Respective impacts of Arctic sea ice decline and increasing greenhouse gases concentration on Sahel precipitation

Monerie, Paul‐Arthur; Oudar, Thomas; Sánchez-Gómez, Emilia

doi:10.1007/s00382-018-4488-5

Cited by 9 publications

(9 citation statements)

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“…Therefore, we assume that further work should be devoted to understanding better the establishment of the Northern Hemisphere temperature gradient, and its impact on Sahel precipitation variability. We speculate that uncertainties in simulating this large-scale gradients could arise from discrepancies between climate models to simulate atmospheric energy balance that has been linked to variations of the ITCZ (Schneider et al 2014a) and could be associated with errors in simulations of the cloud cover (Hwang and Frierson 2013) or could be associated with changes in Artic sea-ice (Deser et al 2014;Monerie et al 2018).…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2020

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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).

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Section: Discussionmentioning

confidence: 99%

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

et al. 2020

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“…The Arctic Ocean has lost about 3/4 of the sea-ice volume in the last four decades, which corresponds to an average reduction of SIE and SIT by half, at the end of the summer season [ 55 ]. The global warming effect shows a possible impact of Arctic sea-ice loss on tropical regions [ 56 ], which has some teleconnections and relationships with various global phenomena-Arctic Oscillation, Hadley circulation, North Atlantic Oscillation and Asian Summer Monsoon rainfall-and tropical climate processes [ 57 , 58 , 59 ]. The accelerated decline in sea-ice is associated with the weakening of the polar cell and an inconsistent increase in SLP over high latitude (60°N), along with the Urals–Siberia and Iceland low regions (Figures 6 and 7 ), whereas, it is also connected to the weakening of the three-cell circulations and a warmer SST in the midlatitude North Atlantic [ 60 ].…”

Section: Discussionmentioning

confidence: 99%

Global warming leading to alarming recession of the Arctic sea-ice cover: Insights from remote sensing observations and model reanalysis

Kumar

Yadav

Mohan

2020

Heliyon

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The present study quantifies the magnitude of Arctic sea-ice loss in the boreal summer (July–September), especially in September at different timescales (daily, monthly, annual and decadal). The investigation on the accelerated decline in the Arctic sea-ice was performed using different datasets of passive microwave satellite imagery and model reanalysis. Arctic sea-ice declined rapidly in the boreal summer (-10.2 ± 0.8 %decade −1 ) during 1979–2018, while, the highest decline in sea-ice extent (SIE) (i.e., 82,300 km 2 yr −1 /-12.8 ± 1.1 %decade −1 ) is reported in the month of September. Since late 1979, the SIE recorded the sixth-lowest decline during September 2018 (4.71 million km 2 ). Incidentally, the records of twelve lowest extents in the satellite era occurred in the last twelve years. The loss of SIE and sea-ice concentration (SIC) are attributed to the impacts of land-ocean warming and the northward heat advection into the Arctic Ocean. This has resulted in considerable thinning of sea-ice thickness (SIT) and reduction in the multiyear ice (MYI) for summer 2018. Global and Arctic land-ocean temperatures have increased by ~0.78 °C and ~3.1 °C, respectively, over the past 40 years (1979–2018) while substantial warming rates have been identified in the Arctic Ocean (~3.5 °C in the last 40-year) relative to the Arctic land (~2.8 °C in the last 40-year). The prevailing ocean-atmospheric warming in the Arctic, the SIE, SIC and SIT have reduced, resulting in the decline of the sea-ice volume (SIV) at the rate of -3.0 ± 0.2 (1000 km 3 decade −1 ). Further, it observed that the SIV in September 2018 was three times lower than September 1979. The present study demonstrates the linkages of sea-ice dynamics to ice drifting and accelerated melting due to persistent low pressure, high air-ocean temperatures, supplemented by the coupled ocean-atmospheric forcing.

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“…Africa is the world's second most populous continent and one of the most vulnerable continents with regard to climate change. The Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5) suggests that by the end of the twenty-first century, the mean annual surface temperature of Africa is likely to rise over 28C and precipitation patterns are likely to change too (IPCC 2013;Sylla et al 2016;Monerie et al 2017). These changes can have profound socioeconomic impacts, especially for the Sahara and Sahel.…”

Section: Introductionmentioning

confidence: 99%

“…In the late twentieth century a sustained Sahel drought severely affected ecosystem services, in the form of declines in forest area and food production (Epule et al 2014). In terms of future precipitation changes in the Sahara and Sahel, the magnitude and even the sign of these changes remain uncertain (Druyan 2011;Sylla et al 2016;Monerie et al 2017).…”

Section: Introductionmentioning

confidence: 99%

“…The climate research community has invested considerable efforts in the last two decades to understand the physical mechanisms that can affect climate variations in the Sahara and Sahel and the surrounding regions. Previous studies suggest that a number of factors can affect the weather and climate in the Sahara and Sahel, such as decadal to multidecadal variability of sea surface temperatures in different ocean basins (Giannini et al 2003;Mohino et al 2011;Fontaine et al 2011;Rodríguez-Fonseca et al 2015), aerosol and its indirect effects on clouds (Rotstayn and Lohmann 2002;Huang et al 2019), increases of greenhouse gases (Held et al 2005;Biasutti 2013, and references therein), Arctic sea ice variability (Smith et al 2017;Monerie et al 2019), and surface type changes (Charney et al 1977). The first and second West African Monsoon Modeling and Evaluation Project Experiment (WAMME I and WAMME II; Xue et al 2010;Xue et al 2016) used multimodel experiments to assess the contributions of different factors to the climatology of West African monsoon as well as the Sahel drought.…”

Section: Introductionmentioning

confidence: 99%

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The Effects of Surface Longwave Spectral Emissivity on Atmospheric Circulation and Convection over the Sahara and Sahel

et al. 2019

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This study quantifies the impact of the inclusion of realistic surface spectral emissivity in the Sahara and Sahel on the simulated local climate and beyond. The surface emissivity in these regions can be as low as 0.6–0.7 over the infrared window band while close to unity in other spectral bands, but such spectral dependence has been ignored in current climate models. Realistic surface spectral emissivities over the Sahara and Sahel are incorporated into the Community Earth System Model (CESM) version 1.1.1, while treatments of surface emissivity for the rest of the globe remain unchanged. Both the modified and standard CESM are then forced with prescribed climatological SSTs and fixed present-day forcings for 35-yr simulations. The outputs from the last 30 years are analyzed. Compared to the standard CESM, the modified CESM has warmer surface air temperature, as well as a warmer and wetter planetary boundary layer over the Sahara and Sahel. The modified CESM thus favors more convection in these regions and has more convective rainfall, especially in the Sahara. The moisture convergence induced by such inclusion of surface spectral emissivity also contributes to the differences in simulated precipitation in the Sahel and the region south to it. Compared to observations, inclusion of surface spectral emissivity reduces surface temperature biases in the Sahara and precipitation biases in the Gulf of Guinea but exacerbates the wet biases in the Sahara. Such realistic representation of surface spectral emissivity can help unmask other factors contributing to regional biases in the original CESM.

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Respective impacts of Arctic sea ice decline and increasing greenhouse gases concentration on Sahel precipitation

Cited by 9 publications

References 73 publications

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

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

Global warming leading to alarming recession of the Arctic sea-ice cover: Insights from remote sensing observations and model reanalysis

The Effects of Surface Longwave Spectral Emissivity on Atmospheric Circulation and Convection over the Sahara and Sahel

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