Model uncertainties in climate change impacts on Sahel precipitation in ensembles of CMIP5 and CMIP6 simulations

Monerie, Paul‐Arthur; Wainwright, Caroline M.; Sidibé, Moussa; Akinsanola, A. A.

doi:10.1007/s00382-020-05332-0

Cited by 76 publications

(100 citation statements)

References 74 publications

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“…Over the western Sahel, monsoon precipitation tends to move southward. Although at a weaker intensity, similar changes have been obtained at a near-term time horizon (i.e., over the period 2010-2049) (Monerie et al, 2017) and with the RCP4.5 emission scenario (Monerie et al 2012;Akinsanola and Zhou 2018), and the CMIP6 Shared Socioeconomic Pathways (Almazroui et al 2020;Monerie et al 2020).…”

Section: Sahel Precipitation Forced Response To Global Warmingsupporting

confidence: 66%

“…Fontaine et al (2011b) have shown that a robust pattern emerges over the Sahel in response to global warming, with the majority of CMIP3 climate projections showing an increase in central Sahel precipitation and a decrease in western Sahel precipitation. This has also been shown within the CMIP5 ensemble (Monerie et al 2012(Monerie et al , 2013(Monerie et al , 2016Biasutti 2013;Roehrig et al 2013;James et al 2015;Diallo et al 2016;Gaetani et al 2017;Akinsanola and Zhou 2018;Dunning et al 2018) and the CMIP6 ensemble (Almazroui et al 2020;Monerie et al 2020). The multi-model ensemble also projects a modulation of the seasonal cycle of Sahel precipitation, with a decrease over the western Sahel occurring mainly during the early Sahel rainy season (i.e., May-June-July-August) and an increase over the central Sahel occurring mainly during the last months of the Sahel rainy season (i.e., August-September-October) (Biasutti 2013;Seth et al 2013;Monerie et al 2016;Dunning et al 2018).…”

Section: Introductionsupporting

confidence: 63%

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Future evolution of the Sahel precipitation zonal contrast in CESM1

et al. 2020

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The main focus of this study is the zonal contrast of the Sahel precipitation shown in the CMIP5 climate projections: precipitation decreases over the western Sahel (i.e., Senegal and western Mali) and increases over the central Sahel (i.e., eastern Mali, Burkina Faso and Niger). This zonal contrast in future precipitation change is a robust model response to climate change but suffers from a lack of an explanation. To this aim, we study the impact of current and future climate change on Sahel precipitation by using the Large Ensemble of the Community Earth System Model version 1 (CESM1). In CESM1, global warming leads to a strengthening of the zonal contrast, as shown by the difference between the 2060–2099 period (under a high emission scenario) and the 1960–1999 period (under the historical forcing). The zonal contrast is associated with dynamic shifts in the atmospheric circulation. We show that, in absence of a forced response, that is, when only accounting for internal climate variability, the zonal contrast is associated with the Pacific and the tropical Atlantic oceans variability. However, future patterns in sea surface temperature (SST) anomalies are not necessary to explaining the projected strengthening of the zonal contrast. The mechanisms underlying the simulated changes are elucidated by analysing a set of CMIP5 idealised simulations. We show the increase in precipitation over the central Sahel to be mostly associated with the surface warming over northern Africa, which favour the displacement of the monsoon cell northwards. Over the western Sahel, the decrease in Sahel precipitation is associated with a southward shift of the monsoon circulation, and is mostly due to the warming of the SST. These two mechanisms allow explaining the zonal contrast in precipitation change.

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Section: Sahel Precipitation Forced Response To Global Warmingsupporting

confidence: 66%

Section: Introductionsupporting

confidence: 63%

Future evolution of the Sahel precipitation zonal contrast in CESM1

et al. 2020

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“…The projected enhancement of the GM precipitation amount has been attributed to the combination of two opposing effects between the weakened monsoon circulation due to stabilization of the atmosphere and the increase of atmospheric moisture content due to atmospheric warming (Hsu et al, 2012; Lee & Wang, 2014). The changes in spatial pattern of monsoon precipitation has been attributed to the shifts of tropical circulation (Chadwick et al, 2013; Held & Soden, 2006; Monerie et al, 2020; Rowell & Chadwick, 2018). Wang et al (2020) pointed out that two greenhouse gas (GHG)‐induced thermodynamic effects, i.e., the increase of specific humidity and the increase of atmospheric stability due to top‐heavy heating, tend to offset each other; on the other hand, the GHG‐induced horizontally differential warming results in the robust “NH‐warmer‐than‐SH” and “land‐warmer‐than‐ocean” patterns, as well as an “El Niño–like warming” pattern, driving circulation change (the GHG‐induced dynamic effect) that plays a fundamental role in shaping the spatial patterns of the GM precipitation changes.…”

