Project overview
There is increasing focus on the need to characterise natural climate variability to identify the relative contributions of natural and anthropogenic forcing. Instrumental records from the last century have demonstrated the significance of interannual scale climate variability, such as El Niño-Southern Oscillation (ENSO), which has a typical recurrence time of 3 to 8 year. Geological records show longer climate fluctuations on centennial to millennial time scales. understanding the interaction between long term and short term climate change is essential for better prediction of future climate change and its socio-economic impact on human societies. Recent climate research indicates that rapid climate fluctuations, like ENSO, may change in frequency and intensity when global climate changes; or inversely, that ENSO-style fluctuations accumulate and trigger long term climate change. To place recent climatic change in the context of such natural cycles it is necessary to produce records of interannual variability over sufficiently long time periods, to characterise the interaction between climate fluctuations at all time scales, from decadal to millennial. Marine laminated sediments are one of the few archives that provide the resolution necessary to address (sub)decadal scales of ocean-climate variability. With RV Marion Dufresne (MD) cruise we retrieved a record length (65 m) giant piston core from the Guaymas Basin (Gulf of California) in the Eastern Pacific Ocean. Much of the sediment in this core is annually laminated (varied), offering the high resolution needed to reconstruct the history of ENSO in relation to millennial scale climate variability for the past ~40,000 yr (last glacial to modern). With this material we aim to address how millennial scale climate change was propagated to/in the eastern subtropical Pacific, by testing if different aspects of climate changed simultaneously (precipitation/river runoff, regional upwelling and wind strength, subsurface water circulation from the North Pacific and from the tropical Pacific). The annual resolution possible in this core will allow us to test if, and how, ENSO changes when global climate changed from cold (glacial) to warm (modern). To date, reconstructions of the wider Pacific climate system to understand the history of ENSO have concentrated on the Western Pacific warm pool. Very little is known in any detail about the Eastern Pacific, even though the huge upwelling system in this region is an intrinsic part of ENSO dynamics.
