On the cause of abrupt vegetation collapse in North Africa during the Holocene: Climate variability vs. vegetation feedback

Liu, Zhengyu; Wang, Yi; Gallimore, Robert G.; Notaro, Michael; Prentice, Iain Colin

doi:10.1029/2006gl028062

Cited by 106 publications

(107 citation statements)

References 17 publications

(30 reference statements)

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“…In addition, the simulations obtained with FOAM were consistent with the simulation results of other state-of-the-art climate models [40,41]. Furthermore, FOAM has been widely used in paleoclimate studies [42][43][44][45][46][47].…”

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confidence: 73%

Simulation of sea surface temperature changes in the Middle Pliocene warm period and comparison with reconstructions

et al. 2011

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The Middle Pliocene (ca 3.12-2.97 Ma) is a recent warm period in the Earth's history. In many respects, the warmth of the Middle Pliocene is similar to the probable warm situation of the late 21st century predicted by climate models. Understanding the Middle Pliocene climate is important in predicting the future climate with global warming. Here, we used the latest reconstructions for the Middle Pliocene-Pliocene Research Interpretation and Synoptic Mapping (PRISM) version 3-to simulate the Middle Pliocene climate with a fully coupled model Fast Ocean Atmosphere Model. From comparison of the results of simulations with reconstructions, we considered two important scientific topics of Middle Pliocene climate modeling: extreme warming in the subpolar North Atlantic and a permanent El Niño in the tropical Pacific. Our simulations illustrate that the global annual mean sea surface temperature (SST) in the Middle Pliocene was about 2.3°C higher than that in the pre-industrial era. The warming was stronger at mid-and high latitudes than at low latitudes. The simulated SST changes agree with SST reconstructions in PRISM3 data, especially for the North Atlantic, North Pacific and west coast of South America. However, there were still discrepancies between the simulation of the SST and reconstructions for the subpolar North Atlantic and tropical Pacific. In the case of the Atlantic, the weakened meridional overturning circulation in the simulation did not support the reconstruction of the extremely warm condition in the subpolar North Atlantic. In the case of the tropical Pacific, the whole ocean warmed, especially the eastern tropical Pacific, which did not support the permanent El Niño suggested by the reconstruction. From evaluation of the modeling and reconstruction, we suggest that the above discrepancies were due to uncertainties in reconstructions, difficulties in paleoclimate modeling and deficiencies of climate models. The discrepancies should be reduced through consideration of both the modeling and data.Middle Pliocene, sea surface temperature, permanent El Niño, numerical modeling, extreme warming Citation:Yan Q, Zhang Z S, Wang H J, et al. Simulation of sea surface temperature changes in the Middle Pliocene warm period and comparison with reconstructions. Chinese Sci Bull, 2011Bull, , 56: 890−899, doi: 10.1007 Paleoclimate modeling is employed to study paleoclimate evolution through numerical simulations using climate models. It is a tool for better understanding the mechanisms behind past time climate changes as well as a method of *Corresponding authors (email: yanqing@mail.iap.ac.cn; zhongshi.zhang@bjerknes.uib.no) evaluating the capability and effectiveness of climate models. A model that can reasonably simulate the past climate is thought to be more reliable in predicting the future climate. Over the past two decades, many geological studies have presented results on different time scales through reconstruction [1][2][3][4][5][6][7]. In terms of modeling, on the other hand,

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confidence: 73%

Simulation of sea surface temperature changes in the Middle Pliocene warm period and comparison with reconstructions

et al. 2011

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“…Several modeling studies suggest that positive feedbacks resulting from interactions between the landsurface and the atmosphere can amplify the climate response to forcings such as SSTs or solar variations (e.g., Doherty et al 2000). But the transient simulations of Liu et al (2006) suggest that strong low-frequency climate variability, rather than atmosphere/vegetation feedbacks, may be responsible for abrupt change in the region. Paeth and Thamm (2007) propose that until 2025, the impacts of land degradation and vegetation loss over tropical Africa may even be more important than global radiative heating for understanding climate change, and this is supported by Paeth et al (2009).…”

Section: Introductionmentioning

confidence: 99%

Northern African climate at the end of the twenty-first century: an integrated application of regional and global climate models

