A Fossil Pollen--Based Spatio-Temporal Reconstruction of the Paleoclimate

• Activity Number: 404
• Type: Contributed
• Date/Time: Tuesday, August 5, 2014 : 2:00 PM to 3:50 PM
• Sponsor: Section on Statistics and the Environment
• Author(s): Lasse Holmstrom*+ and Liisa Ilvonen and Heikki Seppa and Siim Veski
• Companies: University of Oulu and University of Oulu and University of Helsinki and Tallinn University of Technology
• Keywords: Bayesian modeling ; Paleoclimate ; Regression ; Space-time modeling ; Temperature proxy

Abstract

Holocene (the last 12 000 years) temperature variation is reconstructed at multiple locations in southern Finland, Sweden and Estonia, based on pollen fossil data from lake sediment cores. A novel Bayesian statistical approach is proposed that allows the reconstructed temperature histories to interact through shared environmental response parameters and spatial dependence. The prior distribution for past temperatures is partially based on numerical climate simulation.The main patterns of the reconstructions are the marked rise of mean annual temperature from the early Holocene to the Holocene thermal maximum in northern Europe, followed by a gradual cooling towards the present. A brief cold episode is indicated 8200 years ago at two sites with particularly high sample resolution. These features are consistent with the quantitative climate reconstructions based on more commonly used reconstruction techniques. The results suggest that the novel spatio-temporal approach can provide reconstructions that are smoother, less uncertain and generally more realistic than the site-specific individual reconstructions.