Underestimation of the Tambora effects in North American taiga ecosystems

Fabio Gennaretti,Frank Berninger,Guillermo Gea-Izquierdo,Dominique Arseneault,Etienne Boucher,Martine M Savard,Christian Bégin,Joel Guiot,Antoine Nicault

doi:10.1088/1748-9326/aaac0c

Abstract

The Tambora eruption (1815 AD) was one of the major eruptions of the last two millennia and has no equivalents over the last two centuries. Here, we collected an extensive network of early meteorological time series, climate simulation data and numerous, well-replicated proxy records from Eastern Canada to analyze the strength and the persistence of the Tambora impact on the regional climate and forest processes. Our results show that the Tambora impacts on the terrestrial biosphere were stronger than previously thought, and not only affected tree growth and carbon uptake for a longer period than registered in the regional climate, but also determined forest demography and structure. Increased tree mortality, four times higher than the background level, indicates that the Tambora climatic impact propagated to influence the structure of the North American taiga for several decades. We also show that the Tambora signal is more persistent in observed data (temperature, river ice dynamics, forest growth, tree mortality) than in simulated ones (climate and forest-growth simulations), indicating that our understanding of the mechanisms amplifying volcanic perturbations on climates and ecosystems is still limited, notably in the North American taiga.

Highlights

The Tambora eruption is quite recent in historical terms, its impacts are much better constrained in Europe than elsewhere because of the denser network of historical sources, proxy records and early meteorological stations (Brugnara et al 2015)
Our results suggest a longer persistence of the Tambora signal in some specific Eastern Canada tree-ring proxy records than in the regional climate, which is in accordance with what has been found in Europe (Buntgen et al 2015)
We collected a large amount of data from different and complementary sources over Eastern Canada, to provide an in-depth evaluation of the Tambora impact on climate and forest processes

Summary

Introduction

On 10 April 1815, the Tambora volcano, located in the Sumbawa island in Indonesia, entered into the culminating phase of a large Plinian eruption which had huge local and global impacts on climate, the environment and human societies (Harington 1992, Oppenheimer 2003, Raible et al 2016). Global land temperatures dropped by about 1 ◦C in 1816, which is known as the ‘year without a summer’, and remained low for 6–10 years according to simulation studies (Raible et al 2016) This climatic perturbation occurred during a period of reduced solar irradiance (Dalton minimum) which was impacted by other strong volcanic eruptions (Wagner and Zorita 2005), culminating in one of the coldest episodes of the ‘Little Ice Age’. Many discrepancies exist on the intensity and duration of the Tambora climatic impact as detected by different observed (e.g. weather observations, tree-ring proxies) and simulated records (Buntgen et al 2015) These discrepancies remain largely unexplained because of the poor mechanistic understanding of the responses of the climate and the biosphere at the regional level. We do not know how northern forest ecosystems reacted to the Tambora abrupt perturbation in terms of wood biomass assimilation and forest demography (i.e. tree mortality and recruitment), which are significant components of the regional carbon budget

Methods

Results

Discussion

Conclusion