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2. GEO for World Deserts Chapter 1 proposal

3. Global atmospheric circulation and the distribution of deserts

6. Ocean upwellings and westerly coastal deserts

8. tidal mixing upwelling California current Tidal flow upwelling Coriolis deflection

12. Rain-shadow deserts

15. Pleistocene glaciations and desert biodiversity

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 world’s 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. 3 2 1 a 0 SOI -1 -2 -3 -4 4 b 2 Anomaly (°C) 0 -2 -4 1985 1990 1995 2000 periods of extraordinary rainfall

26. El Niño conditions La Niña conditions r = 0.53 300 100 rainfall anomaly (mm) -3 -2 -1 1 2 -100 -300 SOI

27. May 1998

28. September 2003

30. moisture time time time environmental pulses averagers trackers

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.

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.

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 m3/kg grano cosechado Cultivo de alfalfa: 1.6 m3/kg forraje cosechado Carne de vacuno: 31 m3/kg de carne

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 m3 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 0.046 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 m3 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: 7.4  106 Joule/kg cosechado (aprox. 0.34 L gasolina/kg maíz) Cultivo de alfalfa: 4.6  106 Joule/kg cosechado (aprox. 0.21 L gasolina/kg alfalfa) Carne de vacuno: 91.9  106 Joule/kg de carne (aprox. 4.21 L gasolina/kg carne)

48. Los límites de la desalinización del agua de mar Presión osmótica del agua de mar: 2.75 MPa Trabajo teórico para desalinizar 1 m3: 2.75 MJ Trabajo real para desalinizar 1 m3: 27 MJ = 7.5 kW-h

49. Coastal ecosystems as water users