Resolving south Iran’s wet to dry Holocene transformation

Southern Iran today represents an arid region. However, studies of surface sediments and some archaeological data show that during certain periods of the Quaternary (i.e., the last 2.6 million years) much wetter conditions existed there and, for example, lakes existed where deserts are today. The most recent period of a "green" Iran appears to have occurred during the last summer solar radiation maximum in the first half of the Holocene (about 11,700 to 6000 years before present). The goal of this project is to establish high-resolution records of paleoclimate for this region based on precise age determinations. We will do this by examining dripstones from caves as "rain gauges" and climate archives to decipher climate and environmental history. These formations are one of the most important climate archives and require water (precipitation) for their growth. We will test the hypothesis that southern Iran was significantly wetter during the early Holocene than it is today, followed by a drying trend. Another objective is to determine the cause of this increased precipitation at that time. We will test the hypothesis that this additional precipitation came from summer rains of the Indian and/or African monsoons. Finally, we will investigate the question of whether the known climatic events of 8200 and 4200 years ago - periods of abrupt cooling in the Northern Hemisphere - coincided with dry periods in southern Iran. These investigations are of great importance in gaining a better understanding of the impact of climate change on the region.