More than sixty percent of the United States is experiencing drought conditions
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专家：超过一半的美国正遭遇数十年来最严重的干旱
目前美国有超过 60% 的地区处于干旱状态，其中超过 20% 被评为极端干旱。 Virginia Tech 的气候学家 Andrew Ellis 表示，因强度和覆盖范围罕见，这次干旱可谓数十年来最严重。他解释了成因、受影响最严重的地区以及可能的缓解前景。
干旱的主要原因是一次非典型的 La Niña，即西赤道太平洋异常冷却。过去的秋冬季里，这一现象在美国南部带来了持续干燥。虽然在 La Niña 年份里，西部、南部大平原和东南部常见干旱，但 Ellis 指出此次不同寻常的一点是太平洋西北部也异常干燥。 La Niña 时风暴通道通常向北移至美加边境附近，导致美国南部缺乏带来降水的风暴动力。另外，气候变暖也在加剧干旱：气温上升会通过蒸散作用增加土壤失水。
最令人担忧的两个地区是 Colorado 和东南部，尤其是 Georgia 和 Florida，这些地方广泛出现极端和严重干旱。更大范围来看，从 deep South 到 mid-Atlantic 的美国东南象限正经历严重干旱，central Rocky Mountains 和高海拔的 Great Plains 地区也在受影响。从 New Jersey 到 Arkansas 的诸州在 La Niña 年份特别容易在秋冬出现干燥，因为它们依赖来自墨西哥湾和东南海岸的水汽——而这一水源在过去六到八个月基本被切断。相对而言，Ohio Valley 在 La Niña 年份通常更湿润，今年也基本没有出现干旱。
在暖季要实现显著的干旱缓解很困难。最常见的缓解往往来自夏末或初秋的热带系统，但这些系统伴随强风和短时强降雨的风险。对于 Rocky Mountains 和高海拔 Great Plains 来说，夏季缓解尤其困难，因为这些地区高度依赖冬季积雪和大尺度冬季风暴系统。东南部和 mid-Atlantic 虽然可能出现由墨西哥湾和大西洋水汽驱动的湿润夏季，但这类降水通常不够持久，难以彻底消除深层干旱。展望秋冬，Ellis 提到有可能出现一次历史性的 El Niño，理论上这可能带来与去年 La Niña 相反的气候格局。
Andrew Ellis 是 Virginia Tech College of Natural Resources and Environment 下 Department of Geography 的教授，研究领域包括气候科学、气象学、降雪变率、干旱监测以及干旱和半干旱地区淡水资源可持续性的评估。
## Expert: More than half of U.S. faces worst drought in decades
More than 60 percent of the United States is currently experiencing drought conditions, with over 20 percent classified as extreme drought. Andrew Ellis, a climatologist at Virginia Tech, described these conditions as among the worst in decades due to the rare combination of intensity and aerial coverage. He explained the causes, the areas most impacted, and the outlook for relief.
The primary cause of the drought is an atypical La Niña condition, which involves the cooling of the western equatorial Pacific Ocean. This phenomenon brought dryness across the southern tier of the United States during the past fall and winter. While dryness is typical in the West, southern Great Plains, and Southeast during La Niña years, Ellis noted this event was unusual because the Pacific Northwest also remained exceptionally dry. During La Niña, the storm track typically moves north along the U.S.-Canadian border, leaving the southern U.S. without the storm dynamics needed for precipitation. Additionally, climate warming is exacerbating the situation by increasing air temperatures, which leads to greater water loss from the soil through evapotranspiration.
The two areas of greatest concern are Colorado and the Southeast, particularly Georgia and Florida, where extreme and exceptional drought conditions are widespread. More broadly, the southeastern quadrant of the U.S. from the deep South to the mid-Atlantic is experiencing deep drought, along with the central Rocky Mountains and high Great Plains regions. States from New Jersey to Arkansas are especially susceptible to fall and winter dryness during La Niña years because they rely on moisture from the Gulf of Mexico and the Southeast coastline, a source that has been largely cut off for the past six to eight months. Conversely, the Ohio Valley tends to be wetter during La Niña years and has remained largely drought-free this year.
Significant drought relief is difficult to achieve during the warmer months. The most significant relief often comes from late summer or early fall tropical systems, though these carry risks of damaging winds and excessive rainfall in short periods. Relief in the Rocky Mountains and high Great Plains is particularly challenging in summer, as those regions depend heavily on winter snowpack and large-scale winter storm systems. While the Southeast and mid-Atlantic can experience wet summer periods driven by Gulf and Atlantic moisture, these events are rarely persistent enough to eliminate a deep drought. Looking beyond summer, Ellis suggested that a historic El Niño event may occur next fall and winter, which could theoretically produce the opposite conditions to this past year's La Niña.
Andrew Ellis is a professor in the Department of Geography within Virginia Tech's College of Natural Resources and Environment. His expertise includes climate science, meteorology, snowfall variability, drought monitoring, and assessing the sustainability of freshwater resources in arid and semi-arid climates.
