On the cause of abrupt vegetation collapse in North Africa during the Holocene: Climate variability vs. vegetation feedback

The abrupt desertification over the northern Africa in the mid-Holocene is studied in both a complex and a simple coupled climate-vegetation model. In contrast to the previous mechanism that relies on strong positive vegetation-climate feedback and the resulted multiple equilibria, we propose a new mechanism in which the abrupt desertification is caused by low frequency climate variability, rather than a positive vegetation-climate feedback. The implication of this new mechanism to modelling and observation is also discussed.