Validity of estimating flood and drought characteristics under equilibrium climates from transient simulations
Validity of estimating flood and drought characteristics under equilibrium climates from transient simulations
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DOI：
10.1088/1748-9326/ac27cc
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发表时间：
2021-10
影响因子：
6.7
通讯作者：
J. Boulange;N. Hanasaki;Y. Satoh;T. Yokohata;H. Shiogama;P. Burek;W. Thiery;D. Gerten;Hannes Müller Schmied;Y. Wada;S. Gosling;Y. Pokhrel;N. Wanders
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文献类型：
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作者：
J. Boulange;N. Hanasaki;Y. Satoh;T. Yokohata;H. Shiogama;P. Burek;W. Thiery;D. Gerten;Hannes Müller Schmied;Y. Wada;S. Gosling;Y. Pokhrel;N. Wanders
据预测，未来的洪水和干旱风险将在全球变暖分别比工业化前水平高出1.5 °C和2.0 °C时从中等水平过渡到高水平。然而，这些结果是通过使用稳定变暖的瞬态模拟来近似平衡气候而获得的。这种方法最近受到批评，由于全球陆地温度较暖，与平衡气候相比，瞬态气候的平均降水强度较高。因此，目前尚不清楚在瞬变气候下预测的洪水和干旱是否可以系统地替代在平衡气候下发生的洪水和干旱。在这里，通过采用一个大的合奏全球水文模型（HM）迫使全球气候模型，我们评估的有效性估计洪水和干旱特征下的平衡气候从瞬态模拟。洪水特性的差异下瞬态和平衡的气候可以在很大程度上归因于自然变率，表明洪水来自一个瞬态的气候合理地接近洪水预期在一个同样温暖，平衡的气候。相比之下，在全球陆地面积比自然变化所预期的更大的范围内，检测到短暂气候和平衡气候之间干旱强度的显著差异。尽管HMs在代表低径流制度方面存在很大差异，但我们发现，在短暂气候下发生的干旱强度可能无法有效地代表全球约6.7%的土地面积在同样温暖的平衡气候中的强度。
Future flood and drought risks have been predicted to transition from moderate to high levels at global warmings of 1.5 °C and 2.0 °C above pre-industrial levels, respectively. However, these results were obtained by approximating the equilibrium climate using transient simulations with steadily warming. This approach was recently criticised due to the warmer global land temperature and higher mean precipitation intensities of the transient climate in comparison with the equilibrium climate. Therefore, it is unclear whether floods and droughts projected under a transient climate can be systematically substituted for those occurring in an equilibrated climate. Here, by employing a large ensemble of global hydrological models (HMs) forced by global climate models, we assess the validity of estimating flood and drought characteristics under equilibrium climates from transient simulations. Differences in flood characteristics under transient and equilibrium climates could be largely ascribed to natural variability, indicating that the floods derived from a transient climate reasonably approximate the floods expected in an equally warm, equilibrated climate. By contrast, significant differences in drought intensity between transient and equilibrium climates were detected over a larger global land area than expected from natural variability. Despite the large differences among HMs in representing the low streamflow regime, we found that the drought intensities occurring under a transient climate may not validly represent the intensities in an equally warm equilibrated climate for approximately 6.7% of the global land area.