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Baxter AJ, Verschuren D, Peterse F, Miralles DG, Martin-Jones CM, Maitituerdi A, Van der Meeren T, Van Daele M, Lane CS, Haug GH, Olago DO, Sinninghe Damsté JS. Reversed Holocene temperature-moisture relationship in the Horn of Africa. Nature 2023; 620:336-343. [PMID: 37558848 PMCID: PMC10412447 DOI: 10.1038/s41586-023-06272-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 05/25/2023] [Indexed: 08/11/2023]
Abstract
Anthropogenic climate change is predicted to severely impact the global hydrological cycle1, particularly in tropical regions where agriculture-based economies depend on monsoon rainfall2. In the Horn of Africa, more frequent drought conditions in recent decades3,4 contrast with climate models projecting precipitation to increase with rising temperature5. Here we use organic geochemical climate-proxy data from the sediment record of Lake Chala (Kenya and Tanzania) to probe the stability of the link between hydroclimate and temperature over approximately the past 75,000 years, hence encompassing a sufficiently wide range of temperatures to test the 'dry gets drier, wet gets wetter' paradigm6 of anthropogenic climate change in the time domain. We show that the positive relationship between effective moisture and temperature in easternmost Africa during the cooler last glacial period shifted to negative around the onset of the Holocene 11,700 years ago, when the atmospheric carbon dioxide concentration exceeded 250 parts per million and mean annual temperature approached modern-day values. Thus, at that time, the budget between monsoonal precipitation and continental evaporation7 crossed a tipping point such that the positive influence of temperature on evaporation became greater than its positive influence on precipitation. Our results imply that under continued anthropogenic warming, the Horn of Africa will probably experience further drying, and they highlight the need for improved simulation of both dynamic and thermodynamic processes in the tropical hydrological cycle.
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Affiliation(s)
- A J Baxter
- Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands.
| | - D Verschuren
- Department of Biology, Limnology Unit, Ghent University, Gent, Belgium
| | - F Peterse
- Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands
| | - D G Miralles
- Department of Environment, Hydro-Climate Extremes Lab (H-CEL), Ghent University, Gent, Belgium
| | | | - A Maitituerdi
- Dr. Moses Strauss Department of Marine Geosciences, Leon H. Charney School of Marine Sciences, University of Haifa, Mount Carmel, Israel
| | - T Van der Meeren
- Department of Biology, Limnology Unit, Ghent University, Gent, Belgium
| | - M Van Daele
- Renard Centre of Marine Geology, Department of Geology, Ghent University, Gent, Belgium
| | - C S Lane
- Department of Geography, University of Cambridge, Cambridge, UK
| | - G H Haug
- Department of Climate Geochemistry, Max Planck Institute for Chemistry, Mainz, Germany
| | - D O Olago
- Institute for Climate Change and Adaptation, Department of Earth and Climate Science, University of Nairobi, Nairobi, Kenya
| | - J S Sinninghe Damsté
- Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands
- Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, Den Burg, The Netherlands
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Dyke intrusion between neighbouring arc volcanoes responsible for 2017 pre-eruptive seismic swarm at Agung. Nat Commun 2019; 10:748. [PMID: 30765693 PMCID: PMC6376036 DOI: 10.1038/s41467-019-08564-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 01/16/2019] [Indexed: 11/19/2022] Open
Abstract
Forecasting explosive eruptions relies on using monitoring data to interpret the patterns and timescales of magma transport and mixing. In September 2017, a distal seismic swarm triggered the evacuation of around 140,000 people from Agung volcano, Bali. From satellite imagery and 3D numerical models, we show that seismicity was associated with a deep, sub-vertical magma intrusion between Agung and its neighbour Batur. This, combined with observations of the 1963 eruption which caused more than thousand fatalities, suggests a vertically and laterally interconnected system experiencing recurring magma mixing. The geometry of the 2017 dyke is consistent with transport from a deep mafic source to a shallow andesitic reservoir controlled by stresses induced by the topographic load, but not the regional tectonics. The ongoing interactions between Agung and Batur have important implications for interpretation of distal seismicity, the links between closely spaced arc volcanoes, and the potential for cascading hazards. Using seismic data and numerical modelling, here, the authors characterize the three-month period of unrest occurring prior to the 2017 Agung eruption (Bali, Indonesia). They observe a large uplift signal located at ~5 km from Agung summit corresponding to the emplacement of a 10 km deep magma intrusion between Agung edifice and Batur caldera, suggesting a potential magmatic connection between the two volcanic systems.
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Blegen N, Jicha BR, McBrearty S. A new tephrochronology for early diverse stone tool technologies and long-distance raw material transport in the Middle to Late Pleistocene Kapthurin Formation, East Africa. J Hum Evol 2018; 121:75-103. [DOI: 10.1016/j.jhevol.2018.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 03/14/2018] [Accepted: 03/20/2018] [Indexed: 10/16/2022]
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