American Meteorological Society

Assessing the impact of volcanic eruptions on climate extremes using CMIP5 models

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This study analyzes extreme temperature and precipitation responses over the global land to five explosive tropical volcanic eruptions that occurred since the 1880s, using CMIP5 multi-model simulations. Changes in annual extreme indices during post-eruption years are examined using a composite analysis. First, a robust global decrease in extreme temperature is found, which is stronger than the internal variability ranges (estimated from random bootstrap sampling). Inter-model correlation analysis shows a close relationship between annual extreme and mean temperature responses to volcanic forcing, indicating a similar mechanism at work. The cooling responses exhibit strong inter-model correlation with a decrease in surface humidity, consistent with the Clausius-Clapeyron relation. Second, extreme and mean precipitation reductions are observed during post-eruption years, especially in Northern and Southern Hemisphere summer monsoon regions, with good inter-model agreement. The precipitation decreases are also larger than the internal variability ranges and are dominated by the monsoon regions. Moisture budget analysis further reveals that most of the precipitation decrease over the monsoon regions is explained by evaporation decrease, as well as dynamic and thermodynamic contributions. Interestingly, the dynamic effect is found to have a large influence on inter-model spread in precipitation responses, with high inter-model correlation with mean and extreme precipitation changes. These model-based results are largely supported by an observational analysis based on the HadEX2 data set for the recent three volcanic eruptions. Our results demonstrate that temperature and precipitation extremes significantly respond to volcanic eruptions, largely resembling mean climate responses, which provides an important implication for geoengineering based on solar radiation management.

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