NOAA/WDS Paleoclimatology - Pleistocene Tropical Alkenone Sea Surface Temperature Reconstructions

The nature of the connection between high- and low-latitude climates during the early Pleistocene ŋ41 kyr worldŋ has important implications for our understanding of the feedbacks involved in translating insolation changes into global climate states. Here we focus on the tropical marine record, presenting alkenone-derived sea surface temperature (SST) and productivity records from the eastern equatorial Atlantic, eastern equatorial Pacific, the Arabian Sea, and the South China Sea for a time interval covering the heart of the 41 kyr world (1.2ŋ2.0 Ma). All four SST records are dominated by variance in the obliquity band, suggesting that high-latitude dynamics and low-latitude climate were tightly coupled in the 41 kyr world, despite smaller ice volume variability during this interval as compared to the late Pleistocene. At the 41 kyr period, SST varied coherently and nearly synchronously between the four study regions, suggesting a tropic-wide feedback to high-latitude processes. Productivity variations at our equatorial Atlantic and Pacific sites were also coherent in the obliquity band, implying tropical trade wind variability at this frequency during the early Pleistocene. In contrast, we observe heterogeneous SST and productivity responses in the precession band between each of the tropical locations. Local atmospheric circulation patterns, rather than a globally coordinated response to precessional insolation forcing, apparently determined SSTs and productivity in the tropics at precessional frequencies during the early Pleistocene.