Abstract Anthropogenic climate change, particularly through increased greenhouse gas (GHG) emissions, is projected to impact 21st century precipitation distribution, altering fluvial processes such as riverine water discharge and sediment dynamics, worldwide. Changes in fluvial water and sediment discharges can have profound impacts on the functioning and connectivity of earth's natural systems. In this paper, we study the natural sensitivity of water discharge and suspended sediment fluxes in large global river systems to predicted climate change in the 21st century. A global-scale hydro-geomorphic model (WBMsed) was forced with precipitation and temperature projections generated by five General Circulation Models (GCMs), each driven by four Representative Concentration Pathways (RCPs). Anthropogenic drivers were excluded from the simulations in order to isolate the signal of 21st century climate change. The results, based on an ensemble of model outputs, revealed that global river discharge and sediment dynamics are highly sensitive to anthropogenic climate change in the 21st century. Increasing global warming will lead to more extreme changes and greater rates of changes (increasing or decreasing) in both variables. Despite substantial regional heterogeneity, a global net increase is projected for both natural river discharge and sediment flux toward the end of the 21st century under all climate change scenarios. These increases are larger with increasing levels of atmospheric warming. At the end of this century, projected climate changes under RCP 2.6, 4.5, 6.0 and 8.5 scenarios, will lead to 2%, 6%, 7.5% and 11% increases respectively in mean global river discharge relative to the 1950–2005 period, while mean global suspended sediment flux will show 11%, 15%, 14% and 16.4% increases under pristine conditions. In addition to magnitudes, inter-annual variability also increases with increasing warming. Changes in sediment flux closely follow the patterns predicted for discharge, and are mostly driven by climate warming-induced spatial and temporal variation in precipitation. However, the relationship between precipitation, discharge and sediment flux was found to be non-linear both in space and time, demonstrating the utility of explicit modeling of both hydrology and geomorphology.

中文翻译：

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21 世纪全球河流水排放和悬浮泥沙动力学的气候诱导趋势

摘要 人为气候变化，特别是通过增加温室气体 (GHG) 排放，预计将影响 21 世纪的降水分布，改变世界范围内的河流过程，如河流排水和沉积物动力学。河流水和沉积物排放的变化会对地球自然系统的功能和连通性产生深远的影响。在本文中，我们研究了全球大型河流系统中排水量和悬浮泥沙通量的自然敏感性，以预测 21 世纪的气候变化。全球尺度水文地貌模型 (WBMsed) 由五个一般环流模型 (GCM) 生成的降水和温度预测强制执行，每个模型由四个代表性浓度路径 (RCP) 驱动。人为驱动因素被排除在模拟之外，以隔离 21 世纪气候变化的信号。基于模型输出集合的结果表明，全球河流流量和沉积物动态对 21 世纪的人为气候变化高度敏感。全球变暖加剧将导致两个变量发生更极端的变化和更大的变化率（增加或减少）。尽管存在很大的区域异质性，但在所有气候变化情景下，预计到 21 世纪末，自然河流流量和沉积物通量的全球净增加。随着大气变暖水平的增加，这些增加幅度更大。到本世纪末，RCP 2.6、4.5、6.0和8.5情景下预计的气候变化将导致2%、6%、7。与 1950-2005 年相比，全球河流平均流量分别增加了 5% 和 11%，而在原始条件下，全球平均悬浮泥沙通量将增加 11%、15%、14% 和 16.4%。除了震级之外，年际变化也随着变暖的增加而增加。沉积物通量的变化与预测的排放模式密切相关，主要是由气候变暖引起的降水时空变化驱动的。然而，发现降水、流量和沉积物通量之间的关系在空间和时间上都是非线性的，这证明了水文和地貌显式建模的实用性。在原始条件下增加 4%。除了震级之外，年际变化也随着变暖的增加而增加。沉积物通量的变化与预测的排放模式密切相关，主要是由气候变暖引起的降水时空变化驱动的。然而，发现降水、流量和沉积物通量之间的关系在空间和时间上都是非线性的，这证明了水文和地貌显式建模的实用性。在原始条件下增加 4%。除了震级之外，年际变化也随着变暖的增加而增加。沉积物通量的变化与预测的排放模式密切相关，主要是由气候变暖引起的降水时空变化驱动的。然而，发现降水、流量和沉积物通量之间的关系在空间和时间上都是非线性的，这证明了水文和地貌显式建模的实用性。