《Proceedings of the National Academy of Sciences》杂志刊登“美国西南地区未来干旱灾害及21世纪早期干旱的水文模拟

作者：Daniel R. Cayan, Tapash Das, David W. Pierce, Tim P. Barnett, Mary Tyree, and Alexander Gershunov

刊物：PNAS  2010年12月，107卷，50期，页码：21271-21276

关键词：气候变化；区域模型模拟；可持续性；水资源

摘要：近期美国西南部地区经历了一场干旱，这对该渔区人口与自然系统用水的可持续发展造成了挑战。在科罗拉多流域，21世纪早期是近一个世纪以来该流域所经历的最严重的干旱，同时在历史上任何给定时代同等旱情的发生概率仅为60%。然而，运用IPCC第四次评估报告中模拟气候变化降尺度后的数据来驱动水文模型模拟，结果表明该区域将变得更干且会经历更严重的干旱灾害。在21世纪后半叶，水文模型模拟出了非常严重的干旱情况，特别是在科罗拉多流域，这种干旱是通过土壤水分含量的异常或其他水文条件来确定的。在历史记载中，多数模拟出来的干旱都会持续若干年。历史记载中，土壤水分消耗的持续时间从4年到10年不等，但在对21世纪的模拟中，一些干旱会持续超过12年。在21世纪早期所观测到的夏季气温都较高，这一特征在模拟中也很明显。这些未来的干旱受全球性的气温上升而加剧，并引起春季积雪的减少以及晚春、夏季土壤水分的减少。随着气温的持续上升，土壤水分含量减少总量将超过历史水平，模型模拟的结果表明，在美国西南部的部分区域，其供水可持续性将面临严峻的挑战。

Future dryness in the southwest US and the hydrology of the early 21st century drought

Authors: Daniel R. Cayan, Tapash Das, David W. Pierce, Tim P. Barnett, Mary Tyree, and Alexander Gershunov

Journal: PNAS，2010,12，page21271-21276

Key words: climate change regional modeling sustainability water resources

Abstract: Recently the Southwest has experienced a spate of dryness, which presents a challenge to the sustainability of current water use by human and natural systems in the region. In the Colorado River Basin, the early 21st century drought has been the most extreme in over a century of Colorado River flows, and might occur in any given century with probability of only 60%. However, hydrological model runs from downscaled Intergovernmental Panel on Climate Change Fourth Assessment climate change simulations suggest that the region is likely to become drier and experience more severe droughts than this. In the latter half of the 21st century the models produced considerably greater drought activity, particularly in the Colorado River Basin, as judged from soil moisture anomalies and other hydrological measures. As in the historical record, most of the simulated extreme droughts build up and persist over many years. Durations of depleted soil moisture over the historical record ranged from 4 to 10 years, but in the 21st century simulations, some of the dry events persisted for 12 years or more. Summers during the observed early 21st century drought were remarkably warm, a feature also evident in many simulated droughts of the 21st century. These severe future droughts are aggravated by enhanced, globally warmed temperatures that reduce spring snowpack and late spring and summer soil moisture. As the climate continues to warm and soil moisture deficits accumulate beyond historical levels, the model simulations suggest that sustaining water supplies in parts of the Southwest will be a challenge.

原文链接：http://www.pnas.org/content/107/50/21271.short