What are your thoughts on the Wild et al. global dimming paper?

I think they have a problem with the PDO phase shift which occured in the late 70's which has been proven to change the amount of solar surface radiation the planet receives by modulating the amount of cloud cover, as well as the fact that there was significant volcanic activity in the 60's 80's and early 90's that would confuse any study of anthropogenic aersol content until say 1995. After that date there has been no significant volcanic activity that has altered the amount of surface radiation received, and consequently the planet has warmed up rather quickly. Which many people confuse as being AGW.