Does the climate have any effect on plate tectonics?
According to the article Cenozoic climate change as a possible cause for the rise of the Andes, the climate could affect mountain building by altering the amount of erosion, and therefore sediment deposits, which could act as a lubricant in subduction zones. In the example given, the lack of sediment increased friction, causing "crumpling" and the building of the Andes.

Given that the climate impacts erosion, that erosion may then affect the stress loading of thrust faults, affecting the earthquake frequency and magnitude, the same as post-glacial rebound.

Isostatic rebound resulting from melting glaciers may also impact volcanics, by changing the pressures, and so lowering the melting point if the rocks. "The average melting rate is increased by about 30 times its steady state value when a 2-km-thick ice sheet melts in 1000 years." In Iceland, the melting of the glaciers at the end of the last ice age correlates with a 30-fold increase in eruption rate. (Source)in