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(click to start). GEO for World Deserts Chapter 1 proposal.

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Presentación del tema: "(click to start). GEO for World Deserts Chapter 1 proposal."— Transcripción de la presentación:

1 (click to start)

2 GEO for World Deserts Chapter 1 proposal

3 Global atmospheric circulation and the distribution of deserts

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6 Ocean upwellings and westerly coastal deserts

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8 California current Coriolis deflection upwelling Tidal flow upwelling tidal mixing

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12 Rain-shadow deserts

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15 Pleistocene glaciations and desert biodiversity

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18 Deserts and Pleistocene Relicts

19 Fragility of World Deserts In spite of their apparent barrenness, the deserts of the world harbor unique and rare biotas with impressive biological adaptations. The fragmented evolutionary history of the deserts of the world has been the driving force of their biological rarity, of adaptation to local conditions, of specialization to isolated environments. As a result of evolution in isolation from each other, the worlds deserts have high levels of endemism and harbour rare and unique life forms, a fact that makes them ecologically fragile and highly vulnerable to biological extinction.

20 Cycles, anomalies, and teleconnections

21 The nurse-plant cycle

22 periods of extraordinary rainfall SOI Anomaly (°C) a b

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26 r = SOI rainfall anomaly (mm) El Niño conditions La Niña conditions

27 May 1998

28 September 2003

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30 time trackers averagers time moisture environmental pulses

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36 Deserts and agriculture Because desert ephemerals grow fast and produce abundant seed in just a few weeks, it comes as no surprise that the earliest archaeological records of agriculture come from dryland regions and that the first domesticated crops evolved from desert annuals. Indeed, the first records of cultivated wheat and barley (two desert ephemerals) come from the Fertile Crescent of the Middle-East some 7–9 thousand years ago.

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39 Deserts and agriculture Similarly, in the American Continent the first agricultural records come from the Tehuacán Valley in southern Mexico, a hot rain-shadow tropical desert where corn, amaranth and squash (all annual, drought-tolerant, fast growers) were first domesticated some 6 thousand years ago. To a large extent, deserts have been the cradle of agriculture.

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42 Deserts and water use

43 Eficiencia ecológica del uso del agua en cuencas de riego del norte de México Cultivo de maíz: 2.5 m 3 /kg grano cosechado Cultivo de alfalfa: 1.6 m 3 /kg forraje cosechado Carne de vacuno: 31 m 3 /kg de carne

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45 Conversión de eficiencia ecológica a eficiencia energética del uso del agua a.- Elevar 1 L de agua una altura de 1 metro consume 9.8 Joule. b.- Por lo tanto, elevar 1 m 3 de agua desde un acuífero de 100 metros de profundidad, consume aprox. 1 MJoule. c.- Un MJoule es igual a 0.28 kW-h, y es igual a la energía calórica contenida en L de gasolina. d.- Considerando la fricción en las tuberías y la ineficiencia energética de los motores y las bombas, se necesitan aprox. 0.1 L de gasolina para elevar 1 m 3 de agua desde 100 metros de profundidad, o se deben gastar 0.28 kW-h.

46 Eficiencia energética del uso del agua en cuencas de riego del norte de México Cultivo de maíz: Joule/kg cosechado (aprox L gasolina/kg maíz) Cultivo de alfalfa: Joule/kg cosechado (aprox L gasolina/kg alfalfa) Carne de vacuno: Joule/kg de carne (aprox L gasolina/kg carne)

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48 Los límites de la desalinización del agua de mar Presión osmótica del agua de mar: 2.75 MPa Trabajo teórico para desalinizar 1 m 3 : 2.75 MJ Trabajo real para desalinizar 1 m 3 : 27 MJ = 7.5 kW-h

49 Coastal ecosystems as water users

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51 Chapter 1: Ecology and evolution of the worlds deserts a. Global distribution of deserts The desert biome, general climatic and geographic conditions Latitudinal desert belts The effect of coastal upwellings on desert evolution Rain-shadows and tropical arid zones

52 Chapter 1: Ecology and evolution of the worlds deserts b. Evolution, history and biogeography Glacial periods and the evolution of desert biota The expansion of deserts during the Holocene Mountain sky-islands and Pleistocene relicts The evolution and development of pastoralism

53 Chapter 1: Ecology and evolution of the worlds deserts c. Biological adaptation to aridity Cycles of abundance and scarcity Life-forms and adaptations of plants and animals to aridity Species interactions: pollinators, seed dispersers, facilitation Deserts and agriculture

54 Chapter 1: Ecology and evolution of the worlds deserts d. Global environmental dynamics and desert ecosystems Ocean/atmospheric/land coupling phenomena Long-term cycles; El Niño anomalies Desert dust in the global atmosphere and its consequences Desertification, albedo changes, and global change

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