Changes in wind-driven upwelling during the last three centuries:: Interocean teleconnections

Analysis of sediments from two wind-driven upwelling systems, Guaymas and Cariaco basins, using the alkenone-based U-37(K') paleothermometer yielded high-resolution records of sea surface temperatures (SST) from 1700 to 2000 AD. The trends in the U-37(K') index reveal steady SST increases of 1 to 2 degrees 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.