# 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:

1. How did L.C. King define SemiArid climate?
2. How much area in the world is under SemiArid climate as defined by L.C. King?
3. 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)
• Please, could you provide more details about what exactly you are asking? – arkaia Nov 9 '16 at 18:07
• @aretxabaleta: Right. I've updated the question with the context of my study. – EarthLearner Nov 13 '16 at 1:47
• What is your definition of a semi-arid climate here? Without that, I'm not sure this question is answerable, as it would depend upon the definition. – hichris123 Nov 16 '16 at 22:18
• @hichris123: Would this criteria do as a definition.."(1) areas where annual evapotranspiration exceeding annual precipitation; (2) should be marked by either grassland or park-landscape vegetation; and (3) should be areas in either temperate or tropical latitudes."..?? – EarthLearner Nov 18 '16 at 5:06
• @hichris123: Just for curiosity sake...how did L. C. King define a semi-arid region when propounding his "Normal Cycle" of erosion? – EarthLearner Nov 18 '16 at 5:08

After looking at the OP's definition of the biomes that are semi-arid and temperate, I decided to compare them to the biomes in WWF's Wildfinder and sum the area total. The WWF biomes don't really match up with the biomes defined by the OP (and originally by LC King, apparently, though I haven't read anything of his), but they at least give an alternative estimate.

For the Semi-Arid Biomes, I have:

For a total of 31.1 million km$^2$ or 6.1% of the earth's surface.

For Temperate, there are two listed above plus:

For a grand total of 43.8 million km$^2$ or 8.6% of the Earth's surface.

• Thanks @kingledion! Looking at your estimates along with those of Santiago, I am now pretty confident that under no circumstances can Semi-Arid conditions be prevalent over more than 15-16% of Earth's Land Area. And also, that both Davis and King were grossly incorrect in suggesting a "Normal Cycle" of erosion.. – EarthLearner Nov 18 '16 at 16:02

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."

• A semi-arid climate can be defined in any of several ways, such as <20 inches (<500mm) of rain, or a given threshold of precipitation/evapotranspiration, or vegetation type. Also the global area of 'semi-arid' fluctuates in response to climatic excursions and climate change. – Gordon Stanger Nov 9 '16 at 22:36
• 14% of the Earth's land surface would make around 4% of the Earth total surface. – gerrit Nov 10 '16 at 15:17
• Thanks @Santiago! Looking at your estimates along with those of kingledion, I am now pretty confident that under no circumstances can Semi-Arid conditions be prevalent over more than 15-16% of Earth's Land Area. And also, that both Davis and King were grossly incorrect in suggesting a "Normal Cycle" of erosion.. – EarthLearner Nov 18 '16 at 16:02