INVESTIGATING SUBTROPICAL PACIFIC MULTIDECADAL VARIABILITY: A 500-YEAR HISTORY OF OCEAN SURFACE TEMPERATURE AND PRODUCTIVITY FROM BAJA CALIFORNIA, MEXICO

Natural climate variability can effect abrupt swings in climate state with dramatic biologic and economic consequences. Much short-periodicity (years to decades) variability can be simplified to a characteristic few climate modes, although the strength of these modes varies regionally. Major questions about these modes include their stationarity in frequency and amplitude over time and the possibility that anthropogenic climate change has altered their behavior in comparison to natural variability. To test these questions, we must identify and analyze suitable climate archives in regions where modes of interest dominate modern climate variability. The region of Baja California, Mexico is one such documented hotspot of teleconnection to the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). We present here a high-resolution 500-year history of alkenone-derived SST and productivity from laminated box and Kasten sediment cores at Site PCM 00-78 (25.18N, 112.66W) in the subtropical eastern Pacific at a depth of 540 meters. Our ~2 yr sampling interval partially captures ENSO variations and fully resolves decadal and coarser-scale variability. Over the historical period, our record displays good coherence with the instrumental record and regional climate records. Most pronouncedly, both reconstructed SST and productivity correspond strongly to ENSO and PDO indices. Presuming a steady relationship throughout time, this record is the longest continuous marine reconstruction of ENSO and PDO from the subtropical eastern Pacific to our knowledge. Our data thus serve as a robust high-resolution companion marine record to existing terrestrial Baja reconstructions of centennial climate from tree rings.