Global River Discharge and Floods in the Warmer Climate of the Last Interglacial

Paolo Scussolini,Christian Stepanek,Pascale Braconnot,Pepijn Bakker,Chuncheng Guo,Philip J Ward,Dirk Eilander,Edwin H Sutanudjaja,Jeroen C J H Aerts,Ted I E Veldkamp,Qiong Zhang,Hiroaki Ikeuchi,Jannis M Hoch,Sanne Muis,Maria‐Vittoria Guarino,Dai Yamazaki,Bette L Otto‐Bliesner

doi:10.1029/2020gl089375

Abstract

AbstractWe investigate hydrology during a past climate slightly warmer than the present: the last interglacial (LIG). With daily output of preindustrial and LIG simulations from eight new climate models we force hydrological model PCR‐GLOBWB and in turn hydrodynamic model CaMa‐Flood. Compared to preindustrial, annual mean LIG runoff, discharge, and 100‐yr flood volume are considerably larger in the Northern Hemisphere, by 14%, 25%, and 82%, respectively. Anomalies are negative in the Southern Hemisphere. In some boreal regions, LIG runoff and discharge are lower despite higher precipitation, due to the higher temperatures and evaporation. LIG discharge is much higher for the Niger, Congo, Nile, Ganges, Irrawaddy, and Pearl and lower for the Mississippi, Saint Lawrence, Amazon, Paraná, Orange, Zambesi, Danube, and Ob. Discharge is seasonally postponed in tropical rivers affected by monsoon changes. Results agree with published proxies on the sign of discharge anomaly in 15 of 23 sites where comparison is possible.

Highlights

IntroductionThe need is pressing to anticipate the response of the hydrological cycle to increasing global temperatures
With ongoing climate change, the need is pressing to anticipate the response of the hydrological cycle to increasing global temperatures
We investigate hydrology during a past climate slightly warmer than the present: the last interglacial (LIG)

Summary

Introduction

The need is pressing to anticipate the response of the hydrological cycle to increasing global temperatures. The LIG has been abundantly studied in terms of temperature, using climate models (e.g., Lunt, Abe‐Ouchi, et al, 2013; Otto‐Bliesner et al, 2013, 2020) and with proxies covering some Northern Hemisphere continents and many ocean subbasins (Capron et al, 2017; Hoffman et al, 2017; Turney et al, 2020), and recently in terms of precipitation (Nikolova et al, 2013; Pedersen et al, 2017). Exceptions are the modeling of Holocene discharge for a set of large river basins (Aerts et al, 2006; Ward et al, 2007)

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Conclusion