The impact of climate change on Sahel precipitation suffers from large uncertainties and is strongly model-dependent. In this study, we analyse sources of inter-model spread in Sahel precipitation change by decomposing precipitation into its dynamic and thermodynamic terms, using a large set of climate model simulations. Results highlight that model uncertainty is mostly related to the response of the atmospheric circulation to climate change (dynamic changes), while thermodynamic changes are less uncertain among climate models. Uncertainties arise mainly because the models simulate different shifts in atmospheric circulation over West Africa in a warmer climate. We linked the changes in atmospheric circulation to the changes in Sea Surface Temperature, emphasising that the Northern hemispheric temperature gradient is primary to explain uncertainties in Sahel precipitation change. Sources of Sahel precipitation uncertainties are shown to be the same in the new generation of climate models (CMIP6) as in the previous generation of models (CMIP5).

气候变化对萨赫勒地区降水的影响具有很大的不确定性，并且强烈依赖于模型。在这项研究中，我们使用大量的气候模型模拟，通过将降水分解为动力学和热力学项来分析萨赫勒地区降水变化的模式间传播源。结果表明，模型不确定性主要与大气环流对气候变化（动态变化）的响应有关，而热力学变化在气候模型之间的不确定性较小。不确定性的产生主要是因为这些模型模拟了在温暖气候下西非大气环流的不同变化。我们将大气环流的变化与海表温度的变化联系起来，强调北半球温度梯度是解释萨赫勒降水变化不确定性的主要因素。萨赫勒地区降水不确定性的来源在新一代气候模型（CMIP6）中与上一代模型（CMIP5）相同。