My hunch is that ocean circulation patterns were different enough to cause the warm decade globally. Intriguingly, though, El Ninos were weak in the 1930s, and El Nino years (like 1998) are usually the warmest years.
Indicates Maunder Minimum irradiance was lower by 0.37% (minimum) to 1.23% (maximum) -- a lot more than 0.1%.
And apparently the Dust Bowl was a local phenomenon; your link mentions the connection between a cool tropical Pacific and droughts.