Anthropogenic aerosols have a well-established, definite direct radiative effect: they scatter and reflect incoming solar radiation back to space (the aerosol direct effect), which is more certain and better quantified than their more complex and uncertain indirect effects on cloud formation and atmospheric temperature.
Increasing anthropogenic aerosols definitely increases the amount of solar radiation scattered/reflected back to space (the aerosol direct radiative effect), a well-established and quantifiable physical mechanism....
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