Seasonally-resolved records of past climate states provide an important means of assessing climate models. They also allow an evaluation of any seasonal bias in non-seasonally resolved climatic parameters.This is important as secular changes in the amplitude of seasonality are a driver of environmental and climatological change under different greenhouse gas regimes. However, past seasonality is poorly constrained, to be addressed here as advances in analytical techniques allow (sub-)seasonal to daily time resolution in a variety of proxy archives.
Objectives of the individual project
- Fieldwork and sampling of long-lived molluscs (e.g. Tridacna), large benthic foraminifera or corals in Pliocene and Holocene strata; sample characterization including diagenetic overprint
- Acquisition of decade-long, continuous time series of temperature, salinity, upwelling etc. at seasonal or even daily resolution, utilizing geochemical proxies from spatially-resolved analysis such as laser-ablation mass spectrometry (LA-ICPMS) or micromilling, including clumped-isotope (?47) analysis. This will provide constraints on the secular temperature evolution of the Pacific Warm Pool (PWP), and how that is related to seasonality.
- Evaluation and application of recently-developed proxies such as Mg/Ca or Sr/Ca in Tridacna (Warter, Müller et al. 2018) as indicators of light intensity, crucial in turbid reef settings.
The datasets produced in this project will provide a better quantitative understanding of past tropical seasonality, including the possible reconstruction of past turbidity. This project will also provide input for climate modelling (ESR15) and facilitate comparison between seasonally-resolved palaeoenvironmental parameters and Earth System models.