How much area in the world is under SemiArid climate? I am studying the L.C. King's "Normal Cycle of Erosion". 

Apparently, he suggests that Davis was incorrect to have assumed Temperate Humid conditions as "normal conditions" of the world when suggesting his (Davisain) Normal Cycle of Erosion. 

King goes on to suggest that it should be "semi-arid" conditions instead which should be assumed to be "normal conditions" (representative of the world's climate) and hence, suggested his (King's) "Normal Cycle of Erosion".

So my questions are:


How did L.C. King define SemiArid climate?
How much area in the world is under SemiArid climate as defined by L.C. King?
How much area in the world is under Temperate climate?






P.S.: I suppose if a figure isn't available for Temperate/SemiArid climate, a figure for the 6 Temperate Biomes and the 3 SemiArid Biomes would also do the trick...


6 Temperate Biomes: Warm Temperate Eastern Margin (China/Gulf Type), Warm Temperate Continental (Steppe Grasslands Type), Warm Temperate Western Margin (Mediterranean type), Cool Temperate Eastern Margin (Laurentian type), Cool Temperate Continental (Taiga type), Cool Temperate Western Margin (British type).
3 Semi Arid Biomes: Warm Temperate Continental (Steppe Grasslands Type), Warm Temperate Western Margin (Mediterranean type), Tropical Grasslands (Savanna type)
According to this link is 14% for Köppen classification.

The precise cite is:

"BS - dry semiarid (steppe). Is a grassland climate that covers 14% of the Earth's land surface."