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Résumé :
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Simply put, "No water, no life." But how is our supply of freshwater maintained? Scientist Kandel explains the earth's elaborate and essential-to-life water cycle in a suitably fluid and mesmerizing narrative, beginning cosmologically with the birth of the solar system and an analysis of various theories as to where the earth's water, weighing in at "over a billion billion tons," originated. Kandel traces the balance of salt water and freshwater to ice and snow over the course of the earth's volatile geological history, pausing to consider past mass extinctions and our current precipitous loss of life-forms. He then cogently explains the awesome, truly beautiful dynamics of the tides, deep-water ocean currents, and every phase of the water cycle, which maintains the crucial balance between evaporation and condensation. "Life on the land depends on water from the sky," Kandel reminds readers, as he assiduously catalogs every threat to our precious water supply, from pollution to climate change to deforestation to unwise water management to the tricky convolutions of "hydropolitics." The more we understand about the water cycle, the better our chances of ensuring its continuance. Donna Seaman
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