Mid-Pliocene climate change amplified by a switch in Indonesian subsurface throughflow

Karas, Cyrus; Nürnberg, Dirk; Gupta, Anil K.; Tiedemann, Ralf; Mohan, Kshitij; Bickert, Torsten

doi:10.1038/ngeo520

Cited by 162 publications

(185 citation statements)

References 31 publications

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“…Recent paleoceanographic reconstructions revealed that, during the Pliocene, subsurface waters in the eastern tropical Indian Ocean freshened and cooled by about 4 K, including a major cooling step between 3.5 and 2.95 Ma B.P. (63). Although SSTwas much less affected in most parts of the Indian Ocean, the southern coast of the Arabian Peninsula as well as the region around the horn of Africa are known as (wind-driven seasonal) upwelling regions (61,64), which suggests that cold subsurface waters could have (at least intermittently) reached the ocean surface in this area and, thus, have led to a considerable decrease in the average regional SST.…”

Section: Discussionmentioning

confidence: 99%

Nonlinear detection of paleoclimate-variability transitions possibly related to human evolution

Donges

Donner²,

Trauth³

et al. 2011

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

218

163

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Potential paleoclimatic driving mechanisms acting on human evolution present an open problem of cross-disciplinary scientific interest. The analysis of paleoclimate archives encoding the environmental variability in East Africa during the past 5 Ma has triggered an ongoing debate about possible candidate processes and evolutionary mechanisms. In this work, we apply a nonlinear statistical technique, recurrence network analysis, to three distinct marine records of terrigenous dust flux. Our method enables us to identify three epochs with transitions between qualitatively different types of environmental variability in North and East Africa during the (i) Middle Pliocene (3.35-3.15 Ma B.P.), (ii) Early Pleistocene (2.25-1.6 Ma B.P.), and (iii) Middle Pleistocene (1.1-0.7 Ma B.P.). A deeper examination of these transition periods reveals potential climatic drivers, including (i) large-scale changes in ocean currents due to a spatial shift of the Indonesian throughflow in combination with an intensification of Northern Hemisphere glaciation, (ii) a global reorganization of the atmospheric Walker circulation induced in the tropical Pacific and Indian Ocean, and (iii) shifts in the dominating temporal variability pattern of glacial activity during the Middle Pleistocene, respectively. A reexamination of the available fossil record demonstrates statistically significant coincidences between the detected transition periods and major steps in hominin evolution. This result suggests that the observed shifts between more regular and more erratic environmental variability may have acted as a trigger for rapid change in the development of humankind in Africa.African climate | Plio-Pleistocene | climate-driven evolution | dynamical transitions | nonlinear time series analysis R ecent comparisons of terrestrial and marine paleoclimate archives have resulted in an intense debate concerning global vs. regional forcing of East Africa's climate and its relationship to human evolution during the past 5 Ma (1-4). The gradual longterm retreat of equatorial rain forests and the emergence of drier environments in East Africa (2, 5, 6) were interrupted by distinct epochs of increased humidity indicated by paleo-lake levels in different basins of the East African Rift System (EARS) displaying synchronous highs at about 2.7-2.5, 1.9-1.7, and 1.1-0.9 Ma B.P. (7). Notably, these epochs coincide well with certain global-scale climate transitions like the final closure of the Panama isthmus (8-10), intensification of the atmospheric Walker circulation (11), and the shift from a predominance of obliquity-driven glacial variability (41 ka period) to glacial-interglacial cycles with a 100 ka period (12, 13). Further reconstructions revealed additional relevant lake periods at 4.7-4.3, 4.0-3.9, 3.4-3.3, and 3.2-2.95 Ma B.P. (3). Previous findings suggest that the dominating summer aridity in the East African climate was controlled mainly by orbitally driven changes in the local irradiation driving regional monsoon activity via changes of sea-surf...

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Section: Discussionmentioning

confidence: 99%

Nonlinear detection of paleoclimate-variability transitions possibly related to human evolution

Donges

Donner²,

Trauth³

et al. 2011

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

218

163

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“…Karas et al (2009) attribute subsurface cooling to the same mechanism of ocean gateway change and switch to cooler North Pacific source waters, but in their scenario subsurface cooling in the East Indian Ocean forced a shoaling of the thermocline and affected the subsurface waters in the west too, through equatorial and coastal upwelling off Somalia.…”

