Large volcanic eruptions reduce landfalling tropical cyclone activity: Evidence from tree rings

Tropical cyclones (TCs) are one of the most devastating storm systems with high socioeconomic impacts around the world. The drivers of long-term changes in TC frequency and intensity, including the recent global climatic changes, are, however, poorly understood due to short instrumental measurements and a lack of accurate proxy records. Here we present the long-term impacts of large volcanic eruptions on TC activity in northeast Asia. For this purpose, we performed a reconstruction of the frequency and intensity of landfalling TCs based on tree-ring oxygen isotope ratios over the past 350 years. Our results revealed markedly depleted delta O-18 values (P < 0.01) for TC years and confirm tree-ring delta O-18 as a strong proxy for the detection of past TCs. The agreement between the delta O-18 chronology and the corresponding TC record (1950-2005) was 96.4% and it was relatively high also for the preceding periods covered by less reliable TC records, specifically 76.1% (1904-1949) and 66.4% (1652-1903). In addition to the prominent TC frequency signal, we found a strong negative correlation (R = -0.65; P < 0.001) between the delta O-18 chronology and TC intensity expressed by the amount of TC precipitation. Our reconstruction revealed that the recent high frequency of landfalling TCs is distinct on a long-term scale. We provide the first long-term evidence of reduced TC activity for two years following large volcanic eruptions. Our results indicate that volcanic ash is a relevant driver of TC activity over northeast Asia via its role on radiative climate forcing. We suggest that large volcanic eruptions modulate large-scale atmospheric and oceanic circulation determining TC genesis and thus TC activity in the western North Pacific. (C) 2021 Elsevier B.V. All rights reserved.