Global vegetation response to astronomical forcing during nine interglacials in the past 800,000 years

Su, Qianqian [UCL] Yin, Qiuzhen [UCL] Wu, Zhipeng [UCL]

It is noted that certain recurring vegetation patterns appear to be a result of climate changes linked to specific astronomical parameters. Proxy reconstructions show that the response of vegetation to the astronomical forcing is complex and varies with regions. Our study aims at exploring the individual role of astronomical forcing on vegetation cover in several regions (Fig.1) from high latitudes to low latitudes under interglacial climate.For this purpose, we performed transient simulations for nine interglacials (MIS-19, MIS-17, MIS-15, MIS-13, MIS-11, MIS-9, MIS-7, MIS-5 and MIS-1) of the last 800ka with the model LOVECLIM where a dynamic vegetation model (VECODE) is included. Only the insolation forcings vary, GHGs and ice sheet being constant. We found that precipitation, GDD0 and vegetation respond strongly to the astronomical parameters in each interglacial and they are predominantly influenced by precession. In many regions, precipitation and GDD0 contribute oppositely to tree and grass growth. Tree fraction is mainly controlled by precipitation at mid and low latitudes, whereas the role of GDD0 increases towards high latitudes.Precession is more important for tree growth in low latitudes than high latitudes, whereas obliquity is more import in high latitudes. The response of grass fraction to astronomical parameters is more complex and varies in different latitude regions.