Combining a new record of bipolar volcanism from Greenland and Antarctic ice cores with records of abrupt climate change derived from the same ice cores, this study provides the most convincing evidence yet of the influence of large volcanic eruptions on long term climate variability, namely Dansgaard-Oeschger warming events. This should garner significant popular interest.

This study presents a novel Monte Carlo Empirical Orthogonal Function analysis that combines a dense isotopic proxy network with isotope-enabled climate models to study dynamics and variability of South American Monsoon System (SAMS) over past millennium. This analysis reveals that the leading modes of SAMS variability over the past millennium are regionally stable, arising independently of external forcing (solar, volcanic, orbital). Significant enhancement of the SAMS is accompanied by southward displacement of the South Atlantic Convergence Zone during the Little Ice Age, giving rise to a strengthened South American precipitation dipole. Proxy-model comparison demonstrates outstanding mismatches in centennial-scale hydroclimate departures during the Medieval Climate Anomaly and Little Ice Age from the last millennium mean state. The results of last millennium SASM variability contextualizes modern variability of SASM. The identified proxy data-model mismatch raises a key question to climate simulations of SASM variability, which may attract broad attention from paleoclimate modeling community. Moreover, the reported methodology can be applied to paleoclimate problems of various spatial and temporal scales and is of relevance for the broader geoscience community.

Huhtamaa et al. assess the socioeconomic consequences of 17th century volcanic eruptions in Fennoscandia. They find that while all the eruptions led to poor grain harvest in the region through their climatic impact, the socioeconomic response varied. They suggest that the micro-regional socioeconomic system modulated the socioeconomic response to each eruption. Such a framework should be used to further our understanding of the impact of volcanic eruptions on societal crises.

The paper presents an interesting review of deep time ecosystems and suggests that the interpretation of the evolution of ancient sedimentary systems can be refined and better compared to today’s changes in ecosystems. Concerning the rate of climate change, this study implies that anthropogenically induced global warming and subsequent sea level rise today occurs more than ten times faster than the fastest rise reconstructed for the Oxfordian (159 Ma - 154 Ma)