Approaches to identifying Dansgaard-Oeschger events in pollen records and quantitative climate reconstructions ...

• Main Author: Turner, Mark Grenville
• Format: Thesis
• Language: unknown
• Published: University of Reading 2024
• Subjects: Greenland; Dansgaard-Oeschger events
• Online Access: https://dx.doi.org/10.48683/1926.00115579; https://centaur.reading.ac.uk/id/eprint/115579

The warmings associated with Dansgaard-Oeschger cycles (D-Os) during the last glacial were as fast as and of a similar magnitude to expected warming over the 21st century. Identifying these warmings in pollen records objectively may assist understanding of current and future climate change impacts. Identification of D-Os by age alone is hampered by dating uncertainties in both Greenland and pollen core age-depth models, so additional methods of identification are sought. Several statistical techniques applied directly to pollen series from the circum-Mediterranean area do not show D-Os clearly and consistently. An alternative approach using quantitative climate reconstructions made using WA-PLS and fxTWA-PLS is explored. First, the robustness of these methods is evaluated. A training set should sample a climate space which includes the target climate as comprehensively as possible. Actual distributions of taxon abundances along climate gradients often differ from the symmetrical unimodal shape assumed by ...