response of upwelling to changes in the positioning of the Inter-Tropical Convergence Zone (ITCZ) and the Subtropical High (SH) under current climate conditions.