Section: Tropical Pacificmentioning

confidence: 99%

Climate and environment of a Pliocene warm world

Salzmann

Williams

Haywood

et al. 2011

Palaeogeography, Palaeoclimatology, Palaeoecology

158

105

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The Pliocene Epoch, 5.33 -2.58 million years ago (Ma), was a generally warmer and wetter interval with atmospheric CO 2 -concentrations at or slightly above modern levels. This paper provides an overview of Pliocene vegetation, sea surface temperatures and climate modelling outcomes.. Most prominent changes in Pliocene biome distribution compared to today include a northwards shift of temperate and boreal vegetation zones in response to a warmer and wetter climate as well as an expansion of tropical savannas and forests at the expense of deserts. Modelling experiments using the Hadley Centre climate model identified significantly higher Pliocene sea surface temperatures at the high-latitudes with only minor warming predicted in the tropics. Global mean annual surface temperatures (MAT) are estimated to have been 2 to 3ºC higher during the Piacenzian (3.6-2.58 Ma) than today with a reduced equator to pole gradient. The marine realm during the Pliocene was characterised by a reconfiguration of ocean gateways, particularly the narrowing of the Indonesian Seaway and closure of the Central American Isthmus, which produced essentially a modern pattern of ocean circulation. In the Southern Ocean a warm early Pliocene gave way to late Piacenzian cooling. Proxy data indicate a reduced east to west sea surface temperature gradient in the tropical Pacific during the Pliocene warmth. The Pliocene is one of the most intensively studied geological intervals of the pre-Quaternary. No other warm period in the geological past yields such a unique combination of near modern atmospheric CO 2 -concentrations, palaeogeography and palaeobiology. However, this paper also identifies data gaps and shortcomings in the reconstruction of Pliocene environments using proxy data and climate models on which future research should focus.

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“…However, relatively warm SSTs in the Southern Ocean during our study interval (∼ 10.5-17 • C at ODP Site 1090, Martínez-Garcia et al, 2010; Fig. 1a, -a site accepted as the best end-member of Southern Ocean waters, Billups et al, 2002;Pusz et al, 2011) are difficult to reconcile with substantially lower temperatures recorded in thermocline waters at EEP Site 849 (∼ 1-11.6 • C; this study) and Indian Ocean Site 214 (∼ 8-10 • C; Karas et al, 2009 iii. Thermocline temperatures of the Last Glacial Maximum are expected to be substantially colder than those of the Plio-Pleistocene transition (Ford et al, 2012).…”

Section: Mg / Ca-based Temperature Datamentioning

confidence: 99%

“…This size fraction was selected to keep ontogenetic effects as small as possible (Elderfield et al, 2002; Jakob et al (2017) et al, 2012) but at the same time to allow for a sufficient number of G. crassaformis tests per sample. Moreover, the 315-400 µm fraction ensured the highest comparability to previous geochemical records of this species (e.g., Karas et al, 2009;Jakob et al, 2016). Tests for δ 18 O and Mg / Ca analyses were cracked, homogenized and split into two subsamples.…”

Section: Sample Materialsmentioning

confidence: 99%

Thermocline state change in the eastern equatorial Pacific during the late Pliocene/early Pleistocene intensification of Northern Hemisphere glaciation

et al. 2018

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Abstract. The late Pliocene/early Pleistocene intensification of Northern Hemisphere glaciation (iNHG) ∼ 2.5 million years ago (marine isotope stages, MIS, 100-96) stands out as an important tipping point in Earth's climate history, which strongly influenced oceanographic and climatic patterns including trade wind and upwelling strength in the eastern equatorial Pacific (EEP). The thermocline depth in the EEP, in turn, plays a pivotal role in the Earth's climate system: small changes in its depth associated with short-term climate phenomena such as the El Niño-Southern Oscillation can affect surface-water properties and the ocean-atmosphere exchange. However, thermocline dynamics in the EEP during the iNHG still remain unclear. While numerous studies have suggested a link between a thermocline shoaling in the EEP and Northern Hemisphere ice growth, other studies have indicated a stable thermocline depth during the iNHG; consequently, a causal relationship between thermocline dynamics and ice-sheet growth has been excluded. In light of these contradictory views, we have generated geochemical (planktic foraminiferal δ 18 O, δ 13 C and Mg / Ca), sedimentological (sand accumulation rates) and faunal (abundance data of thermocline-dwelling foraminifera) records for Ocean Drilling Program Site 849 located in the central region of the EEP. Our records span the interval from ∼ 2.75 to 2.4 Ma (MIS G7-95), which is critical for understanding thermocline dynamics during the final phase of the iNHG. Our new records document a thermocline shoaling from ∼ 2.64 to 2.55 Ma (MIS G2-101) and a relatively shallow thermocline from ∼ 2.55 Ma onwards . This indicates a state change in thermocline depth at Site 849 shortly before the final phase of the iNHG. Ultimately, our data support the hypothesis that (sub-)tropical thermocline shoaling may have contributed to the development of large Northern Hemisphere ice sheets.

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Mid-Pliocene climate change amplified by a switch in Indonesian subsurface throughflow

Cited by 162 publications

References 31 publications

Nonlinear detection of paleoclimate-variability transitions possibly related to human evolution

Nonlinear detection of paleoclimate-variability transitions possibly related to human evolution

Climate and environment of a Pliocene warm world

Thermocline state change in the eastern equatorial Pacific during the late Pliocene/early Pleistocene intensification of Northern Hemisphere glaciation

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