Aerosols - small particles suspended in the atmosphere - have a variety of effects that directly or indirectly affect climate concerns. Not all aerosols have the same effects.

Aerosols that scatter — such as sulphates, nitrates and organic carbon — tend to cool the Earth by sending some incoming radiation back into space, while absorbing aerosols, such as black carbon (formed from the incomplete burning of fossil fuels), heat up the Earth’s atmosphere.

Scattering aerosols also can affect plant growth, for example by allowing more light to penetrate below the canopy and promote growth at lower levels without reducing growth in the canopy. Absorbing aerosols fall out and alter the albedo of land and ice, and have been cited as culprits in arctic melting.

. . . calculations based on satellite measurements assume that the relative concentrations of different aerosols in the atmosphere have remained constant throughout the industrial age. This is a problem because calculating the cooling effect of anthropogenic aerosols involves subtracting the effect of aerosols naturally present in the atmosphere, in other words working out the relative strength of scattering and absorption before the industrial era. It turns out, in fact, that emissions of black carbon have increased by more than a factor of six whereas output of the various scattering aerosols has gone up by a factor of only three or four. . .

Myhre calculates a new best estimate of -0.3 Wm-2 for the cooling of the direct aerosol effect. He says that this will tend to reduce future projections of global warming. This is because the expected drop in aerosol production will not lead to as large a temperature rise as previously thought. Indeed, he estimates that the direct aerosol effect offsets only 10% of global warming. However, he points out that there is still some uncertainty in the vertical distribution of aerosols within the atmosphere, which is significant in so far as absorptive aerosols have a much greater effect when located above a cloud than when below.

Myhre also points out that the direct aerosol effect is smaller than another phenomenon known as the “indirect” effect, in which aerosols enhance scattering through cloud formation. The IPPC’s estimate for the indirect effect is -0.7 Wm-2, ranging from -1.8 Wm-2 to -0.3 Wm-2. Edwin Cartlidge

There may be a drop in inadvertent aerosol production, but if it is a drop in those that absorb light the effect will be cooling, and since they seem to have increased the most it may be that the net effect of hacking the spew may be cooling. And, some geoengineering notions are to shoot scattering aerosols into the upper atmosphere. It's cheap enough that many nations, or even some rich individuals, could do this alone. Unilateral climate engineering.