Twenty-first century hydroclimate: A continually changing baseline, with more frequent extremes.
Twenty-first century hydroclimate: A continually changing baseline, with more frequent extremes.
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DOI：
10.1073/pnas.2108124119
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发表时间：
2022-03-22
影响因子：
11.1
通讯作者：
Otto-Bliesner B
中科院分区：
文献类型：
--
作者：
Stevenson S;Coats S;Touma D;Cole J;Lehner F;Fasullo J;Otto-Bliesner B
21世纪的水气候趋势如此之大，以至于在大多数情况下，未来的平均条件将落在我们今天所认为的极端干旱或多雨状态的范围内。使用大型气候模型集合，我们去掉了背景趋势，发现相对于(变化的)基线，干旱和暴雨的风险与20世纪的风险相当相似。因此，通过不断适应长期的背景变化，这些风险可能会被降至最低。然而，即使在消除这一趋势之后，极端潮湿和干旱年份的频率仍在增加，这表明在一个变暖的世界中以可持续的方式管理由水气候驱动的风险将面临越来越困难的挑战。水气候的可变性影响着世界各地的自然和人类系统。特别是，年代际变化和极端降水事件都有重大影响，预计会受到气候变化的强烈影响。从实践的角度来看，这些影响将相对于不断演变的背景气候而感受到。因此，消除潜在的强迫趋势对于评估相对影响是必要的，但到目前为止，大多数气候模型集合的规模很小，因此很难做到这一点。在这里，我们使用在高排放情景下运行的大型集合的档案来确定十年一遇的“特大暴雨”和“特大暴雨”事件--以及较短期的极端降水量--将如何相对于不断变化的基线变化。当趋势保持不变时，平均状态变化占主导地位：事实上，在一些地区，土壤水分变化如此之大，以至于今天被认为是特大暴雨或暴雨的条件预计将变得平均。出现时间的计算表明，在包括欧洲和北美西部在内的一些地区，这种转变可能已经发生，并可能在其他地方迫在眉睫：到2080年，全球61%以上的陆地表面(不包括南极洲)出现干旱/暴雨条件。相对于不断变化的基线，特大暴雨风险要么不会改变，要么略有降低。然而，极端干湿降水事件的频率和强度的增加可能会带来比目前所经历的任何挑战都更大的适应挑战。在许多地区，对未来危险的适应能力将需要适应不断变化的“正常”，其特点是前所未有的干旱化/湿化，不时出现更严重的极端情况。
Twenty-first century trends in hydroclimate are so large that future average conditions will, in most cases, fall into the range of what we would today consider extreme drought or pluvial states. Using large climate model ensembles, we remove the background trend and find that the risk of droughts and pluvials relative to that (changing) baseline is fairly similar to the 20th century risk. By continually adapting to long-term background changes, these risks could therefore perhaps be minimized. However, increases in the frequency of extremely wet and dry years are still present even after removing the trend, indicating that sustainably managing hydroclimate-driven risks in a warmer world will face increasingly difficult challenges. Variability in hydroclimate impacts natural and human systems worldwide. In particular, both decadal variability and extreme precipitation events have substantial effects and are anticipated to be strongly influenced by climate change. From a practical perspective, these impacts will be felt relative to the continuously evolving background climate. Removing the underlying forced trend is therefore necessary to assess the relative impacts, but to date, the small size of most climate model ensembles has made it difficult to do this. Here we use an archive of large ensembles run under a high-emissions scenario to determine how decadal “megadrought” and “megapluvial” events—and shorter-term precipitation extremes—will vary relative to that changing baseline. When the trend is retained, mean state changes dominate: In fact, soil moisture changes are so large in some regions that conditions that would be considered a megadrought or pluvial event today are projected to become average. Time-of-emergence calculations suggest that in some regions including Europe and western North America, this shift may have already taken place and could be imminent elsewhere: Emergence of drought/pluvial conditions occurs over 61% of the global land surface (excluding Antarctica) by 2080. Relative to the changing baseline, megadrought/megapluvial risk either will not change or is slightly reduced. However, the increased frequency and intensity of both extreme wet and dry precipitation events will likely present adaptation challenges beyond anything currently experienced. In many regions, resilience against future hazards will require adapting to an ever-changing “normal,” characterized by unprecedented aridification/wetting punctuated by more severe extremes.
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影响因子：
13.6
作者：
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