Climate of the Past 

This paper presents the first gridded reconstruction of the summer (June, July, and August) vapor pressure deficit (VPD) for the past four centuries at the European level. The reconstruction shows that from the mid-1700s, a trend towards higher summer VPD occurred in Central Europe and the Mediterranean region, a trend that has continued through the observational period. The reconstruction is based on 26 European tree-ring oxygen isotope records .

The paper submitted by Meister and colleagues presents the first comprehensive compilation and assessment of diatom oxygen isotope records in lake sediments (δ18OBSi). The authors have supplemented these data with additional lake basin parameters (such as catchment size and residence times). The manuscript first infers the spatial and temporal coverage of δ18OBSi records and then discusses common hemispheric trends on centennial and millennial time scales, with key results such as: - Common patterns for hydrologically open lakes in extra-tropical regions of the Northern Hemisphere. - Common trends during the Common Era and throughout the Holocene corresponding to known climatic epochs such as the Holocene Thermal Maximum, Neoglacial cooling, the Medieval Climate Anomaly and the Little Ice Age. This is a well-written manuscript that should make a valuable contribution to reconstructions of past climates.

Reconstructing large-scale climate patterns from sparse local records is crucial for understanding past climates. Yet, it remains challenging to derive those reconstructions due to the patchiness, uneven spatial distribution, and disparate nature of palaeoclimatic proxy records. In this study, Eichenseer and Jones developed a Bayesian hierarchical model to integrate ecological data with established geochemical proxies into a unified quantitative framework, which bridges the gap in the latitudinal coverage of proxy data. They showed that this framework has the potential to enhance quantitative palaeoclimatic reconstructions especially the latitudinal temperature gradient estimated from datasets with limited spatial sampling.

The Generalized Milankovitch Theory (GMT) presented and discussed in this paper provides a new view on the long-standing problem raised by the Milankovitch theory of glacial-interglacial cycles. The GMT is based on a deep insight into theory, data, and numerical modeling. It condensates the profound knowledge into a fascinatingly elegant dynamic systems theory.

The manuscript by Skinner et al. presents a unique and useful data compilation of ocean-atmosphere radiocarbon age offset (B-Atm) across the last deglaciation. The presented global average B-Atm represents a new benchmark for modelling studies seeking to constrain the ocean's role in past atmospheric CO2 change, and seeking closure of the global radiocarbon cycle. The latter is important for constraining the carbon cycle evolution over the last deglaciation (which remains to be quantitatively accounted for), as well as the history of the geodynamo and solar activity.