Vegetation, Ice and Deserts of the Paleo-Earth
Post date: Jul 26, 2011 9:43:36 PM
In our previous post we discussed the distribution of landmasses of the Paleo-Earth. Here we used the Visible Paleo-Earth (VPE) datasets to estimate the global surface coverage of vegetation, ice, and deserts in the last 750 million years, during the Phanerozoic (Figure 1). The vegetation regions were defined as any region with over 25% vegetation cover. Ice covered areas include permanent and mountain ice with over 75% ice cover. Deserts are those regions without ice and with less than 25% vegetation cover. We also included as vegetation cover the potential presence of simple photosynthetic eukaryote biota before the appearance of plants 450 Ma (Strother et al., 2011).
According to this preliminary analysis, Earth landmasses today are covered by about 68% vegetation, 11% ice, and 21% desert (Table 1). However, during the Devonian and Cretaceous vegetation cover reached 95%; Earth was a truly "forest planet." Last global glaciation (Snowball Earth) occurred before the Phanerozoic 650 Ma with over 60% ice cover. Later, and smaller, ice caps included the Ordovician, the Carboniferous-Permian, and today. Interestingly, Earth's today is in a period with the lowest global vegetation cover since the appearance of land plants 450 Ma.
Figure 1. Percent of surface coverage of vegetation, ice, and deserts in the last 750 million years. Dotted line correspond to today values (data shown in Table 1).
Table 1. Percent of surface coverage of vegetation, ice, and deserts in the last 750 million years.