EarthTrends (http://earthtrends.wri.org) Searchable Database Results
Provided by the World Resources Institute (http://www.wri.org)
"Forests, Grasslands and Drylands -- Dryland Extent: Semi-arid area, average"

"Units: 1000 hectares"

,,1951,
World
"World","",2240060.3,

,,1951,
Region/Classification
"Asia (excluding Middle East)","",455912.7,
"Central America & Caribbean","",72448.9,
"Europe","",196740.4,
"Middle East & North Africa","",182029.9,
"North America","",317902.5,
"Oceania","",306315.3,
"South America","",226509.1,
"Sub-Saharan Africa","",477370.2,
"Developed Countries","",1074624.9,
"Developing Countries","",1160604.1,

,,1951,
Country
"Afghanistan","AFG",29278.2,
"Albania","ALB",0.0,
"Algeria","DZA",11095.8,
"Andorra","AND",0.0,
"Angola","AGO",9731.1,
"Argentina","ARG",87347.3,
"Armenia","ARM",568.5,
"Australia","AUS",306262.0,
"Austria","AUT",0.0,
"Azerbaijan","AZE",2924.1,
"Bahamas","BHS",0.0,
"Bangladesh","BGD",0.0,
"Belgium","BEL",0.0,
"Belize","BLZ",0.0,
"Benin","BEN",1682.2,
"Bhutan","BTN",0.0,
"Bosnia and Herzegovina","BIH",0.0,
"Botswana","BWA",48402.2,
"Brazil","BRA",80049.7,
"Brunei Darussalam","BRN",0.0,
"Bulgaria","BGR",215.0,
"Burkina Faso","BFA",21650.2,
"Burundi","BDI",0.0,
"Cambodia","KHM",0.0,
"Cameroon","CMR",3267.6,
"Canada","CAN",27424.5,
"Cape Verde","CPV",0.0,
"Central African Rep","CAF",2161.3,
"Chad","TCD",35780.4,
"Chile","CHL",8083.9,
"China","CHN",87245.9,
"Colombia","COL",4640.0,
"Comoros","COM",0.0,
"Congo","COG",0.0,
"Congo, Dem Rep","COD",0.0,
"Costa Rica","CRI",0.0,
"Croatia","HRV",0.0,
"Cuba","CUB",185.4,
"Cyprus","CYP",748.8,
"Czech Rep","CZE",0.0,
"Denmark","DNK",0.0,
"Djibouti","DJI",86.5,
"Dominican Rep","DOM",19.2,
"Ecuador","ECU",3846.4,
"Egypt","EGY",774.6,
"El Salvador","SLV",0.0,
"Equatorial Guinea","GNQ",0.0,
"Eritrea","ERI",1103.5,
"Estonia","EST",0.0,
"Ethiopia","ETH",27798.2,
"Fiji","FJI",0.0,
"Finland","FIN",0.0,
"France","FRA",37.7,
"French Guiana","GUF",0.0,
"Gabon","GAB",0.0,
"Gambia","GMB",159.7,
"Georgia","GEO",327.7,
"Germany","DEU",0.0,
"Ghana","GHA",7388.4,
"Greece","GRC",3103.6,
"Greenland","GRL",0.0,
"Guatemala","GTM",0.0,
"Guinea","GIN",0.0,
"Guinea-Bissau","GNB",0.0,
"Guyana","GUY",0.0,
"Haiti","HTI",0.0,
"Honduras","HND",0.0,
"Hong Kong","HKG",0.0,
"Hungary","HUN",0.0,
"India","IND",92364.7,
"Indonesia","IDN",0.0,
"Iran, Islamic Rep","IRN",56890.1,
"Iraq","IRQ",9280.2,
"Ireland","IRL",0.0,
"Israel","ISR",1373.2,
"Italy","ITA",2853.9,
"Jamaica","JAM",130.4,
"Japan","JPN",0.0,
"Jordan","JOR",3295.9,
"Kazakhstan","KAZ",180133.0,
"Kenya","KEN",20927.2,
"Korea, Dem People's Rep","PRK",0.0,
"Korea, Rep","KOR",0.0,
"Kuwait","KWT",0.0,
"Kyrgyzstan","KGZ",7768.9,
"Lao People's Dem Rep","LAO",0.0,
"Latvia","LVA",0.0,
"Lebanon","LBN",224.4,
"Lesotho","LSO",0.0,
"Liberia","LBR",0.0,
"Libyan Arab Jamahiriya","LBY",3425.9,
"Liechtenstein","LIE",0.0,
"Lithuania","LTU",0.0,
"Luxembourg","LUX",0.0,
"Macau","MAC",0.0,
"Macedonia, FYR","MKD",0.0,
"Madagascar","MDG",8286.7,
"Malawi","MWI",0.0,
"Malaysia","MYS",0.0,
"Mali","MLI",26156.3,
"Mauritania","MRT",2072.9,
"Mauritius","MUS",0.0,
"Mexico","MEX",72106.2,
"Moldova, Rep","MDA",401.8,
"Mongolia","MNG",53022.2,
"Morocco","MAR",19161.5,
"Mozambique","MOZ",6898.0,
"Namibia","NAM",44995.5,
"Nepal","NPL",0.0,
"Netherlands","NLD",0.0,
"New Caledonia","NCL",0.0,
"New Zealand","NZL",0.0,
"Nicaragua","NIC",0.0,
"Niger","NER",24057.8,
"Nigeria","NGA",24909.6,
"Norway","NOR",0.0,
"Oman","OMN",0.0,
"Pakistan","PAK",11311.8,
"Palestinian Territories","",36.1,
"Panama","PAN",0.0,
"Papua New Guinea","PNG",53.3,
"Paraguay","PRY",13389.6,
"Peru","PER",10188.7,
"Philippines","PHL",0.0,
"Poland","POL",0.0,
"Portugal","PRT",562.1,
"Puerto Rico","PRI",0.0,
"Qatar","QAT",0.0,
"Réunion","REU",0.0,
"Romania","ROU",1838.1,
"Russian Federation","RUS",159955.0,
"Rwanda","RWA",0.0,
"San Marino","SMR",0.0,
"Sao Tome & Principe","STP",63.2,
"Saudi Arabia","SAU",8.3,
"Senegal","SEN",8854.7,
"Sierra Leone","SLE",0.0,
"Singapore","SGP",0.0,
"Slovakia","SVK",0.0,
"Slovenia","SVN",0.0,
"Solomon Islands","SLB",0.0,
"Somalia","SOM",11869.5,
"South Africa","ZAF",40636.4,
"Spain","ESP",19359.8,
"Sri Lanka","LKA",257.7,
"Sudan","SDN",82354.3,
"Suriname","SUR",0.0,
"Swaziland","SWZ",250.7,
"Sweden","SWE",0.0,
"Switzerland","CHE",0.0,
"Syrian Arab Rep","SYR",7817.3,
"Taiwan","TWN",0.0,
"Tajikistan","TJK",3390.6,
"Thailand","THA",0.0,
"Togo","TGO",564.1,
"Trinidad and Tobago","TTO",7.7,
"Tunisia","TUN",3386.6,
"Turkey","TUR",35233.0,
"Turkmenistan","TKM",1672.6,
"Uganda","UGA",3411.5,
"Ukraine","UKR",8413.4,
"United Arab Emirates","ARE",0.0,
"United Kingdom","GBR",0.0,
"United States","USA",290478.0,
"Uruguay","URY",0.0,
"Uzbekistan","UZB",14925.0,
"Vanuatu","VUT",0.0,
"Venezuela","VEN",18963.5,
"Viet Nam","VNM",0.0,
"Western Sahara","",0.0,
"Yemen","YEM",0.0,
"Zambia","ZMB",541.9,
"Zimbabwe","ZWE",11308.6,

