Climate of Arid Landscapes What are deserts 1

Climate of Arid Landscapes What are deserts? ¬ 1. Low & Mid-latitude Deserts ¬ 2. Low & Mid-latitude Steppes ¬ 3. Applied: Living in the Sahel ¬ 4. Desertification Joshua Tree Desert Preserve Namib Desert The only deserts in the world that have a reliable source of water are those that lie alongside a cold ocean current

Map of Arid Lands B climates are clearly the most extensive climate over land (35%) Koeppen Key B: PE > P W: P < ½ PE h: MAT >64º F K: MAT < 64º F Consider: Can h deserts receive > precip than k deserts and still be drier?

General Characteristics of BW 1. Between 15º & 30º N/S Subtropical H predominate 2. West coast strong E subsidence Great Basin Exceptions to general Characteristics 1. Great Basin/Patagonia (40º) Rain Shadow 2. Taklamakan/Turkestan/Gobi moisture-bearing air mass 3. N. East Africa & Somalia Asia excludes maritime air Taklamakan highlands & S. Asian monsoon H L Weak (E) /strong (W) subsidence Summer

Applied Regional Climatology: Living in the Sahel When over 100, 000 people in the Sahel died , the human consequences of climate change became a reality. 3. Adaptation Acclimatization Human response to heat 1. The human thermostat 2. Dehydration (15 -20% of body wt. ) - low body mass, long limbs, long nose(humidify air) - > in blood and sweat, < heat rate The Sahel is a region of & in transition (BSh) Animal adaptation, Thorny Devil Loose cloths on a Tuareg, Algeria

Is the Sahel Experiencing Desertification Advancing Deserts 1. 50 m. ac. of lost productivity/yr (1970’s) or 30 mi/yr 2. Causes of desertification - heavy settlement (>30 million) - drought/southward shift in the ITCZ - overgrazing = > albedo = absorb < heat = < convection = stay desert - less evapotranspiration - fluctuations in global climate - rainfall & revegetation - tied to sea surface temperatures - Sun spot cycle? ? No one answer Basal Zone Metabolic reserve

Desertification-Climate Feedback

Is the Sahel Experiencing Desertification Agriculture: peanut production & field abandonment The Many Human Causes of Desertification Grazing, especially goats Deforestation, fuel gathering in Mali Fossil water removal Ground water removal, Centerpivot irrigation, Libya More wells = more desertification, Niger Barren circles/ year around grazing

Is the Sahel Experiencing Desertification Center-pivot Armored soil Wind erosion

Applied Regional Climatology: Living in the Sahel Desertification in Decline Between 1984 and 1991 the area of desert has declined by 270, 000 sq mi