Holocene Palaeoclimate in the Saharo—Arabian Desert

Summary

Palaeoclimate data from the Saharo—Arabian region are reviewed to investigate their potential for deciphering shifts is nature and geographical extent of past precipitation regimes. Presently the northern sector of the Saharo—Arabian arid/semi-arid region receives much of its rainfall during the winter half of the year, in association with middle- to high-latitude westerly depressions. In contrast, the southern sector receives rain from the summer monsoons.

The early Holocene was marked by an increased northward extension of the monsoon regime in the whole region. The northern areas of Sahara and western Arabian Desert additionally show evidence of an increased southward penetration of winter rains. No comparable increase in early Holocene winter precipitation is observed in the eastern part of the Arabian Desert where only the summer monsoon dominates. An arid phase 8 ~ cal ka is observed in nearly all the sites studied. Following this, a renewed strengthening of winter rainfall in northern Sahara is observed. NW India too, in contrast to early Holocene, showed a clear trend of decreasing rainfall to the south, suggesting the possibility of higher winter rainfall. Subsequently, during mid- late Holocene a non-linear return towards present day aridity sets in, in the entire region. Although orbitally induced changes in insolation account for a large part of these shifts, the short term climatic fluctuations and the non-linear trend towards present day aridity would indicate complex interactions between atmosphere, ocean and land surface conditions.