Evaporating futures Drought and warming have been shrinking Colorado River flow for many years. Milly and Dunne used a hydrologic model and historical observations to show that this decrease is due mainly to increased evapotranspiration caused by a reduction of albedo from snow loss and the associated rise in the absorption of solar radiation (see the Perspective by Hobbins and Barsugli). This drying will be greater than the projected precipitation increases expected from climate warming, increasing the risk of severe water shortages in an already vulnerable region. Science, this issue p. 1252; see also p. 1192 The Colorado River Basin is losing progressively more water to evaporation, owing to the disappearance of snow. The sensitivity of river discharge to climate-system warming is highly uncertain, and the processes that govern river discharge are poorly understood, which impedes climate-change adaptation. A prominent exemplar is the Colorado River, where meteorological drought and warming are shrinking a water resource that supports more than 1 trillion dollars of economic activity per year. A Monte Carlo simulation with a radiation-aware hydrologic model resolves the longstanding, wide disparity in sensitivity estimates and reveals the controlling physical processes. We estimate that annual mean discharge has been decreasing by 9.3% per degree Celsius of warming because of increased evapotranspiration, mainly driven by snow loss and a consequent decrease in reflection of solar radiation. Projected precipitation increases likely will not suffice to fully counter the robust, thermodynamically induced drying. Thus, an increasing risk of severe water shortages is expected.

中文翻译：

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科罗拉多河流量减少，因为变暖驱动的反射雪的损失促进了蒸发

蒸发期货多年来，干旱和变暖一直在减少科罗拉多河的流量。Milly 和 Dunne 使用水文模型和历史观察结果表明，这种减少主要是由于雪损失引起的反照率减少以及相关的太阳辐射吸收增加引起的蒸散量增加（参见 Hobbins 和 Barsugli 的观点）。这种干燥将大于气候变暖导致的预计降水量增加，从而增加本已脆弱地区严重缺水的风险。科学，这个问题 p。1252; 另见第 1192 由于雪的消失，科罗拉多河流域的水分逐渐蒸发。河流流量对气候系统变暖的敏感性高度不确定，并且控制河流排放的过程知之甚少，这阻碍了气候变化的适应。一个突出的例子是科罗拉多河，那里的气象干旱和变暖正在减少每年支持超过 1 万亿美元经济活动的水资源。带有辐射感知水文模型的蒙特卡罗模拟解决了敏感性估计中长期存在的广泛差异，并揭示了控制物理过程。我们估计，由于蒸发蒸腾量增加，主要是由于积雪减少和随之而来的太阳辐射反射减少，因此每年平均排放量每升高 1 摄氏度就会减少 9.3%。预计的降水增加可能不足以完全抵消热力学引起的强烈干燥。因此，