Wetlands of North Africa During the Mid‐Holocene Were at Least Five Times the Area Today

Chen, Weizhe; Ciais, Philippe; Qiu, Chunjing; Ducharne, Agnès; Zhu, Dan; Peng, Shushi; Braconnot, Pascale; Huang, Chunju

doi:10.1029/2021gl094194

Cited by 8 publications

(8 citation statements)

References 54 publications

(136 reference statements)

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“…North Africa is one key region for considering abrupt climate change (Petit-Maire and Guo 1996, 1999, de Menocal et al 2000. During periodic 'African Humid Periods' (AHPs) much of today's Sahara desert was transformed by wetter conditions to a region of shrub and savannah vegetation (Hoelzmann et al 1998, Hély et al 2014, wetlands (Brostrom et al 1998, Krinner et al 2012, Chen et al 2021 and human settlements (Kuper andKropelin 2006, Manning andTimpson 2014). The strong environmental response in North Africa is due to the profound influence of the seasonality of insolation on the tropical hydrological cycle which is controlled by long-term variations in Earth's orbit around the Sun (e.g.…”

Section: Introductionmentioning

confidence: 99%

Green Sahara tipping points in transient climate model simulations of the Holocene

Hopcroft

Valdes

2022

Environ. Res. Lett.

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The ‘Greening’ and subsequent desertification of the Sahara during the early to mid-Holocene is a dramatic example of natural climate change. We analyse a suite of simulations with a newly palaeo-conditioned configuration of the HadCM3 coupled model that is able to capture an abrupt desertification of North Africa during this time. We find that this model crosses a threshold of moisture availability for vegetation at around 6000 years before present. The resultant rapid reduction in vegetation cover acts to reduce precipitation through moisture recycling and surface albedo feedbacks. Precursor drying events which are not directly forced also indicate that the model is close to a critical moisture level. Similar precursor-like events appear in a Holocene record from the East of the continent, hinting that the natural system may resemble some of the properties of this model simulation. The overall response is not fundamentally altered by the inclusion of solar irradiance variations or volcanic eruptions. The simulated timing of the abrupt transition is mostly controlled by orbital forcing and local positive feedbacks, but it is also modulated to some extent by the state of the atmosphere and ocean. Comparisons with proxy records across North Africa show good agreement with the model simulations, although the simulations remain overly dry in the East. Overall, a threshold response may present a useful model of the real transition, but more high-resolution palaeoclimate records would help to discriminate among the predictions of climate models.

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Section: Introductionmentioning

confidence: 99%

Green Sahara tipping points in transient climate model simulations of the Holocene

Hopcroft

Valdes

2022

Environ. Res. Lett.

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“…First, the potential wetland extent would become drainage if the warming-induced increasing evapotranspiration is not matched by an equivalent increase in precipitation . The current potential wetland extent simulation is based on CTI, ,,, which combines the past 50 years’ average precipitation and evaporation in China but overlooks the influence of future climate change. Using the projected precipitation and evapotranspiration is more reasonable, but the predicted evapotranspiration from wetlands could not be accurately predicted by the current ESMs .…”

Section: Discussionmentioning

confidence: 99%

Methane Emissions from Wetlands in China and Their Climate Feedbacks in the 21st Century

Canadell

Yang

et al. 2022

Environ. Sci. Technol.

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Wetlands are large sinks of carbon dioxide (CO 2 ) and sources of methane (CH 4 ). Both fluxes can be altered by wetland management (e.g., restoration), leading to changes in the climate system. Here, we use multiple models to assess CH 4 emissions and CO 2 sequestration from the wetlands in China and the impacts on climate under three climate scenarios and four wetland management scenarios with various levels of wetland restoration in the 21st century. We find that wetland restoration leads to increased CH 4 emissions with a national total of 0.32−11.31 Tg yr −1 . These emissions induce an additional radiative forcing of 0.0005−0.0075 W m −2 yr −1 and global annual mean air temperature rise of 0.0003− 0.0053 °C yr −1 , across all future climate and management scenarios. However, wetland restoration also resulted in net CO 2 sequestration, leading to a combined net greenhouse gas sink in all climate management scenarios, except in the highest restoration level combined with the hottest climate scenario. The highest climate cooling was achieved under medium restoration, with the climate scenario consistent with the Paris agreement target of below 2 °C, with a cumulative global warming potential of −3.2 Pg CO 2 -eq (2020− 2100). Wetland restoration in the Qinghai−Tibet Plateau offers the greatest cooling effect.

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“…The availability of such data paved the way for a large number of research questions among many disciplines, i.e. ecology (Miller et al 2021b, VanBuren and Jarzyna 2022), paleoecology (Leonardi et al 2018, 2022, Somveille et al 2020, Chen et al 2021, Schap et al 2021, Thorup et al 2021, Medina‐Castañeda et al 2022, Reade et al 2022), conservation (Beyer and Manica 2021), population genetics (Maisano Delser et al 2021, Miller et al 2021a, Warmuth et al 2021), archaeology (Betti et al 2020, Racimo et al 2020, Beyer et al 2021, Krzyzanska et al 2021, Bradshaw et al 2022, Cerasoni et al 2022, Park and Marwick 2022, Timbrell et al 2022), macroevolution of different taxa, including the genus Homo (Saupe et al 2014, Will et al 2021, Fordham et al 2022, Timmermann et al 2022, Troyer et al 2022), anthropology (Leonardi et al 2017, Padilla‐Iglesias et al 2022) and linguistics (Beyer et al 2019).…”

Section: Introductionmentioning

confidence: 99%

pastclim 1.2: an R package to easily access and use paleoclimatic reconstructions

et al. 2023

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The recent development of continuous paleoclimatic reconstructions covering hundreds of thousands of years paved the way for a large number of studies from disciplines ranging from paleoecology to archaeology, conservation to population genetics, macroevolution to anthropology and human evolution to linguistics. Unfortunately, (paleo)climatic data can be challenging to extract and analyze for scholars unfamiliar with such specific file formats.Here we present pastclim, an R package facilitating the access and use of paleoclimatic reconstructions. It currently includes two of such datasets, covering respectively the last 120 000 and 800 000 years, and a vignette provides instructions on how to include additional datasets.The package contains a set of functions to quickly and easily recover the climate for time periods of interest either for the whole world or specific areas, extract data from locations scattered in space and/or time, retrieve time series from individual sites, and manage the ice or land coverage, offering a handy platform to include the climate of the past into existing or new analyses and pipelines.

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Wetlands of North Africa During the Mid‐Holocene Were at Least Five Times the Area Today

Cited by 8 publications

References 54 publications

Green Sahara tipping points in transient climate model simulations of the Holocene

Green Sahara tipping points in transient climate model simulations of the Holocene

Methane Emissions from Wetlands in China and Their Climate Feedbacks in the 21st Century

pastclim 1.2: an R package to easily access and use paleoclimatic reconstructions

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