Climate response to the 1815 Mount Tambora Eruption: Analysis of a Multi-model Simulation Ensemble

Abstract

This Thesis explores the climatic impacts of the 1815 Mount Tambora eruption, an event that significantly altered global climate patterns, notably causing the "year without summer" in Europe the following year. The study uses an ensemble of simulations of the Tambora eruption with three climate models (MPIESM1-2L, CanESM5, and MIROC), each generating nine realizations, to discern whether the diversity of climate responses in the multi-model ensemble is determined more by model specificities than by the initial conditions, here determined by El Niño Southern Oscillation (ENSO). The Thesis work is structured as follows. First, a review is made of the state-of-the-art knowledge about the Mount Tambora eruption and its consequences on the global climate, and information about the models and the Tambora experiment is acquired. Then, data from the multi-model ensemble is acquired and pre-processed, to homogenize the spatial structure of the data. Then, the study delves into the description and application of mathematical and statistical tools for data analysis, including principal component and cluster analysis. The analysis is conducted on seasonal anomalies of near-surface air temperature for winter and summer of 1816. The results reveal the diversity of post-eruption anomalies within each model and across different models, suggesting a relevant contribution by noise/initial condition dependencies. Model specificities remain substantial even when excluding the noisy components, indicating that multiple response mechanisms exist, and that these are differently represented in the considered models. The Thesis ends with a discussion of the results and an outlook on possible future developments of the work.