Atmospheric rivers (ARs) are critical to the hydrological cycle of the western United States with both favorable and formidable impacts to society based on their landfalling characteristics. In this study, we provide a first-of-its-kind evaluation of how landfalling ARs may respond to several stabilized warming scenarios. To do this we combine a recently developed AR detection workflow with an ensemble of uniform high-resolution (0.25°) Community Earth System Model simulations designed to facilitate detection and attribution of extreme events with global warming. These simulations include a world that might have been in the absence of anthropogenic warming (+0^◦C), a world that corresponds to present day warming (+0.85^◦C), and several future worlds corresponding to +1.5^◦C, +2^◦C and +3^◦C global warming. We show that warming increases the number of water management relevant landfalling ARs from 19.1 ARs per year at +0^◦C to 23.6 ARs per year at +3^◦C. Additionally, this warming intensifies the amount of water transported by landfalling ARs resulting in a decrease in the fraction of ARs that are “mostly to primarily beneficial” to water resource management (i.e., 91% of ARs at +0^◦C to 78% at +3^◦C) and an increase in the fraction of ARs that are “mostly or primarily hazardous” to water resource management (i.e., 2% of ARs at +0^◦C to 8% at +3^◦C). Shifts in AR character also have important ramifications on flood damages, whereby for every +1^◦C of additional warming from present conditions annual average flood damages increase by ~$1 billion. These findings highlight the pragmatic implications of climate mitigation aimed at limiting global warming to under +2^◦C.

大气河流（ARs）对于美国西部的水文循环至关重要，根据其着陆特征，对社会既有有利的影响，也有巨大的影响。在这项研究中，我们对登陆的AR如何响应几种稳定的变暖情景进行了首次评估。为此，我们将最新开发的AR检测工作流程与统一的高分辨率（0.25 °）社区地球系统模型仿真集成在一起，旨在促进全球变暖对极端事件的检测和归因。这些模拟包括一个可能没有人为变暖（+0 ^° C）的世界，一个对应于当前变暖（+0.85 ^° C）的世界。C），以及与+1.5 ^° C，+ 2 ^° C和+3 ^° C全球变暖相对应的几个未来世界。我们发现，全球变暖增加了水资源管理的相关登陆的AR从每年19.1人工鱼礁人数为+ 0 ^◦每年C至23.6人工鱼礁在+3 ^◦ C.此外，这种变暖加剧的水中导致登陆人工鱼礁运输量降低是AR的级分“主要是为了主要有利”，以水资源管理（即，在0 AR的91％^◦ C至78％在3 ^◦ C），并增加了其是AR的部分“对水资源管理有“大部分或主要危险”（即，+ 0 ^° C时AR的2％，+ 3时8％^◦C）。在AR角色的变化也对洪水灾害的重要的影响，因此对于每+1 ^◦从目前条件c额外变暖的年均洪水损失增加约1十亿$。这些发现突显了旨在将全球变暖限制在+2 ^° C以下的缓解气候变化的实际意义。