Dust in the atmosphere

At www.physorg.com/print195145467.html … in the Proceedings of the National Academy of Sciences it is being said that dust and pollen in the atmosphere causes higher levels of precipitation in clouds. It is now thought clouds have a greater cooling effect on the weather than previously admitted. This change of tack has come about because of extended research into clouds and their role in global warming. However, taking this to its logical conclusion might dust in the atmosphere, from volcanoes or of cosmic origin, have had in the past an influence on climate,