Hybrid insolation forcing of Pliocene monsoon dynamics in West Africa

Kuechler, Rony R.; Dupont, Lydie M; Schefuß, Enno

doi:10.5194/cp-14-73-2018

Cited by 27 publications

(57 citation statements)

References 65 publications

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“…are consistent with geological evidence which suggests a more humid climate during the mid-Pliocene (Kuechler et al, 2018;Salzmann et al, 2008). Some regional differences occur among the ensembles, mainly along the coast of Guinea where some models indicate drier conditions while other indicate a rainfall increase.…”

Section: Resultssupporting

confidence: 87%

“…Analysis of e.g. dust records of the coast of West Africa also indicates a strengthened West African Monsoon (WAM) during the mPWP as well as wetter conditions over West Africa and the Sahara region (Kuechler et al, 2018;Salzmann et al, 2008). 60…”

Section: Introduction 45mentioning

confidence: 99%

“…Palynological data records indicate a higher density of tree cover and an expansion of woodland and savanna in Northern Africa at the expense of deserts (Bonnefille, 2010;Salzmann et al, 2008) and multi-proxy studies analyzing e.g. plant-wax and dust records in marine sediment cores taken off-shore of West Africa indicate 250 wetter conditions during the mid-Pliocene (deMenocal, 2004;Feakins et al, 2005;Kuechler et al, 2018), which is qualitatively consistent with the results from the PlioMIP2 ensemble (Fig. 2).…”

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confidence: 99%

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Mid-Pliocene West African Monsoon Rainfall as simulated in the PlioMIP2 ensemble

Berntell¹,

Zhang²,

Li³

et al. 2021

Preprint

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Abstract. The mid-Pliocene Warm Period (mPWP; ~3.2 million years ago) is seen as the most recent time period characterized by a warm climate state, with similar modern geography and ~400 ppmv atmospheric CO2 concentration, and is therefore often considered an interesting analogue for near-future climate projections. Paleoenvironmental reconstructions indicate higher surface temperatures, decreasing tropical deserts, and a more humid climate in West Africa characterized by a strengthened West African Monsoon (WAM). Using model results from the second phase of the Pliocene Modelling Intercomparison Project (PlioMIP2) ensemble we analyze changes of the WAM rainfall during the mPWP, by comparing with the control simulations for the pre-industrial period. The ensemble shows a robust increase of the summer rainfall over West Africa and the Sahara region with an average increase of 2.7 mm/day, contrasted by a rainfall decrease over the equatorial Atlantic. An anomalous warming of the Sahara Desert and deepening of the Saharan Heat Low, seen in > 90 % of the models, leads to a strengthening of the WAM and an increased monsoonal flow into the continent. A similar warming of the Sahara Desert is seen in future projections using both phase 3 and 5 of the Coupled Model Intercomparison Project (CMIP3 and CMIP5), and though previous studies of future projections indicate a west/east drying/wetting contrast over Sahel, PlioMIP2 simulations indicate a uniform rainfall increase over Sahel in warm climates characterized by increasing greenhouse gas forcing.

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Section: Resultssupporting

confidence: 87%

Section: Introduction 45mentioning

confidence: 99%

mentioning

confidence: 99%

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Mid-Pliocene West African Monsoon Rainfall as simulated in the PlioMIP2 ensemble

Berntell¹,

Zhang²,

Li³

et al. 2021

Preprint

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“…In North Africa, hydrological conditions are controlled by the position of the tropical rainbelt over the African continent (Nicholson, ). The position of the tropical rainbelt is in turn influenced by precession‐forced variability in summer insolation (e.g., deMenocal et al, ; Kuechler et al, ; Kutzbach & Liu, ). However, in sub‐Saharan Northwest Africa, insolation is not of major influence on the position of the tropical rainbelt during the studied period (Castañeda et al, ).…”

Section: Discussionmentioning

confidence: 99%

Late Quaternary Biomass Burning in Northwest Africa and Interactions With Climate, Vegetation, and Humans

Schreuder

Hopmans

Castañeda

et al. 2019

Paleoceanog and Paleoclimatol

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Biomass burning on the African continent is widespread, and interactions with climate, vegetation dynamics, and biogeochemical cycling are complex. To obtain a better understanding of these complex relationships, African fire history has been widely studied, although mostly on relatively short timescales (i.e., years to kiloyears) and less commonly on long‐term scales. Here we present a 192‐kyr, continuous biomass‐burning record from sub‐Saharan Northwest Africa based on the fire biomarker levoglucosan in a marine sediment core offshore Guinea. Notable features of our record include an increase in levoglucosan accumulation at 80 ka and two peaks at 50–60 ka. The event at 80 ka is likely related to an overall increase in sedimentation rates rather than an increase in biomass burning in the Northwest African savanna region. Our record indicates that glacial/interglacial changes in regional climate and vegetation composition (C3 vs. C4 plants) were not a major influence on biomass burning over the last 192 kyr. However, we suggest that the burning events at 50–60 ka might be caused by increased occurrence of C3 vegetation and human settlement in this region. At this time, the savanna region became wetter and fuel loads likely increased. Therefore, the region was more hospitable for humans, who likely used fire for hunting activities. Collectively, we hypothesize that on longer (glacial/interglacial) timescales, biomass burning, regional climate, and African vegetation are not necessarily coupled, while around 50–60 ka, higher fuel loads and human fire use may have influenced fire occurrence in sub‐Saharan Northwest Africa.

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“…Some paleoclimate records associated with estimates of C 4 biomass, such as compound-specific isotope analyses of terrestrial leaf waxes in Pliocene marine sediments off of West Africa (Kuechler et al, 2018), are consistent with a relationship between aridity and C 4 biomass during a time with atmospheric pCO 2 ≥300 ppmV (i.e., above pre-industrial values; Foster et al, 2017). However, similar records from Pleistocene marine sediments off of North Africa (e.g., Kuechler et al, 2013) indicate an inverse relationship between regional aridity in northern Africa and C 4 abundance against a background of low, but fluctuating glacial-interglacial pCO 2 (see also Urban et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Climatic Controls on C4 Grassland Distributions During the Neogene: A Model-Data Comparison

et al. 2018

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Fox et al. Neogene C 4 Grasslands: Model-Data Comparison comparisons, suggesting that regional to local ecological interactions, continent-specific plant evolutionary histories, and/or regional to local climatic conditions not represented in global scale OAGCMs may have been equally strong or stronger in driving the evolution of C 4 grasslands as global changes in the Earth system such as decreases in atmospheric pCO 2 and late Cenozoic global cooling and/or aridification.

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Hybrid insolation forcing of Pliocene monsoon dynamics in West Africa

Cited by 27 publications

References 65 publications

Mid-Pliocene West African Monsoon Rainfall as simulated in the PlioMIP2 ensemble

Mid-Pliocene West African Monsoon Rainfall as simulated in the PlioMIP2 ensemble

Late Quaternary Biomass Burning in Northwest Africa and Interactions With Climate, Vegetation, and Humans

Climatic Controls on C4 Grassland Distributions During the Neogene: A Model-Data Comparison

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