page_title: Historic desertification
section_title: Research
hierarchical_section_title: Historic desertification / Research
caption_attribution_description: Ruins in Beit Ras, Capolitas.
context_page_description: Historic desertification is the study of the desert-forming process from a historic perspective. It was presumed in the past that the main causes of desertification lay in overuse of the land resulting in impoverishment of the soil, reduced vegetation cover, increased risk of drought and the resulting wind erosion. However recent projects to regreen deserts have not met with the success envisaged, and cast doubts on this theory. Research suggests that it is extreme events rather than drought caused by low annual precipitation, that do the most damage. Heavy downpours resulting in flash floods wash away sediment and there seems to have been an increased number of extreme events in the Levant at the end of the Byzantine period. The decline of settlements in the desert belt at this time may have been caused by these extreme events rather than a reduction in annual precipitation.
context_section_description: A number of running research projects in Jordan found that the erosion of the main agricultural soil, the Terra Rossa, took place at the end of the last Ice Age and during the Younger Dryas. It seems therefore that erosion of the today intensively used soils was limited during historical periods, and not connected with desertification. 
  The discussion about the impact of climate change on desertification focuses on drought. While some authors argue that periods of decline in the Levant were synchronous with reduced rainfall, others point to the non-linear development of settlement. However, a focus on annual precipitation allows only for limited conclusions about the productivity of agriculture. In this context, soils and colluvia point to an increased frequency of extreme rainfall events in the Levant at the end of the Byzantine period. As far as such events could be observed today, their associated damage was always enormous and could have had much more serious consequences than drought. The decline of settlement in the desert belt at the end of antiquity could be connected with an increase of extreme events.
caption: Sediments covering the theatre of Beit Ras (Capitolias)
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