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The Qarun Lake in the Faiyum Oasis (Egypt) provides a unique record of Holocene environmental and climate change in an arid area largely devoid of fossil proxy records. Multiple lithological, palaeontological and geochemical proxies and 32 radiocarbon dates from the 26-m-long core FA-1 provide a time series of the lake's transformation. Our results confirm that a permanent lake appeared in the Holocene at c. 10 cal. ka BP. The finely laminated lake sediments consist of diatomite, in which diatoms and ostracods together with lower concentrations of ions indicate a freshwater environment at the end of the early and middle Holocene. This freshwater supply was closely associated with regular inflows of the Nile water during flood seasons, when the Intertropical Convergence Zone ( ITCZ) migrated northwards in Africa, although it has probably never reached the Faiyum Oasis. Local rainfall, possibly connected with a northern atmospheric circulation, may have been important during winter. Several phases in the lake's evolution are recognized, represented by oscillations between deep open freshwater conditions during more humid climate and shallow fresh to brackish water during drier episodes. After a long freshwater phase, the lake setting has become more brackish since c. 6.2 cal. ka BP as indicated by diatoms and increasing contents of evaporite ions in the sediment. This clearly shows that since that time the lake has occasionally become partly desiccated. This is a result of reduced discharge of the Nile. In the late Holocene the lake was mostly brackish and then gradually turned into a saline lake. This natural process was interrupted about 2.3 cal. ka BP when a man-made canal facilitated water inflow from the Nile. The examined FA-1 core can be used as a reference age model of climate change in the Holocene and its impact on the development and decline of ancient civilizations in northeastern Africa. [ABSTRACT FROM AUTHOR]

This study reports the high-resolution (50–100 yr) temporal variations of quartz roundness used as a climate proxy in the sediment core FA-1 recovered in the Faiyum Basin of the lower Nile. A higher proportion of transparent angular quartz can be found in sediment transported from the upper to the lower Nile via runoff when the Intertropical Convergence Zone (ITCZ) migrated northwards during the Holocene. The stained rounded quartz in the core sediment can be linked to windblown input into the Faiyum Basin from the Sahara Desert when the ITCZ shifted southwards. Using this theory, we reconstructed the series of Holocene climate changes in relation to the ITCZ migration. Our quartz evidence revealed: 1) the African Humid Period (AHP) occurring in the basin at 9200–4200 cal. yrs BP; 2) a short-term (5800–5400 cal. yrs BP) aridification occurred during the AHP; and 3) the rapid onset of hyper-aridification at ca. 4200–4000 years ago, which then persisted. These ITCZ related climate pulses, have basin-wide implications supporting relevant paleoclimate studies in North Africa. In addition, our results suggested at least 3 times when hydro-geoengineering works were implemented to source water from the Nile for local farming during the hyper-aridification period. [ABSTRACT FROM AUTHOR]

To investigate how Holocene climate patterns influenced the development of early Egyptian agriculture at the archaeological site of Sais on the Nile Delta, we conducted a palynological study. Seven palynological zones were defined to reveal Holocene climate fluctuations. Zone I (ca. 9000–7000 cal yr BP) was a period of warming climate, succeeded by a progressive drying climate phase in Zones II–VII (ca. 7000–2000 cal yr BP). Pollen records indicate Nile flooding prevailed before 7000 years ago, making the study area uninhabitable, before it later developed into a wetland setting. The earliest farming started at ca. 6700 cal yr BP, as indicated by the abrupt appearance of cereal (Poaceae > 35 μm), during a time of climate warming (Zone III), This material can be differentiated from wild Poaceae (<35 μm), which occurs throughout the profile, indicating the cereal was introduced to this area for agriculture. Results further reveal the transformation of human activities, from passive adaptation to climate, to actively remolding the environment against the background of long-term drying. During the early farming stage (ca. 6700–5500 cal yr BP), climate-human indicators were synchronous in distribution, suggesting lower pressure from climate change on population growth; however, this reversed from ca. 5500 cal yr BP, as intensive agriculture was required to meet shortages of natural resources during climate drying. Perhaps, the best evidence for adaptation is the increased abundance of Azolla from ca. 4000 years ago, a fern that favours growing in still-water bodies, hinting that much more irrigation was required at the time to sustain societal development. • A palynological profile is described at the Sais archaeological site, Nile Delta. • High-resolution studies reveal centennial fluctuations in pollen-climate through Holocene times. • The earliest farming and adaptation to climate change commenced 6700 cal yrs. BP. • Two mechanisms of climate-societal development are proposed. [ABSTRACT FROM AUTHOR]

Human perturbation and its impact on vegetation and plant diversity during the Holocene have caused serious concerns for the biogeological and geoarchaeological communities. As a centre of origin of rice agriculture, the lower Yangtze region (LYR) has a long history of human occupation over most of the Holocene. However, early anthropogenic impacts on the ecosystem of the region remain elusive. Here we present a multidisciplinary study including pollen and charcoal analysis on three different sediment cores (TJA, YJ1503 and PW) along a gradient of human interference to disentangle human and climatic influences on vegetation in the coastal area of the LYR. The results show that rice farming which developed after an environmental transition from salt marsh to freshwater wetland was mainly assisted by fire, particularly slash-and-burn practices by the Neolithic people between 7 and 4 kyr BP. Both the vegetation composition and plant diversity of the mixed forests of the LYR responded to these early human perturbations with a threshold effect. However, whereas plant diversity rapidly recovered when human activity ceased/weakened, the vegetation composition showed differences from the pre-fire condition, indicating a lasting effect. We propose that the varied post-fire recovery strategies of different species, e.g. Quercus evergreen comp. versus Pinus massonania , would account for this discrepancy. • Pollen and charcoal were analyzed for three sediment cores along a gradient of human interference. • Human impact on vegetational change occurred since 6.6 kyr BP with a lasting effect. • Fire interference reduced plant diversity with a threshold effect. [ABSTRACT FROM AUTHOR]