气候变化领域集成服务门户(CCPortal): Illuminating Snow Droughts: The Future of Western United States Snowpack in the SPEAR Large Ensemble

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DOI	10.1029/2023JD039754
	Illuminating Snow Droughts: The Future of Western United States Snowpack in the SPEAR Large Ensemble
	Schmitt, Julian; Tseng, Kai-Chih; Hughes, Mimi; Johnson, Nathaniel C.
发表日期	2024
ISSN	2169-897X
EISSN	2169-8996
起始页码	129
结束页码	10
卷号	129 期号:10
英文摘要	Seasonal snowpack in the Western United States (WUS) is vital for meeting summer hydrological demands, reducing the intensity and frequency of wildfires, and supporting snow-tourism economies. While the frequency and severity of snow droughts (SD), that is, anomalously low snowpacks, are expected to increase under continued global warming, the uncertainty from internal climate variability remains challenging to quantify with observations alone. Using a 30-member large ensemble from a state-of-the-art global climate model, the Seamless System for Prediction and EArth System Research (SPEAR), and an observations-based data set, we find WUS SD changes are already significant. By 2100, SPEAR projects SDs to be nearly 9 times more frequent under shared socioeconomic pathway 5-8.5 (SSP5-8.5) and 5 times more frequent under SSP2-4.5, compared to a 1921-2011 average. By investigating the influence of the two primary drivers of SD, temperature and precipitation amount, we find the average WUS SD will become warmer and wetter. To assess how these changes affect future summer water availability, we track late winter and spring snowpack across WUS watersheds, finding differences in the onset time of a no-snow threshold between regions and large internal variability within the ensemble that are both on the order of decades. We attribute the inter-regional variability to differences in the regions' mean winter temperature and the intra-regional variability to irreducible internal climate variability which is not well-explained by temperature variations alone. Despite strong scenario forcing, internal climate variability will continue to drive variations in SD and no-snow conditions through 2100. Snow drought (SD) occurs when there is significantly less snow on the ground than normal. SDs can intensify water shortages, accelerate wildfires, and harm snow-based tourism economies. For the Western United States, whose water supply is already limited, a recent increase in snow drought frequency is particularly concerning. Here, we use observational data and a new climate model to examine snow drought changes across the region between 1921 and 2100. We find SDs are already more common and could increase almost nine times under a high emissions scenario or five times under moderate emissions cuts by 2100. To better understand the increase, we tracked the evolution of the two main snow drought drivers: warmer temperatures and decreased precipitation. We find the average snow drought will become warmer and wetter, indicating warming temperatures are driving the increase. As the model consists of multiple simulations of future climate, or ensemble members, that differ only in the realization of random climate variability, we can determine when Western regions are expected to lose most of their spring snowpack. We find that loss timing varies dramatically between regions and ensemble members, suggesting random climate variability will shape the West's future water availability. Excluding the Pacific Northwest, observed increases of Western U.S. severe snow drought by 4%-46% are supported by the Seamless System for Prediction and EArth System Research (SPEAR) climate model 21st century increases in Western U.S. severe snow drought in SPEAR are driven by rising temperatures and not decreased precipitation By 2100 under SSP5-8.5, SPEAR projects persistent Western U.S. spring no-snow with timing sensitive to internal climate variability
英文关键词	western US hydroclimate; snow drought; global climate model; climate extremes; climate change; internal climate variability
语种	英语
WOS研究方向	Meteorology & Atmospheric Sciences
WOS类目	Meteorology & Atmospheric Sciences
WOS记录号	WOS:001230704900001
来源期刊	JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/296336
作者单位	California Institute of Technology; National Oceanic Atmospheric Admin (NOAA) - USA; Princeton University; National Taiwan University
推荐引用方式 GB/T 7714	Schmitt, Julian,Tseng, Kai-Chih,Hughes, Mimi,et al. Illuminating Snow Droughts: The Future of Western United States Snowpack in the SPEAR Large Ensemble[J],2024,129(10).
APA	Schmitt, Julian,Tseng, Kai-Chih,Hughes, Mimi,&Johnson, Nathaniel C..(2024).Illuminating Snow Droughts: The Future of Western United States Snowpack in the SPEAR Large Ensemble.JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES,129(10).
MLA	Schmitt, Julian,et al."Illuminating Snow Droughts: The Future of Western United States Snowpack in the SPEAR Large Ensemble".JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 129.10(2024).