Projected changes in the terrestrial and oceanic regulators of climate variability across sub-Saharan Africa

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Projected changes in the terrestrial and oceanic regulators of climate variability across sub‑Saharan Africa Michael Notaro1   · Fuyao Wang1 · Yan Yu2 · Jiafu Mao3 Received: 25 September 2019 / Accepted: 22 May 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract Future changes in the sign and intensity of ocean–land–atmosphere interactions have been insufficiently studied, despite implications for regional climate change projections, extreme event statistics, and seasonal climate predictability. In response to this deficiency, the present study focuses on projected responses to the enhanced greenhouse effect in: (1) the mean state of the atmosphere and land surface; (2) oceanic and terrestrial drivers of sub-Saharan climate variability; and (3) total seasonal climate predictability of sub-Saharan Africa, a region known for its pronounced land–atmosphere coupling. Analysis focuses on output from 23 Earth System Models in the Coupled Model Intercomparison Project Phase Five for the late twentieth and twenty-first centuries. It is projected that the greatest warming across sub-Saharan Africa will occur over the Sahel, the monsoon season will become more persistent into late summer and autumn, short rains in the Horn of Africa (HOA) will intensify, and leaf area index will increase across the HOA. Stepwise Generalized Equilibrium Feedback Assessment, i.e. a multivariate statistical approach, is applied to the model output over sub-Saharan Africa in order to explore the oceanic and terrestrial drivers of regional climate. The models indicate that the study region’s climate variability is dominated by oceanic drivers, with secondary contributions from soil moisture and very modest impacts from vegetation. Overall, the general model consensus of future projections indicates a concerning diminished seasonal predictability of sub-Saharan African regional climate based on key oceanic and terrestrial predictors and an elevated role of the land surface (associated with soil moisture anomalies) compared to oceanic drivers in regulating regional climate variability. Keywords  Earth system models · Land–atmosphere feedbacks · Feedbacks · Climate change · Africa Electronic supplementary material  The online version of this article (https​://doi.org/10.1007/s0038​2-020-05308​-0) contains supplementary material, which is available to authorized users. * Michael Notaro [email protected] Fuyao Wang [email protected] Yan Yu [email protected] Jiafu Mao [email protected] 1



Center for Climatic Research, Nelson Institute, University of Wisconsin-Madison, 1225 West Dayton Street, Madison, WI 53706, USA

2



Atmospheric and Oceanic Sciences Program, Princeton University, 300 Forrestal Road, Sayre Hall, Princeton, NJ 08540, USA

3

Climate Change Science Institute, Oak Ridge National Laboratory, MS 6301, PO Box 2008, Oak Ridge, TN 37831‑6201, USA



1 Introduction 1.1 African hydroclimate The current study focuses on sub-Saharan Africa, known for its distinct ecological and moisture gradients and heterogeneous landsc