講演情報
[AAS08-P43]Projected changes in natural aerosols and their effects on radiation and clouds
*若松 彩1、河合 慶1、黒崎 豊2、松井 仁志1 (1.名古屋大学環境学研究科、2.北海道大学低温科学研究所)
キーワード：
自然起源エアロゾル、人為起源エアロゾル、全球気候モデル、エアロゾル雲相互作用、将来気候変化
Global warming is progressing at an unprecedented rate due to increasing greenhouse gas emissions. In contrast, atmospheric aerosols scatter and absorb solar radiation and act as cloud condensation nuclei (CCN), enhancing cloud albedo and exerting a cooling effect that partly offsets warming. While anthropogenic aerosol emissions are projected to decrease in the future, natural aerosol emissions are projected to increase in a warmer climate. However, the combined effects of simultaneous changes in multiple natural aerosol sources under strong warming remain poorly understood. In this study, we quantify changes in natural aerosol emissions from the 2010s to the 2090s under the SSP5-8.5 scenario and examine their impacts on radiation and clouds using a global climate-aerosol model. We also quantify the contributions of individual aerosol species to changes in AOD and CCN.
Our simulations show that global warming increases natural emissions of aerosols and their precursors by 26%, mainly reflecting increased emissions of biogenic volatile organic compounds and sea salt. As a result, global-mean aerosol optical depth (AOD) and CCN concentrations increase by 30% and 12%, respectively, from the 2010s to the 2090s. The increase in AOD from natural aerosols (+0.023) exceeds the decrease from anthropogenic aerosol reductions (–0.018). Similarly, the increase in CCN from natural aerosols offsets roughly half of the decrease from anthropogenic aerosol reductions.
These results suggest that warming-induced increases in natural aerosols substantially counteract the effects of anthropogenic aerosol reductions. In the presentation, we will further discuss how these changes influence the radiative balance through aerosol-radiation and aerosol-cloud interactions.
Our simulations show that global warming increases natural emissions of aerosols and their precursors by 26%, mainly reflecting increased emissions of biogenic volatile organic compounds and sea salt. As a result, global-mean aerosol optical depth (AOD) and CCN concentrations increase by 30% and 12%, respectively, from the 2010s to the 2090s. The increase in AOD from natural aerosols (+0.023) exceeds the decrease from anthropogenic aerosol reductions (–0.018). Similarly, the increase in CCN from natural aerosols offsets roughly half of the decrease from anthropogenic aerosol reductions.
These results suggest that warming-induced increases in natural aerosols substantially counteract the effects of anthropogenic aerosol reductions. In the presentation, we will further discuss how these changes influence the radiative balance through aerosol-radiation and aerosol-cloud interactions.