There is a recent report by the UN which deals with this problem.
The report says ABC's produce surface cooling, but warming of the upper atmosphere, resulting in reduced rainfall and snowfall at high elevations.
This is currently having a profound effect on the water supply of India.
Here is a link to the UN report
A discussion of this man made phenomenon can be found at:
The report states changes induced by ABCs with high confidence:
It is certain that ABCs have caused dimming at the surface.
It is certain that soot in ABCs has increased solar heating of the atmosphere.
It is virtually certain that India and China are dimmer (at the surface) today by at least 6 per cent, compared with the pre-industrial values. Absorbed solar radiation at the surface in China and India are lower today by 15 W m-2 or more, compared with the pre-industrial values.
It is highly likely that black carbon (BC) in ABCs has increased the vertically averaged annual mean solar absorption in the troposphere (from the surface up to 14 km in altitude) by about 15 per cent (about 14 W m-2) and the solar heating at elevated levels (1 - 4 km) over India and China by as much as 20 - 50 per cent (6 - 20 W m-2).
Overall, the report concludes that ABCs represent a serious threat to human health and food security, and that the problem is already becoming serious in large regions of Asia. But in a disturbing damned-if-you-do-and-damned-if-you-don’t, eliminating ABCs will also remove the mitigating effect on greehouse-gas warming:
… aerosols in ABCs have masked 20 - 80 per cent of GHG forcing in the past century.