Pollen-based climatic reconstructions for the interglacial analogues of MIS 1 (MIS 19, 11 and 5) in the Southwestern Mediterranean: insights from ODP Site 976

Abstract. Pleistocene interglacials, specifically MIS 19, 11 and 5, have been suggested as analogues of MIS 1 due to similar solar forcing patterns, greenhouse gas concentrations and sea levels. There has been substantial debate regarding which of these is the most suitable analogue and so far there has been no consensus, although what really emerges from recent work is the high variation in regional climate during these periods. One of the limiting factors in our understanding of these potential analogues is the fact that very few long-sequences cover the entire duration of these interglacials at high resolution.

In this study, a multi-method approach is used to produce climatic reconstructions for MIS 19, 11, 5 and 1, using pollen data derived from a single long marine core from ODP Site 976. This represents the first study which attempts to use pollen-based climatic reconstructions to compare MIS 1 with its analogues, representing a necessary contribution to the debate with a focus on the relationships between vegetation and climate in the southwestern Mediterranean.

Three methods of quantitative climate reconstruction have been adopted: the more widely used methods Modern Analogues Technique (MAT) and Weighted Average Partial Least Squares regression (WA-PLS), and a more recent machine-learning method known as Boosted Regression Trees (BRT). The reconstructions show consistent changes in temperature and precipitation during MIS 19, 11, 5 and 1, which correlate well with climatic changes observed in other regional and global proxies, and highlight distinct climatic characteristics of each interglacial period in the southwestern Mediterranean. MIS 19 exhibits high variability and colder temperatures compared to subsequent interglacials and the MIS 1. Conversely, MIS 11 displays warmer temperatures and greater stability, which makes it a useful analogue to understand prolonged interglacials, crucial considering the anthropogenic impacts on the duration of warm climate during the Holocene. MIS 5 exhibits overall warmer conditions, and its higher temperature coupled with fluctuations in solar forcing makes it a less suitable MIS 1 analogue.

Although past interglacials do not offer direct predictions for the Holocene's future, they provide essential insights into Earth's responses to various forcing factors, serving as crucial benchmarks for understanding the Mediterranean's sensitivity to global changes.