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当前的干旱图可能具有误导性：预计即将到来的超级厄尔尼诺将在夏末和明年春季为受影响地区带来大量降水，可能消除图中显示的大部分干旱。以 2015–2016 年超级厄尔尼诺为例，当拉尼娜转为厄尔尼诺时，降雨量有可能超过多年平均的两倍以上。
从干旱迅速转为强降雨会带来严重洪水风险。干涸的土壤吸水能力差，容易形成径流，导致受灾区面临更大的水害。实用的防洪建议包括：在秋季来临前检查轮胎花纹深度，车内备好雨具，雨天慢速行驶以防车辆打滑；若发生打滑，应把方向盘朝所需方向并松开油门。此外建议备橡胶靴和手杖，用以探测水深并在流动水中保持平衡。
小麦期货反映出干旱对农业的影响。美国农业部预测，由于平原地区的干旱，美国小麦产量将降至自 1972 年以来的最低水平。随着种植者转向利润更高的作物，小麦种植面积持续减少（下降约 35%），玉米减少约 6%，而大豆种植因对化肥依赖较小而有所增加。
美国西南部正经历至少 1200 年来最严重的长期干旱，但水仍以远低于居民用水价格的水平出售给企业，关键水利基础设施维护却被忽视。西部的水权制度使监管复杂化：水权归属于 150 多年前首次使用它的实体，这一制度加剧了管理难题。
树木减少和城市扩张是干旱的重要且被低估的驱动因素。在北卡罗来纳州罗利附近，过去十年间树冠覆盖率下降了 15% 以上。历史案例（如玛雅文明崩溃）也表明，砍伐森林会导致水资源短缺并最终危及社会稳定。
水循环的中断意味着一些地区年总降水量看似充足，但降水集中在短期内而非全年分布。例如在明尼苏达州，过去常持续到六月或七月的积雪如今反复融化再冻结，无法累积，尽管年降水总量可接受，但夏季仍然干旱。
数据中心的用水量日益令人担忧，尤其是在水权与土地所有权捆绑且难以监管的西部州。部分设施采用闭环冷却系统，但其用水总量相当于小城镇，若含水层消耗速度超过补给速度，就会带来长期可持续性问题。
个人节水措施（如餐厅不主动上水）相比工业和农业用水而言只是分散注意力：无论消除所有个人和数据中心用水，和农业与工业的耗水量相比几乎微不足道。与此相应，讨论指出需要的是基础设施和政策上的变革，而不是象征性的举措。
干旱监测地图虽有用，但也存在局限：包含主观评估成分、对降水事件时点的把握可能不准确，并且不能反映高于平均水平的情况。该地图结合了客观数据与专家解读，因此带有主观性，尽管目前尚无比它更客观的替代方案。
讨论揭示了短期天气事件与长期气候趋势之间的紧张关系，参与者围绕当前干旱究竟是正常气候变动还是人为气候变化展开辩论。通过小麦减产和作物结构变化，农业影响已有明确记录；与此同时，过时的水权制度以及像数据中心这样的新兴行业不断增长的需求，进一步加剧了水资源管理的挑战。对话还强调了干旱测量工具的局限性，并提醒应关注降水的持续时间和分布，而不仅仅是年总量。 • The current drought map may be misleading because a predicted super El Nino is expected to bring heavy precipitation to affected areas by late summer and into next spring, potentially eliminating much of the drought shown. Historical precedent from the 2015-2016 super El Nino shows rainfall can more than double annual averages when La Nina transitions to El Nino.
• Rapid transitions from drought to heavy rainfall create significant flood risks because dried-out soil cannot absorb water effectively, leading to runoff and potential water damage in affected regions.
• Practical flood preparedness advice includes checking tire tread depth before autumn, carrying rain gear in vehicles, driving slowly to avoid hydroplaning, and understanding that if hydroplaning occurs, one should keep wheels pointed in the desired direction and ease off the accelerator. Adding rubber boots and a walking stick for checking water depth and maintaining footing in flowing water is also recommended.
• Wheat futures reflect agricultural impacts of drought, with USDA projecting the smallest US wheat harvest since 1972 due to Plains drought. Wheat acreage continues declining as producers shift to more lucrative crops, with wheat down 35% and corn down 6%, though soybeans appear up due to lesser fertilizer reliance.
• The US Southwest is experiencing its longest period of severe drought in at least 1200 years, yet water continues to be sold to corporations at fractions of what residential rates are, while critical water infrastructure maintenance is neglected. Water rights systems in the West complicate regulation because water belongs to the first entity to have used it over 150 years ago.
• Tree loss and urban sprawl are significant but underappreciated drivers of drought conditions. Near Raleigh, NC, over 15% of tree canopy has been lost in the past decade, and historical examples like the Mayan civilization collapse show how deforestation can lead to water scarcity and civilizational decline.
• Water cycle disruption means some areas receive adequate annual precipitation but in concentrated bursts rather than distributed throughout the year. In Minnesota, snow that once persisted through June or July now melts and refreezes repeatedly without building up, leaving summers dry despite acceptable yearly averages.
• Data center water usage is a growing concern, particularly in western states where water rights are tied to land ownership and difficult to regulate. Some facilities use closed-loop cooling systems, but the scale of water consumption equivalent to small cities raises long-term sustainability questions, especially when aquifers are being depleted faster than they regenerate.
• Individual water conservation measures like restaurants not automatically serving water are distractions from the much larger industrial and agricultural water usage problems. Removing all individual and data center water usage would barely make a dent compared to agricultural and industrial consumption.
• The Drought Monitor map, while useful, has limitations including subjective assessment components, potential inaccuracies in timing precipitation events, and failure to indicate above-average conditions. The map combines objective data with expert interpretation, making it more subjective than fully objective measures, though no more objective alternative exists.
The discussion reveals a tension between short-term weather events and long-term climate trends, with participants debating whether current drought conditions represent normal variability or anthropogenic climate change. Agricultural impacts are clearly documented through declining wheat harvests and shifting crop patterns, while water management challenges are exacerbated by outdated rights systems and growing demand from new industries like data centers. Several commenters emphasize that individual conservation efforts are insignificant compared to industrial and agricultural usage, and that infrastructure and policy changes are needed rather than symbolic gestures. The conversation also touches on the limitations of drought measurement tools and the importance of considering duration and distribution of precipitation rather than just annual totals.