2009

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A method for simulating future climate on regional space scales is developed and applied to northern Africa. Simulation with a regional model allows for the horizontal resolution needed to resolve the region's strong meridional gradients and the optimization of parameterizations and land-surface model. The control simulation is constrained by reanalysis data, and realistically represents the present day climate. Atmosphere-ocean general circulation model (AOGCM) output provides SST and lateral boundary condition anomalies for 2081-2100 under a business-as-usual emissions scenario, and the atmospheric CO 2 concentration is increased to 757 ppmv. A ninemember ensemble of future climate projections is generated by using output from nine AOGCMs. The consistency of precipitation projections for the end of the twenty-first century is much greater for the regional model ensemble than among the AOGCMs. More than 77% of ensemble members produce the same sign rainfall anomaly over much of northern Africa. For West Africa, the regional model projects wetter conditions in spring, but a midsummer drought develops during June and July, and the heat stoke risk increases across the Sahel. Wetter conditions resume in late summer, and the likelihood of flooding increases. The regional model generally projects wetter conditions over eastern Central Africa in June and drying during August through September. Severe drought impacts parts of East Africa in late summer. Conditions become wetter in October, but the enhanced rainfall does not compensate for the summertime deficit. The risk of heat stroke increases over this region, although the threat is not projected to be as great as in the Sahel.

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“…Equilibrium simulations are often used to understand the mean climate state by giving a certain insolation or orbital parameters (longitude of perihelion, axial tilt and eccentricity) on a certain year or period (Kutzbach, 1981;Hewitt and Mitchell, 1998;Montoya et al, 2000;Liu et al, 2006). Such equilibrium simulations are unable to simulate the forcing effects of the varying astronomical parameters on the climate system.…”

Section: Model and Methodsmentioning

confidence: 99%

Modeling the climatic implications and indicative senses of the Guliya δ<sup>18</sup>O-temperature proxy record to the ocean–atmosphere system during the past 130 ka

et al. 2013

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Abstract. Using an intermediate-complexity UVic Earth System Climate Model (UVic Model), the geographical and seasonal implications and indicative senses of the Guliya temperature proxy found in the Guliya δ18O ice core record (hereinafter, the Guliya δ18O-temperature proxy record) are investigated under time-dependent orbital and CO2 forcings with an acceleration factor of 50 over the past 130 ka. The results reveal that the simulated August–September Guliya surface air temperature (SAT) reproduces the 21-ka precession and 43-ka obliquity cycles of the Guliya δ18O-temperature proxy record, showing an in-phase variation with the latter. Moreover, the Guliya δ18O-temperature proxy record may be also an indicator of the August–September Northern Hemispheric (NH) SAT. Corresponding to the difference between the extreme warm and cold phases of the precession cycle in the Guliya August–September SAT, there are two anomalous patterns in SAT and sea surface temperature (SST). The first anomalous pattern shows increases of SAT and SST toward the Arctic, which is possibly associated with an increase of the NH incoming solar radiation that is caused by the in-phase superposition between the precession and obliquity cycles. The second anomalous pattern shows increases of SAT and SST toward the equator, which is possibly due to a decrease of incoming solar radiation over the NH polar that results from the anti-phase counteraction between the precession and obliquity cycles. The summer (winter) Guliya and NH temperatures are higher (lower) in the warm phases of the August–September Guliya than in their cold phases. Moreover, in August–September, the Guliya SAT is closely related to the North Atlantic SST, in which the Guliya precipitation might act as a "bridge" linking the Guliya SAT and the North Atlantic SST.

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On the cause of abrupt vegetation collapse in North Africa during the Holocene: Climate variability vs. vegetation feedback

Cited by 106 publications

References 17 publications

Simulation of sea surface temperature changes in the Middle Pliocene warm period and comparison with reconstructions

Simulation of sea surface temperature changes in the Middle Pliocene warm period and comparison with reconstructions

Northern African climate at the end of the twenty-first century: an integrated application of regional and global climate models

Modeling the climatic implications and indicative senses of the Guliya δ<sup>18</sup>O-temperature proxy record to the ocean–atmosphere system during the past 130 ka

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On the cause of abrupt vegetation collapse in North Africa during the Holocene: Climate variability vs. vegetation feedback

Cited by 106 publications

References 17 publications

Simulation of sea surface temperature changes in the Middle Pliocene warm period and comparison with reconstructions

Simulation of sea surface temperature changes in the Middle Pliocene warm period and comparison with reconstructions

Northern African climate at the end of the twenty-first century: an integrated application of regional and global climate models

Modeling the climatic implications and indicative senses of the Guliya δ&lt;sup&gt;18&lt;/sup&gt;O-temperature proxy record to the ocean–atmosphere system during the past 130 ka

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Modeling the climatic implications and indicative senses of the Guliya δ<sup>18</sup>O-temperature proxy record to the ocean–atmosphere system during the past 130 ka