Absence of Winter Warming in Eurasia following large, tropical volcanic eruptions during the Last Millennium

In this investigation, we reassess the hypothesis that volcanic eruptions lead to surface warming in Eurasia during winter. This reevaluation is grounded in contemporary modeling studies that propose internal climatic variations might dominate over the volcanic-forced responses. Our analysis is centered on the Last Millennium (LM), where we combine model output, instrumental observations, tree-ring records, and ice cores, and build a new temperature reconstruction that specifically targets the boreal winter season. Utilizing the latest advancements in volcanic forcing reconstructions, we pinpoint 20 volcanic events over the LM with volcanic stratospheric sulfur injections (VSSI) exceeding those of the 1991 Pinatubo eruption.Our analysis indicates that among the 20 major volcanic events identified, only seven resulted in warmer surface temperature anomalies in Eurasia during the initial winter following the eruption. In scrutinizing the 13 occurrences that exhibit cold post-eruption anomalies, we observe no direct correlation between the extent of winter cooling and the mass of volcanic stratospheric sulfur injections (VSSI), suggesting that significant internal climatic variability is the probable driver of these cold anomalies.Moreover, we compare our new temperature reconstruction with two independent reconstructions, and successfully harmonize our results with those of prior research. Moving beyond the observational uncertainties and the conflation of eruptions from different latitudes and different post-eruption winters, our study challenges previous assertions of post-eruption winter warming that largely stemmed from the superposed epoch analysis, which involved averaging the effects of smaller eruptions with larger ones. Our comprehensive observational findings, encompassing the entire LM and corroborating many recent climate modeling studies, suggest that substantial low-latitude volcanic eruptions, such as the 1991 Mount Pinatubo eruption, do not lead to any notable surface warming during the winter months in Eurasia.