East African climate change and orbital forcing during the last 175 kyr BP

Trauth, Martin H.; Deino, Alan L.; Bergner, Andreas G.N.; Strecker, Manfred R.

doi:10.1016/s0012-821x(02)01105-6

Cited by 164 publications

(85 citation statements)

References 63 publications

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“…Indeed, the markedly deepened megadrought behavior over the last 450,000 y in particular, resembles the tempo of enhanced northern hemisphere glacial-interglacial variability during that time interval, and suggests a strong linkage to highlatitude forcing and Indo-Arabian monsoon dynamics, as indicated in some shorter tropical records (21,23). The lack of steady precessional rhythms in this terrestrial hydroclimate record is consistent with recent modeling efforts (24) that suggest that moisture transport in southeastern Africa is a more complex and nuanced process than previously postulated, and orbital forcing alone (2,5,(25)(26)(27)(28)) is insufficient to explain 10 4-5 -y moisture variability over million-year time frames. Calibrated lake level [the first principal component, PC (1)] demonstrates cyclic behavior from ∼200 to ∼600 ka ( Fig.…”

Section: Causative Mechanisms For Climate Variabilitysupporting

confidence: 86%

“…The extreme hydroclimate variability exerted a profound influence on the Lake Malawi endemic cichlid fish species flock; the geographically extensive habitat reconfiguration provided novel ecological opportunities, enabling new populations to differentiate rapidly to distinct species. Lake Malawi | tropical paleoclimatology | East African rift | cichlid fish | quaternary I nsolation forcing of tropical convection and shifts in the Intertropical Convergence Zone (ITCZ) are considered principal mechanisms driving tropical climate variability on geologic time scales (1)(2)(3)(4)(5). However, instrumental records show that the ITCZ over land is poorly characterized compared with the oceans (Fig.…”

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confidence: 99%

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Continuous 1.3-million-year record of East African hydroclimate, and implications for patterns of evolution and biodiversity

Lyons

Scholz

Cohen

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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120

164

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The transport of moisture in the tropics is a critical process for the global energy budget and on geologic timescales, has markedly influenced continental landscapes, migratory pathways, and biological evolution. Here we present a continuous, first-of-its-kind 1.3-My record of continental hydroclimate and lake-level variability derived from drill core data from Lake Malawi, East Africa (9-15°S). Over the Quaternary, we observe dramatic shifts in effective moisture, resulting in large-scale changes in one of the world's largest lakes and most diverse freshwater ecosystems. Results show evidence for 24 lake level drops of more than 200 m during the Late Quaternary, including 15 lowstands when water levels were more than 400 m lower than modern. A dramatic shift is observed at the Mid-Pleistocene Transition (MPT), consistent with far-field climate forcing, which separates vastly different hydroclimate regimes before and after ∼800,000 years ago. Before 800 ka, lake levels were lower, indicating a climate drier than today, and water levels changed frequently. Following the MPT high-amplitude lake level variations dominate the record. From 800 to 100 ka, a deep, often overfilled lake occupied the basin, indicating a wetter climate, but these highstands were interrupted by prolonged intervals of extreme drought. Periods of high lake level are observed during times of high eccentricity. The extreme hydroclimate variability exerted a profound influence on the Lake Malawi endemic cichlid fish species flock; the geographically extensive habitat reconfiguration provided novel ecological opportunities, enabling new populations to differentiate rapidly to distinct species. Lake Malawi | tropical paleoclimatology | East African rift | cichlid fish | quaternary I nsolation forcing of tropical convection and shifts in the Intertropical Convergence Zone (ITCZ) are considered principal mechanisms driving tropical climate variability on geologic time scales (1-5). However, instrumental records show that the ITCZ over land is poorly characterized compared with the oceans (Fig. 1), and the transport of oceanic moisture to the hinterlands is complex, because topographic barriers redirect winds and block advection to the continental interiors (6). To document moisture transport onto the continents over geological time scales, terrestrial records of tropical paleoclimate with the length and continuity of ocean drilling records are required. Continental drilling in long-lived tropical lakes provides continuous, high-resolution paleoclimate records that extend well past the last glacial maximum (7,8), and augment shorter, well-dated records from outcrops. Lakes of great antiquity also contain numerous endemic species-notably, cichlid fishes-whose modern assemblages evolved in concert with changing climates, and which figure prominently into models of speciation and diversification (9, 10).Lake Malawi and Its Catchment Lake Malawi (Nyasa) is one of the world's largest and oldest lakes, and is situated at the southern end of the East Afri...

