This Milankovic Medalist paper represents a tour de force, addressing a complex yet crucial question: the evolution of global climate over the past 4.5 million years. This paper makes a significant contribution to the geoscience community by providing a self-consistent decomposition of global mean benthic δ18O into its temperature and seawater (ice volume) components. This approach is consistent with independent estimates of global mean sea surface temperature (GMSST) and sea level constraints.The analysis incorporates numerous high-resolution records spanning this period and highlights two distinct climatic regimes: • Before 1.5 million years ago, a warm period characterized by smaller-amplitude ice sheet and sea level cycles, primarily driven by obliquity timescales. • Following the Mid-Pleistocene Transition (MPT), i.e. after 1 million years, a well-documented increase in the amplitude of glacial cycles became evident. The central finding of the study is that, during the MPT, there was a shift in ocean heat storage efficiency (HSE). Prior to this transition, HSE remained low and constant, whereas after the MPT, it doubled and stabilized at a higher value. This finding is supported by the observation of subtle differential changes in global mean SST and mean ocean temperature (MOT), which appear to be time-dependent. These observations suggest a potential fundamental shift in oceanic heat storage dynamics.

This manuscript deserves to be highlighted as it presents an incredible dataset, analysed using state-of-the-art techniques and summarised in a clear and readable form. As the reviewers pointed out, the content could easily have resulted in two articles (or even more...) - a practice that is sometimes done to increase ‘academic output’. However, the authors have chosen to provide a comprehensive overview and interpretation of the results. In addition, the site studied is of great importance for Icelandic studies of Holocene climate change.

The article by Darrell Kaufman and Valérie Masson-Delmotte provides a useful Opinion piece on the inclusion of paleoscience in the upcoming IPCC AR7.

The Atlantic Meridional Overturning Circulation (AMOC) is at its weakest of the last millennium and is projected to further weaken over the coming decades, with the risk of a collapse over the coming century non negligible. The geologic record provides examples of rapid and large AMOC variations, with phases of AMOC weakening, preceding an AMOC shutdown. One key question is whether CO2-driven AMOC weakening is reversible, or whether it represents a tipping point, which might lead to an AMOC collapse. The study by Willeit et al. offers a new diagnostic that is simple to implement and allows for comparing AMOC stability between different models, as well as different time periods. This offers a powerful new tool in understanding the conditions for AMOC stability, and thus the AMOC future.

Understanding the stability of the Antarctic ice sheet during the Pliocene has important implications to future Antarctic ice sheet changes and sea level. However, changes in the eastern Antarctic ice sheet are still largely unknown. This work may provide key geological evidence to fill in this knowledge gap.

These data are unique to Greenland, particularly from the base of the Camp Century ice core. These data, which show several periods of glaciation and non-glaciation in northwest Greenland prior to the formation of the current ice cap, should be of great interest to the paleo community, from paleoecologists to modelers.

This study employs novel methods to evaluate wildfire activity in southern Siberia during past warm periods, exploring its connections to vegetation and climate. The findings reveal that fire activity was more pronounced during the Last Interglacial than in the Holocene, driven by warmer summers and the prevalence of open forests. These results underscore the compounded influence of both vegetation changes and climate shifts on wildfire activity.

The paper presents a state-of-the-are Holocene reconstruction of North American vegetation shifts, including a discussion of drivers and potential feedbacks on climate.