Possible Influence of Volcanic Activity on the Decadal Potential Predictability of the Natural Variability in Near‐Term Climate Predictions

Hideo Shiogama,Masayoshi Ishii,Toru Nozawa,Sayaka Yasunaka,Masahide Kimoto,Seita Emori,Takashi Mochizuki,Tokuta Yokohata

doi:10.1155/2010/657318

Abstract

Initialization based on data assimilations using historical observations possibly improves near‐term climate predictions. Significant volcanic activity in the future is unpredictable and not assumed in future climate predictions. To examine the possible influence of unpredictable future volcanic activity on the decadal potential predictability of the natural variability, we performed a 2006–2035 climate prediction experiment with the assumption that the 1991 Mt. Pinatubo eruption would take place again in 2010. The Pinatubo forcing induced not only significant cooling responses but also considerable noises in the natural variability. The errors due to the Pinatubo forcing grew faster than that arising from imperfect knowledge of the observed state, leading to a rapid reduction of the decadal potential predictability of the natural variability.

Highlights

Near-term climate predictions up to the year 2035 are useful for adaptation to the possible consequences of rapid climate changes and will be highlighted in the assessment report of the Intergovernmental Panel on Climate Change (IPCC) [1,2,3,4,5]
To investigate possible influences of the volcanic forcing on the potential predictability of the natural variability, we examined the normalized ensemble variances [12, 13], E≡
It was suggested that the potential predictability of the global mean natural variability would soon diminish

Summary

Introduction

Near-term climate predictions up to the year 2035 are useful for adaptation to the possible consequences of rapid climate changes and will be highlighted in the assessment report of the Intergovernmental Panel on Climate Change (IPCC) [1,2,3,4,5]. Climate modeling centers are exploring the possibility that an initialization based on assimilations of observed historical data assists in the prediction of the decadal natural variability in near-term predictions [9, 12,13,14,15,16,17,18,19,20,21]. By including the stochastic fluctuations of natural external factors based on historical forcing, Bertrand et al [23] examined the potential influences of natural external forcing factors. They suggested that natural external forcing might exert significant influences on anthropogenic global warming in the coming decades

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