TY - JOUR
T1 - Droughts, flooding events, and shifts in water sources and seasonality characterize last interglacial Levant climate
AU - Kiro, Yael
AU - Goldstein, Steven L.
AU - Kushnir, Yochanan
AU - Olson, Jennifer M.
AU - Bolge, Louise
AU - Lazar, Boaz
AU - Stein, Mordechai
N1 - We thank Bette Otto-Bliesner, John Kutzbach, and Efrat Morin for discussions. We thank Adi Torfstein for trace element data. This study was supported by the US NSF (Grant EAR- 1635391 to YK, SLG and YK), the US-Israel Binational Science Foundation (USIBSF, Grant # 2010375 to SLG and MS), the Dead Sea Drill Excellence Center of the Israel Science Foundation (grant # 1736/11 to BL), the Climate Center of Lamont-Doherty Earth Observatory, and the Storke Endowment of the Department of Earth and Environmental Sciences of Columbia University . Drilling for the Dead Sea Deep Drill Core was partly supported by NSF grant EAR 11–15312 . Jennifer Olson was a Research Experiences for Undergraduates student, supported by the LDEO NSF REU Grant OCE-1359194 . Y. Kushnir also acknowledges support from NSF award AGS-1734760. This is Dead Sea Excellence Center contribution #37 and LDEO contribution #8440. Author contributions - Yael Kiro: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Writing - original draft, Visualization, Supervision, Funding acquisition; Steven L. Goldstein: Conceptualization, Resources, Writing - original draft, Supervision, Funding acquisition; Yochanan Kushnir: Conceptualization, Methodology, Software, Resources, Writing - review & editing, Supervision; Jennifer M. Olson: Investigation; Louise Bolge: Methodology, Resources; Boaz Lazar: Funding acquisition; Mordechai Stein: Validation, Writing - review & editing, Funding acquisition.
PY - 2020/11/15
Y1 - 2020/11/15
N2 - Modern observations document increased drought frequency together with more intense precipitation and flooding in the world's semi-arid and arid regions as a consequence of the warming climate. Climate models predict that such conditions will intensify in the future, impacting millions of people. Paleoclimate studies can complement the short modern observational record and model projections by documenting climate changes in the past. Here we report major shifts in the geographic sources, intensity, and seasonality of Eastern Mediterranean precipitation during the unusually warm last interglacial period Marine Isotope Stage (MIS) 5e, reflecting global shifts in the rain and desert belts, based on 234U/238U-ratios in mineral precipitates in the Dead Sea, combined with evidence from climate model simulations. In the Dead Sea catchment 234U/238U ratios are indicators of water sources, where the Jordan River (flowing from the north) and the western catchments show high activity ratios between ∼1.5–1.7, and the eastern and southern catchments and flash floods (in the south-west, south and east) show lower ratios of 1.0–1.2. In Dead Sea water and precipitated minerals, 234U/238U is nearly always ∼1.45–1.55 during both glacials and interglacials. However, during the last interglacial MIS 5e insolation peak (∼127–122 ka) its value decreased to 1.2–1.3, and then to ∼1.0 towards its end (∼122–116 ka). During the insolation peak, the U-isotope data, combined with climate model runs forced with period orbital and greenhouse gas concentrations, indicate that rainfall associated with the African Summer Monsoon in the Dead Sea catchment accounted for ∼50% of the total annual rainfall, in stark contrast to present-day dry summers. The geochemical evidence indicates that following the insolation peak the region experienced an extremely dry period (although punctuated with wetter intervals), signifying expansion of the desert belt, similar to predicted effects of anthropogenic warming. This drying is partly supported by climate model runs forced with the appropriate changes in orbital parameters. The extreme drying during late MIS 5e between ∼122–116 ka reflected a major weakening of Mediterranean storm systems, resulting in a major decline of the Jordan River flow (indicated by the low 234U/238U ratios in the Dead Sea) and a relative increase in precipitation associated with the African Monsoon, shifting towards autumn. The Jordan River flow is estimated to be ∼10% of the present-day (pre-1964, prior to major diversion of the Jordan River and its sources for human use). Such changes, if they occur in the future, have serious implications for future water availability in the politically sensitive Middle East.
AB - Modern observations document increased drought frequency together with more intense precipitation and flooding in the world's semi-arid and arid regions as a consequence of the warming climate. Climate models predict that such conditions will intensify in the future, impacting millions of people. Paleoclimate studies can complement the short modern observational record and model projections by documenting climate changes in the past. Here we report major shifts in the geographic sources, intensity, and seasonality of Eastern Mediterranean precipitation during the unusually warm last interglacial period Marine Isotope Stage (MIS) 5e, reflecting global shifts in the rain and desert belts, based on 234U/238U-ratios in mineral precipitates in the Dead Sea, combined with evidence from climate model simulations. In the Dead Sea catchment 234U/238U ratios are indicators of water sources, where the Jordan River (flowing from the north) and the western catchments show high activity ratios between ∼1.5–1.7, and the eastern and southern catchments and flash floods (in the south-west, south and east) show lower ratios of 1.0–1.2. In Dead Sea water and precipitated minerals, 234U/238U is nearly always ∼1.45–1.55 during both glacials and interglacials. However, during the last interglacial MIS 5e insolation peak (∼127–122 ka) its value decreased to 1.2–1.3, and then to ∼1.0 towards its end (∼122–116 ka). During the insolation peak, the U-isotope data, combined with climate model runs forced with period orbital and greenhouse gas concentrations, indicate that rainfall associated with the African Summer Monsoon in the Dead Sea catchment accounted for ∼50% of the total annual rainfall, in stark contrast to present-day dry summers. The geochemical evidence indicates that following the insolation peak the region experienced an extremely dry period (although punctuated with wetter intervals), signifying expansion of the desert belt, similar to predicted effects of anthropogenic warming. This drying is partly supported by climate model runs forced with the appropriate changes in orbital parameters. The extreme drying during late MIS 5e between ∼122–116 ka reflected a major weakening of Mediterranean storm systems, resulting in a major decline of the Jordan River flow (indicated by the low 234U/238U ratios in the Dead Sea) and a relative increase in precipitation associated with the African Monsoon, shifting towards autumn. The Jordan River flow is estimated to be ∼10% of the present-day (pre-1964, prior to major diversion of the Jordan River and its sources for human use). Such changes, if they occur in the future, have serious implications for future water availability in the politically sensitive Middle East.
UR - http://www.scopus.com/inward/record.url?scp=85089268578&partnerID=8YFLogxK
U2 - https://doi.org/10.1016/j.quascirev.2020.106546
DO - https://doi.org/10.1016/j.quascirev.2020.106546
M3 - مقالة
SN - 0277-3791
VL - 248
JO - Quaternary Science Reviews
JF - Quaternary Science Reviews
M1 - 106546
ER -