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Section: Causative Mechanisms For Climate Variabilitysupporting

confidence: 86%

mentioning

confidence: 99%

Continuous 1.3-million-year record of East African hydroclimate, and implications for patterns of evolution and biodiversity

Lyons

Scholz

Cohen

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

120

164

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“…Berger et al (2006) demonstrated the presence of an 11-kyr period in modern equatorial insolation. This sub-Milanković period, which is a harmonic of precession, is claimed to occur in paleoclimate archives of modern monsoonal systems (Hagelberg et al, 1994;Trauth et al, 2003;Turney et al, 2004;Sun and Huang, 2006;Verschuren et al, 2009). Several mechanisms were suggested to explain how the 11-kyr astronomical cycle is transferred to climate: an amplified response of tropical precipitation and temperature to changes in maximum summer insolation in both hemispheres (Hagelberg et al, 1994), atmospheric and oceanic teleconnections (Turney et al, 2004), low-latitude precipitation intensity on precession.…”

Section: Palaeoclimatological Interpretationmentioning

confidence: 99%

Precessional and half-precessional climate forcing of Mid-Devonian monsoon-like dynamics

Vleeschouwer

Silva²,

Boulvain³

et al. 2012

Clim. Past

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Abstract.A Devonian magnetic susceptibility (MS) record obtained on limestones ranging from the Uppermost-Eifelian to the Lower-Givetian and located on the southern border of the Dinant Synclinorium in Belgium was selected for timeseries analysis. In these carbonate ramp and platform deposits, spectral analyses highlight persistent, high-frequency cycles in both the MS-signal and the microfacies curve, reflecting environmental and climate changes. These metrescale variations in the MS-signal are interpreted as changes in the flux of magnetic minerals towards the marine system, most likely controlled by monsoon rainfall-intensity. By combining chrono-and biostratigraphic information with theoretical knowledge of sedimentation rates in different depositional environments, these cycles are interpreted as astronomically driven and dominated by precession. It is hypothesized that during precession minima (longitude of the perihelion ≈270 • ) the trans-equatorial pressure gradient reaches a maximum and intensifies the northeasterly monsoonal circulation. The consequent increase in moisture transport towards the continent leads to enhanced precipitation and runoff, which, in turn, induces a higher flux of detrital material -including magnetic minerals responsible for the MS-signal -towards the marine system. Moreover, this unique high-resolution climate signal reveals halfprecessional cycles. These cycles suggest that during precession maxima (longitude of the perihelion ≈90 • ) southeasterly monsoonal circulation strengthened due to an increased inter-hemispheric pressure gradient.

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“…A conspicuous increase in the significance for obliquity and precession is noticeable. The spectra in c and d were calculated with software REDFIT 3.8 high-latitude and East African climate are known for the tropical Pleistocene (Trauth et al 2003;Turney et al 2004). But, sub-Milankovitch cyclicity in the Messel oil shale is part of an ongoing detailed study.…”

Section: Trends and Cyclesmentioning

confidence: 99%

Short-term fluctuations in vegetation and phytoplankton during the Middle Eocene greenhouse climate: a 640-kyr record from the Messel oil shale (Germany)

Lenz

Wilde

Riegel

2010

Int J Earth Sci (Geol Rundsch)

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The Palaeogene was the most recent greenhouse period on Earth. Especially for the Late Palaeocene and Early Eocene, several superimposed short-term hyperthermal events have been described, including extremes such as the Palaeocene-Eocene Thermal Maximum. Major faunal and floral turnovers in the marine and terrestrial realms were recorded in association with these events. High-resolution palynological analysis of the early Middle Eocene maar lake sediments at Messel, near Darmstadt, Germany, provides an insight into the dynamics of a climax vegetation during the Middle Eocene greenhouse climate in a time span without significant climatic excursions. Numerical techniques like detrended correspondence analysis and wavelet analysis have been applied to recognize cyclic fluctuations and long-term trends in the vegetation through a time interval of approximately 640 kyr. Based on the numerical zoning of the pollen diagram, three phases in the development of the vegetation may be distinguished. Throughout these phases, the climax vegetation did not change substantially in qualitative composition, but a trend towards noticeably less humid conditions probably in combination with a drop of the water level in the lake may be recognized. A shift in algal population from the freshwater dinoflagellate cyst Messelodinium thielepfeifferae to a dominance of Botryococcus in the uppermost part of the core is interpreted as a response to changes in acidity and nutrient availability within the lake. Time series analyses of pollen assemblages show that variations in the Milankovitch range of eccentricity, obliquity and precession can be distinguished. In addition, fluctuations in the sub-Milankovitch range are indicated. This demonstrates that floral changes during steady depositional conditions in the Middle Eocene of Messel were controlled by orbital forcing.

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East African climate change and orbital forcing during the last 175 kyr BP

Cited by 164 publications

References 63 publications

Continuous 1.3-million-year record of East African hydroclimate, and implications for patterns of evolution and biodiversity

Continuous 1.3-million-year record of East African hydroclimate, and implications for patterns of evolution and biodiversity

Precessional and half-precessional climate forcing of Mid-Devonian monsoon-like dynamics

Short-term fluctuations in vegetation and phytoplankton during the Middle Eocene greenhouse climate: a 640-kyr record from the Messel oil shale (Germany)

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