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According to an episode of David Attenborough's Planet Earth (only reference I could find is here), a third of Earth's land is covered by deserts. I just cannot believe this.

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Yes, there is plenty of desert, but a third? The Antarctica, Greenland, Canada, Siberia, which are pretty big, are mostly not deserts. Or am I wrong? If this is true, it would mean that population density is pretty high in the other two thirds of the land, as allegedly few people live in deserts.

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    Antartica is a desert. One of the biggest ones, actually. – T. Sar - Reinstate Monica Aug 17 '17 at 22:09
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    Deserts mean the land receive less than 250mm of precipitation a year. Doesn't matter if it hot or cold, sand or snow. – Jimmy M. Aug 17 '17 at 23:27
  • Is the Arctic a desert? it meets the low precipitation criterion and its surface is solid (part all the time and part some of the time) albeit floating – Henry Aug 17 '17 at 23:29
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    Wikipedia en.wikipedia.org/wiki/Desert also has the "one third" estimate, with a USGS reference. – GEdgar Aug 17 '17 at 23:31
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Simple answer: yes

The common misconception is that deserts are hot and dry - when in fact, the definition of a desert is that it is dry and almost completely devoid of vegetation:

From the Wikipedia desert article:

A desert is a region of land that is very dry because it receives low amounts of precipitation (usually in the form of rain but may be snow, mist or fog), often has little coverage by plants, and in which streams dry up unless they are supplied by water from outside the area.[9] Deserts can also be described as areas where more water is lost by evapotranspiration than falls as precipitation.[10] Deserts generally receive less than 250 mm (10 in) of precipitation each year.[9] Semideserts are regions which receive between 250 and 500 mm (10 and 20 in) and when clad in grass, these are known as steppes.

The world has about 150 million square kilometres of land surface area.

The list of deserts larger than 20,000 km2 on Wikipedia totals up to about 48 million square kilometres - with the two largest deserts being the Antarctic and the Arctic at about 14 million square kilometres each.

48/150 is roughly 1/3

  • Is that 14 million km² of land desert area in the Arctic? Greenland is only 2 million km². – gerrit Aug 18 '17 at 9:48
  • @gerrit Land, not ice cap - the northern extremes of Canada, Russia, Norway, Alaska and, of course, Greenland - whatarethe7continents.com/arctic-desert – user2276 Aug 18 '17 at 10:10
  • I know the 7 continents :) Just wonder what areas of Norway, Russia, Canada, and Alaska are a desert by this definition. I've visited a beautiful valley in Northern Norway with <200 mm rainfall (Dividalen). I suppose it would qualify, but this valley is also full of swamps. I suppose a lot of those cold "deserts" are swamps, unlike actually cold deserts like most of Greenland. According to the definition stated, the statement is correct, but I'm not sure if a desert definition including large swamps and lakes is particularly useful. – gerrit Aug 18 '17 at 10:14
  • @gerrit sorry, my first post of the comment missed the link a little - I edited it with a link to specific page with a map if the desert. I guess a swampy valley is like an oasis in the Sahara - microclimates don't negate overall desert climate. – user2276 Aug 18 '17 at 10:25
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    @gerrit: There are swamps is warmish (hot in summer, cold in winter) deserts, too. Here's one instance: en.wikipedia.org/wiki/Stillwater_National_Wildlife_Refuge – jamesqf Aug 19 '17 at 5:59

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