Abstract. We present a transient simulation of global vegetation and climate patterns of the mid and late Holocene using the MPI-ESM (Max Planck Institute for Meteorology Earth System Model) at T63 resolution. The simulated vegetation trend is discussed in the context of the simulated Holocene climate change. Our model captures the main trends found in reconstructions. Most prominent are the southward retreat of the northern treeline that is combined with the strong decrease of forest in the high northern latitudes during the Holocene and the vast increase of the Saharan desert, embedded in a general decrease in precipitation and vegetation in the northern hemispheric monsoon margin regions. The southern hemisphere experiences weaker changes in total vegetation cover during the last 8000 years. However, the monsoon-related increase in precipitation and the insolation-induced cooling of the winter climate lead to shifts in the vegetation composition, mainly between the woody plant functional types (PFTs). The large-scale global patterns of vegetation almost linearly follow the subtle, approximately linear, orbital forcing. In some regions, however, non-linear, more rapid changes in vegetation are found in the simulation. The most striking region is the Sahel-Sahara domain with rapid vegetation transitions to a rather desertic state, despite a gradual insolation forcing. Rapid shifts in the simulated vegetation also occur in the high northern latitudes, in South Asia and in the monsoon margins of the southern hemisphere. These rapid changes are mainly triggered by changes in the winter temperatures, which go into, or move out of, the bioclimatic tolerance range of individual PFTs (Plant Functional Types). The dynamics of the transitions are determined by dynamics of the Net Primary Production (NPP) and the competition between PFTs. These changes mainly occur on timescales of centuries. More rapid changes in PFTs that occur within a few decades are mainly associated with the time scales of mortality and the bioclimatic thresholds implicit in the dynamic vegetation model, which have to be interpreted with caution. Most of the simulated Holocene vegetation changes outside the high northern latitudes are associated with modifications in the intensity of the global summer monsoon dynamics that also affect the circulation in the extra tropics via teleconnections. Based on our simulations, we thus identify the global monsoons as the key player in the Holocene climate and vegetation change.

中文翻译：

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MPI-ESM1.2中的全新世植被过渡及其气候驱动力

摘要。我们使用TPI分辨率的MPI-ESM（马克斯·普朗克气象地球系统模型）对全新世中期和晚期的全球植被和气候模式进行了瞬态模拟。在模拟全新世气候变化的背景下讨论了模拟植被趋势。我们的模型捕获了重建中发现的主要趋势。最突出的是北部林线的向南退缩，与全新世期间北部高纬度地区森林的大量减少以及撒哈拉沙漠的大量增加相结合，这是北半球季风中降水和植被普遍减少的原因边缘地区。在过去的8000年中，南半球的植被总变化较弱。然而，与季风有关的降水增加和日照诱发的冬季气候变冷导致植被组成发生变化，主要是在木本植物功能类型之间。大规模的全球植被格局几乎线性地遵循微妙的，近似线性的轨道强迫。然而，在某些地区，在模拟中发现了非线性的，植被变化更快的变化。最引人注目的地区是萨赫勒-撒哈拉沙漠地区，尽管有日晒强迫，但植被迅速过渡到相当荒凉的状态。模拟植被的快速变化也发生在北部高纬度地区，南亚和南半球的季风边缘。这些快速变化主要是由冬季温度的变化触发的，而冬季温度的变化会进入或移出 各个PFT（植物功能类型）的生物气候耐受范围。过渡的动态取决于净初级生产（NPP）的动态和PFT之间的竞争。这些变化主要发生在几个世纪的时间尺度上。在几十年内发生的PFT的更快变化主要与死亡的时间尺度和动态植被模型中隐含的生物气候阈值有关，必须谨慎解释。北部高纬度以外的大部分模拟的全新世植被变化与全球夏季风动力强度的变化有关，这些变化也通过遥距连接影响了热带地区的环流。根据我们的模拟，