Abstract
Abstract. The “1809 eruption” is one of the most recent unidentified volcanic eruptions with a global climate impact. Even though the eruption ranks as the third largest since 1500 with a sulfur emission strength estimated to be 2 times that of the 1991 eruption of Pinatubo, not much is known of it from historic sources. Based on a compilation of instrumental and reconstructed temperature time series, we show here that tropical temperatures show a significant drop in response to the ∼ 1809 eruption that is similar to that produced by the Mt. Tambora eruption in 1815, while the response of Northern Hemisphere (NH) boreal summer temperature is spatially heterogeneous. We test the sensitivity of the climate response simulated by the MPI Earth system model to a range of volcanic forcing estimates constructed using estimated volcanic stratospheric sulfur injections (VSSIs) and uncertainties from ice-core records. Three of the forcing reconstructions represent a tropical eruption with an approximately symmetric hemispheric aerosol spread but different forcing magnitudes, while a fourth reflects a hemispherically asymmetric scenario without volcanic forcing in the NH extratropics. Observed and reconstructed post-volcanic surface NH summer temperature anomalies lie within the range of all the scenario simulations. Therefore, assuming the model climate sensitivity is correct, the VSSI estimate is accurate within the uncertainty bounds. Comparison of observed and simulated tropical temperature anomalies suggests that the most likely VSSI for the 1809 eruption would be somewhere between 12 and 19 Tg of sulfur. Model results show that NH large-scale climate modes are sensitive to both volcanic forcing strength and its spatial structure. While spatial correlations between the N-TREND NH temperature reconstruction and the model simulations are weak in terms of the ensemble-mean model results, individual model simulations show good correlation over North America and Europe, suggesting the spatial heterogeneity of the 1810 cooling could be due to internal climate variability.
Highlights
The early 19th century (∼ 1800–1830 CE), at the tail end of the Little Ice Age, marks one of the coldest periods of the last millennium (e.g., Wilson et al, 2016; Past Global Changes (PAGES) 2k Consortium, 2019) and is of special interest in the study of inter-decadal climate variability (Jungclaus et al, 2017)
Peak temperature anomalies across the experiments correlate with the magnitude of prescribed AOD (Fig. 1a), and the responses are qualitatively consistent with expectations; the AOD for the Low and nNHP experiments, which is similar in magnitude to that from the observed 1991 Pinatubo eruption, leads to global-mean temperature anomalies similar to those observed after Pinatubo
Our aim was to address the question of whether or not the short-term climate response to the 1809 eruption noted in observations and proxy-based climate reconstructions is compatible with a range of volcanic forcing estimates constructed based on estimated uncertainties in volcanic stratospheric injection from ice-core records
Summary
The early 19th century (∼ 1800–1830 CE), at the tail end of the Little Ice Age, marks one of the coldest periods of the last millennium (e.g., Wilson et al, 2016; PAGES 2k Consortium, 2019) and is of special interest in the study of inter-decadal climate variability (Jungclaus et al, 2017). It was influenced by strong natural forcing: a grand solar minimum (Dalton Minimum, ∼ 1790–1820 CE) and simultaneously a cluster of very strong tropical volcanic eruptions that includes the widely known Mt. Tambora eruption in 1815, an unidentified eruption estimated to have occurred in 1808 or 1809, and a series of eruptions in the 1820s and 1830s. Tambora eruption in April 1815 was the largest in the last 500 years and had substantial global climatic
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