Eurasian Holocene climate trends in transient coupled climate simulations and stable oxygen isotope records

Abstract

Transient simulations of the global fully coupled climate model COSMOS under realistic varying orbital and greenhouse gas forcings are systematically compared to diatom oxygen isotope ( δ 18 O 0.1em diatom0.1em) records from Russian lakes with focus on Eurasian Holocene climate trends. The measured δ 18 O 0.1em diatom0.1em decrease and other temperature proxies are interpreted as large‐scale cooling throughout the Holocene while the model simulations are biased too warm, likely through missing radiative forcings. This large‐scale warm bias also dictates the modeled δ 18 O 0.1em precipitation. Hence, at locations where the signs of model and proxy temperature/precipitation trends agree, measured δ 18 O 0.1em diatom0.1em and modeled δ 18 O 0.1em precipitation0.1em trends show notable accordance. An increased temporal variability of modeled δ 18 O 0.1em precipitation0.1em is linked to persistent atmospheric circulation patterns. Applying the transient forcings in an accelerated way (every 10th year only) yields a similar, yet weaker or delayed model response, especially in the ocean.

Quaternary environmental and climatic history of the northern high latitudes – recent contributions and perspectives from lake sediment records

“…The dating methods employed are also highly variable, selectively comprising radiocarbon dating, luminescence dating, tephrochronology, palaeomagnetic dating, and varve chronology; a few papers utilise previously published age-depth models. Danek et al (2022) present trends in δ 18 O values of diatom frustules throughout the past 7 ka, which were determined on sediment records from the Eurasian lakes Ladoga, Bolshoye Shchuchye, Kotokel, Emanda, El'gygytgyn and Two-Yurts (Table 1, Fig. 1).…”

“…Danek et al . (2022) present trends in δ 18 O values of diatom frustules throughout the past 7 ka, which were determined on sediment records from the Eurasian lakes Ladoga, Bolshoye Shchuchye, Kotokel, Emanda, El'gygytgyn and Two‐Yurts (Table 1, Fig. 1).…”

“…1) are sorted counter-clockwise starting at the Greenwich meridian (0°). Note that some lake records are discussed in more than one paper and that Danek et al (2022), Haflidason et al (2022 and Miller et al (2022) discuss data from more than one lake. TC: total carbon; TIC total inorganic carbon; TN: total nitrogen; TOC: total organic carbon; TS: total sulphur; XRF: X-Ray Fluorescence.…”

A global compilation of diatom silica oxygen isotope records from lake sediment – trends, and implications for climate reconstruction

“…The predictability of isotope fractionation processes in the water cycle due to clear physical constraints allows for using δ 18 O not only as a quantitative tool for past (hydro)climate reconstructions, but also for implementing δ 18 O in global climate models (e.g. Danek et al 2021). However, challenges persist in understanding and comparing data and model outputs, partly due to complex signal formation in environmental archives (Danek et al, 2021).…”

“…Danek et al 2021). However, challenges persist in understanding and comparing data and model outputs, partly due to complex signal formation in environmental archives (Danek et al, 2021). Lake sediments are prominent and widespread archives in terrestrial environments (Leng, 2006;Biskaborn et al, 2016;Subetto et al, 2017).…”