National Centre for Groundwater Research and Training, College of Science and Engineering, Flinders University, Adelaide, SA 5001, Australia
Abstract. This study identifies which factor, increased atmospheric CO2 concentration or local moisture deficit, dominates the temporal occurrence of hot extremes at the global scale. The wavelet decomposed GRACE Terrestrial Water Storage (TWS) is for the first time applied in examining the relationship between soil moisture (θ) and number of hot days in the hottest month (NHD). It reveals stronger θ–NHD relationships over larger areas than other commonly used soil moisture proxies (i.e., standardized precipitation index (SPI) and model derived product). During the study period 1985–2015, hot extreme occurrence with a dominant influence from increased atmospheric CO2 concentration is mainly observed in South America, Africa and Asia, while soil moisture deficit dominates the occurrence of hot extremes in larger areas, including parts of North America, West Europe, Australia, Southeast Asia and South Africa. Global action in reducing emissions will support combating hot extremes. In addition, important attention should be directed to address, e.g. by adaptive land management, the increasing moisture deficit in some regions.
How to cite. Chen, A., Guan, H., and Batelaan, O.: Relative importance of increased atmospheric CO2 concentration and local moisture deficit to hot extremes, Hydrol. Earth Syst. Sci. Discuss. [preprint], https://doi.org/10.5194/hess-2020-400, 2020.
Received: 03 Aug 2020 – Discussion started: 27 Aug 2020
It is well-known that global measures for reducing emissions are essential in combating hot extremes. This study indicates that local moisture deficit dominates hot extreme occurrence in regions with a total area twice as large as dominated by increased atmospheric CO2 concentration during 1985–2015. It suggests that to mitigate hot extremes, important attention should also be directed to address the increasing moisture deficit in some regions.
It is well-known that global measures for reducing emissions are essential in combating hot...