(3) increasing the flux of biogenic aerosols (DMS, isoprenes etc) being put into the atmosphere and hence the global concentration of CCN (Cloud Condensation Nuclei).
But as you may know, I am talking about the rising leading edges of AOT plots which relate to early stage cloud formation (i.e. nucleation — presumably via DMS, isoprenes etc emitting by cyanobacterial blooming).