Multi-model ensemble projection of the global dust cycle by the end of 21st century using the Coupled Model Intercomparison Project version 6 data

Abstract

As a natural aerosol with the largest emissions on land, dust has important impacts on the atmospheric environment and climate systems. Both the emissions and transport of dust aerosols are tightly connected to meteorological conditions and as a result are confronted with strong modulations by the changing climate. Here, we project the changes in the global dust emissions and loading by the end of the 21st century, using an ensemble of model outputs from the Coupled Model Intercomparison Project version 6 (CMIP6) under four Shared Socioeconomic Pathways (SSPs). Based on the validations against site-level observations, we select 9 out of 14 models and estimate an ensemble global dust emissions of 2566 ± 1996 Tga-1 (1 Tg Combining double low line 1012 g) for the present day, in which 68 % is dry deposited and 31 % is wet deposited. Compared to 2005-2014, global dust emissions show varied responses, with a reduction of -5.6 ± 503 Tga-1 under the SSP3-7.0 scenario but increased emissions up to 60.7 ± 542 Tga-1 under the SSP5-8.5 scenario at 2090-2099. For all scenarios, the most significant increase in the dust emissions appears in North Africa (0.6 %-5.6 %) due to the combined effects of reduced precipitation but strengthened surface wind. In contrast, all scenarios show decreased emissions in the Taklimakan and Gobi deserts (-0.8 % to -11.9 %) because of the increased precipitation but decreased wind speed on a regional scale. The dust loading shows uniform increases over North Africa (1.6 %-13.5 %) and the downwind Atlantic, following the increased emissions but decreases over East Asia (-1.3 % to -10.5 %), and the downwind Pacific, partly due to enhanced local precipitation that promotes wet deposition. In total, global dust loading will increase by 2.0 %-12.5 % at the end of the 21st century under different climate scenarios, suggesting a likelihood of strengthened radiative and climatic perturbations by dust aerosols in a warmer climate.