Statistical reconstruction of global vegetation for the last glacial maximum

We provide an estimate of global vegetation density for the Last Glacial Maximum (LGM) using a simple statistic model. For today's climate, vegetation is divided into 11 vegetation types plus bare soil, for each of which an empirical relationship between the probability of its occurrence and climate controls is derived. The relationships are then used to reconstruct the glacial vegetation patterns with and without considering CO2 modifications. For the LGM, the climate drivers are estimated from an ensemble-average of global paleo-climate simulations. The reconstruction suggests that vegetation types existing in today's cooler and drier regimes prevailed during the LGM and today's desert areas had more vegetation then. The vegetation patterns of the Amazon and Sahara are examined in detail. In the Amazon, tropical rainforest cover is reduced from 80% in today's climate to 40% in the LGM climate. The Sahara was partly covered by shrubs and grassland, with bare ground fraction reduced from 80% today to 30% in the LGM. The reconstructed vegetation patterns are compared with available biome data.