Multi-model ensemble projection of global dust cycle by the end of 21st century using CMIP6 data

Abstract. As a natural aerosol with the largest emissions on land, dust has important impacts on 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 of 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 5 out of 10 models and estimate an ensemble global dust emission of 3311 Tg a⁻¹ (1 Tg = 10¹² g) at present day, in which 75 % is dry deposited and 25 % is wet deposited. Compared to 2005–2014, global dust emissions show varied responses with a reduction of 15.8 Tg a⁻¹ under the SSP3-7.0 scenario but increased emissions up to 53.4 Tg a⁻¹ under the SSP5-8.5 scenario at 2090–2099. For all scenarios, the most significant increase of dust emissions appears in North Africa (0.4 %–4.7 %) due to the combined effects of reduced relative humidity and precipitation but strengthened surface wind. In contrast, all scenarios show decreased emissions in central Asia (−0.6 % to −20 %) and Middle East (0 to −2.8 %) because of the increased precipitation but decreased wind speed regionally. The dust loading shows uniform increases over North Africa (1 %−12.5 %) and the downwind Atlantic following the increased emissions, but decreases over East Asia (−3.4 % to −15.2 %) and the downwind Pacific due to enhanced local precipitation that promotes wet deposition. As a result, global dust loading will increase by 2.1 %–9.3 % at the end of the 21st century under different climate scenarios, suggesting a likely strengthened radiative and climatic perturbations by dust aerosols in a warmer climate.