Section: Introductionmentioning

confidence: 99%

“…The increases in monsoon precipitation, however, have substantial intermodel spread (Hsu et al, 2013; Jayasankar et al, 2015; Kitoh et al, 2013; Monerie et al, 2016, 2020; Park et al, 2015; Rowell & Chadwick, 2018). It has been argued that the considerable uncertainty of GM precipitation may be influenced by different global warming rates among the CMIP5 models (Hsu et al, 2013; Oueslati et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…However, monsoon hydrological sensitivity, defined as precipitation change rate per kelvin of global warming, is also strongly model dependent (Hsu et al, 2013; Figure 1). The underlying mechanism for the intermodel spread in monsoon hydrological sensitivity remains elusive although studies have suggested the importance of the dynamic effect (Huang et al, 2013; Kent et al, 2015; Monerie et al, 2020; Rowell & Chadwick, 2018; Xie et al, 2015). Understanding what constrains the monsoon hydrological sensitivity is useful for increasing the confidence in projected precipitation change that guides water resource management.…”

Section: Introductionmentioning

confidence: 99%

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Sources of the Intermodel Spread in Projected Global Monsoon Hydrological Sensitivity

Cao

Wang

et al. 2020

Geophysical Research Letters

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The projected monsoon hydrological sensitivity, namely, the precipitation change rate per kelvin of global warming, shows substantial intermodel spread among 40 Coupled Model Intercomparison Project phase 5 models. The hydrological sensitivity of the Northern Hemisphere summer monsoon is negatively correlated with that of the Southern Hemisphere summer monsoon. The intermodel spread of the Northern Hemisphere summer monsoon hydrological sensitivity is mainly attributed to the projected interhemispheric temperature gradients and the associated low-level cross-equatorial flows. The intermodel spread of the Afro-Asia summer monsoon sensitivity is rooted in the projected continent-ocean thermal gradients, while the spread of the North American monsoon sensitivity is related to the projected sea surface temperature pattern in the tropical eastern Pacific and Atlantic. These findings suggest that further constraining monsoon hydrological sensitivity requires a better projection of the warming rate between the Northern and Southern Hemispheres and between the land and ocean, and the sea surface warming pattern in the tropical eastern Pacific and Atlantic. Plain Language Summary Global monsoon precipitation has far-reaching impacts on agriculture planning and social-economic sustainable development. Previous studies suggested that the increasing of global monsoon precipitation is sensitive to global warming rate, but the precipitation sensitivities, i.e., the precipitation change rate per kelvin of global warming, are also different among state-of-the-art coupled models. The causes of uncertainty in the monsoon precipitation sensitivity and the associated dominant physical mechanism remain elusive. Based on 40 state-of-the-art coupled climate models, we reveal that the greenhouse gas-induced interhemispheric temperature gradient causes the uncertainty of global monsoon precipitation sensitivity by changing the strengths of monsoon circulation and Hadley circulation and altering the Intertropical Convergence Zone position. Our results highlight the importance of a reliable projection of interhemispheric differential warming to the future change of global monsoon precipitation.

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Stratospheric Sulfate Aerosols impacts on West African monsoon precipitation using GeoMIP Models

Bonou¹,

Da‐Allada²,

Baloïtcha³

et al. 2021

Preprint

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Stratospheric Aerosol Geoengineering (SAG) is proposed to offset global warming; the use of this approach can impact the hydrological cycle. We use simulations from Coupled Model Intercomparison Project (CMIP5) and Geoengineering Model Intercomparison Project (G3 simulation) to analyze the impacts of SAG on precipitation (P) and to determine its responsible causes in West Africa and Sahel region. CMIP5 Historical data are firstly validated, the results obtained are consistent with those of observations data (CMAP and GPCP). Under the Representative Concentration Pathway (RCP) scenario RCP4.5, a slight increase is found in West Africa Region (WAR) relative to present-day climate. The dynamic processes especially the monsoon shifts are responsible for this change of precipitation. Under RCP4.5, during the monsoon period, reductions in P are 0.86%, 0.80% related to the present-day climate in the Northern Sahel (NSA), Southern Sahel (SSA) respectively while P is increased by 1.04% in WAR. Under SAG, 3.71% of P change (decrease) was associated with a -3.51 value of efficacy in the West African Region (AR). Under G3, a significant decrease of P is found in the West African region. This decrease in monsoon precipitation is mainly explained by changes in dynamics, which leads to weakened monsoon circulation and a shift in the distribution of monsoon precipitation. This result suggests that SAG deployment to balancing all warming can be harmful to rainfall in WAR if the amount of SO 2 to be injected in this tropical area is not taken into consideration.

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Model uncertainties in climate change impacts on Sahel precipitation in ensembles of CMIP5 and CMIP6 simulations

Cited by 76 publications

References 74 publications

Future evolution of the Sahel precipitation zonal contrast in CESM1

Future evolution of the Sahel precipitation zonal contrast in CESM1

Sources of the Intermodel Spread in Projected Global Monsoon Hydrological Sensitivity

Stratospheric Sulfate Aerosols impacts on West African monsoon precipitation using GeoMIP Models

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