Multi vegetation model evaluation of the Green Sahara climate regime
Multi vegetation model evaluation of the Green Sahara climate regime
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DOI：
10.1002/2017gl073740
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发表时间：
2017-07-16
影响因子：
5.2
通讯作者：
Beerling, David J.
中科院分区：
文献类型：
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作者：
Hopcroft, Peter O.;Valdes, Paul J.;Beerling, David J.
在第四纪，撒哈拉沙漠定期被植被殖民，可能是因为轨道引起的降雨量增加。然而，气候模型模拟没有再现估计的水文变化，这削弱了对未来降雨预测的信心。我们使用三种不同的动态植被模型评估了过去的植被覆盖和气候的中全新世的定性信息之间的关系。与两个可用的植被重建相比，模型需要500- 800毫米的降雨量超过20度-25度N，这是显着大于推断花粉，但在很大程度上与最近的叶蜡生物标志物重建。响应的幅度也表明，所需的降雨制度的早至中全新世是远远不能正确地代表在大气环流模型。然而，与水分胁迫参数化、模拟现今植被的偏差以及古土壤分布的不确定性有关的模型间差异引入了不确定性，这些也与非洲湿润期的地球系统模型模拟有关。
During the Quaternary, the Sahara desert was periodically colonized by vegetation, likely because of orbitally induced rainfall increases. However, the estimated hydrological change is not reproduced in climate model simulations, undermining confidence in projections of future rainfall. We evaluated the relationship between the qualitative information on past vegetation coverage and climate for the mid-Holocene using three different dynamic vegetation models. Compared with two available vegetation reconstructions, the models require 500-800mmof rainfall over 20 degrees-25 degrees N, which is significantly larger than inferred from pollen but largely in agreement with more recent leaf wax biomarker reconstructions. The magnitude of the response also suggests that required rainfall regime of the early to middle Holocene is far from being correctly represented in general circulation models. However, intermodel differences related to moisture stress parameterizations, biases in simulated present-day vegetation, and uncertainties about paleosoil distributions introduce uncertainties, and these are also relevant to Earth system model simulations of African humid periods.