Atmospheric aerosols play a key role in the Earth’s system by interacting with radiation, clouds, chemistry, and biogeochemistry, thereby affecting climate, air quality, hydrological and biogeochemical cycles. In this presentation, I will show results on the climate impact of agricultural dust (AD) and volcanic ash (VA) through their interactions with clouds by acting as ice nucleating particles (INPs). We examine the global distribution and seasonal variability of AD impacts on mixed-phase cloud properties and the Earth’s radiation budget. By analyzing satellite observations of cirrus microphysics and aerosol extinction we show that microphysics of midlatitude cirrus clouds is altered by the enhanced stratospheric aerosol loadings produced by moderate-magnitude midlatitude explosive eruptions, indicative of heterogeneous ice nucleation on VA suppressing the homogeneous freezing. This motivates us to quantify the efficacy of cirrus cloud thinning (CCT) by injecting dust INPs in a global climate model with improved representations of ice nucleation and gravity waves.