North American Ice cover39, orbitally induced solar forcing40, eastern tropical Pacific (ETP - green) and western tropical Pacific (WTP - orange) sea surface temperatures (SST’s)9,10 from foraminifera, ENSO events per century inferred from South American lake sediments41, record of eastern tropical Pacific precipitation inferred from Galapagos Island lake sediment silt content and of ENSO frequency inferred from Galapagos Island lake sediment sand content25, alkenone based reconstruction of eastern North Pacific SST’s from ODP101911 (Fig. 1), Kirman Lake Pinus-Artemisia pollen ratio, LOI and diatom-inferred depth and salinity.
Dry mid-Holocene period indicated with light grey shading, 4.2 ka wet interval indicated by dark grey shading. Medieval Climate Anomaly (MCA) dry interval is indicated with tan shading. Heavier overlay lines represent LOESS (span 0.10) smoothed series.