Footnotes
No footnotes

Source
"UNEP/GRID.  United Nations Environment Program/Global Resource Information Database.  1991.  Global digital data sets for land degradation studies: a GIS approach.  Prepared by U. Deichmann and L. Eklundh.  GRID Case Study Series No. 4. UNEP/GEMS and GRID.  Nairobi, Kenya."


Technical Notes
"Definition:"
"Semi-arid area land area is the total terrestrial area falling within the semi-arid aridity zone, one of three zones that is used to define dryland area (the arid, semi-arid, and dry sub-humid zones).  The aridity zones are defined by the ratio of precipitation to potential evapotranspiration.  See the methodology section for more detail"
""
"This definition of drylands has been adopted by the United Nations Convention to Combat Desertification (CCD) to describe lands where problems with land degradation should be focused and where methods for attaining sustainable development should be promoted.  The world is divided into these six aridity zones based on the ratio of mean annual precipitation to mean annual potential evapotranspiration, described in more detail in the Methodology section below. "
""
"Years Covered and Frequency of Update:"
"The aridity zone boundaries used to derive the country-level totals were prepared under the auspices of the United Nations Environment Programme (UNEP) in 1991.  "
""
"Methodology:"
"The United Nations Convention to Combat Desertification (CCD) uses aridity zones to define drylands of concern to the Convention.  The CCD includes three aridity zones – arid, semi-arid, and dry sub-humid – in its definition of drylands. "
""
"In total, the world is divided into six aridity zones: hyper-arid, arid, semi-arid, dry sub-humid, moist sub-humid, and humid.  Each zone is defined by a ratio (or aridity index) of mean annual precipitation (PPT) to mean annual potential evapotranspiration (PET).  PET is the “amount of moisture that, if it were available, would be removed from a given land area by evaporation and transpiration"", and is empirically derived from data on temperature and length of daylight.  Drylands of concern to the CCD include those lands with an aridity index between .05 and .65 (excluding polar and sub-polar regions).  Ratios of less than .05 indicate hyperarid zones, or true deserts, which are not included in the Convention’s definition of drylands because of their naturally very low biological productivity.  Ratios of .65 or greater identify humid zones.   "
""
"The ratios of PPT to PET for each aridity zone are as follows: "
"Hyperarid:  "
"Arid:  0.05 to 0.20"
"Semi-arid:  0.20 to 0.5"
"Dry Sub-humid: 0.5 to 0.65"
"Moist Sub-humid: 0.65 to 1.0"
"Humid: >1"
""
"UNEP used climate surfaces developed by the East Anglica University Climatic Research Centre to define aridity zone boundaries for the globe.  The resolution of the climatic surfaces was 0.5 decimal degrees, or about 50 km.  The climate surfaces were used to create PPT, PET, and the six aridity zones for the world.  The amount of land within each aridity zone for individual countries was calculated by WRI using GIS.  "
""
"Data Reliability and Cautionary Notes:"
"Factors to consider when evaluating the reliability of the aridity zone boundaries and land area totals within the aridity zones include the relatively low resolution of the data and the limited number of field observations used to derive the climate datasets.  It also is important to note that actual boundaries between aridity zones on the ground are not abrupt or static making delineated borders somewhat artificial.  The data therefore, should be considered useful as a general indicator of the amount of dryland within each country, rather than as an exact depiction of the climatic situation on the ground. "
""
"Alternative methods for measuring extent of dryland area include use of soil moisture and agricultural production systems, although these methods also may be subject to problems such as low resolution data, limited field observations, and subjectivity when delineating exact boundaries on the ground."
""