How old is the human footprint in the world's largest alpine ecosystem? A review of multiproxy records from the Tibetan Plateau from the ecologists' viewpoint

Miehe, Georg; Miehe, Sabine; Böhner, Jürgen; Kaiser, Knut; Hensen, Isabel; Madsen, David B.; Liu, Jianquan; Opgenoorth, Lars

doi:10.1016/j.quascirev.2013.12.004

Cited by 130 publications

(88 citation statements)

References 102 publications

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“…Human impact on global climate from agriculture and land clearing may have begun as early as the mid-Holocene [58,59], but earlier climate change was presumably devoid of anthropogenic influences. Characterizing past cycles of temperature fluctuation can therefore help inform the distinction between natural (non-anthropogenic) and anthropogenic forcing of climate in the present, as discussed further below.…”

Section: Discussionmentioning

confidence: 99%

The Antarctic Centennial Oscillation: A Natural Paleoclimate Cycle in the Southern Hemisphere That Influences Global Temperature

Davis

Taylor²,

Davis³

2018

Climate

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Abstract:We report a previously-unexplored natural temperature cycle recorded in ice cores from Antarctica-the Antarctic Centennial Oscillation (ACO)-that has oscillated for at least the last 226 millennia. Here we document the properties of the ACO and provide an initial assessment of its role in global climate. We analyzed open-source databases of stable isotopes of oxygen and hydrogen as proxies for paleo-temperatures. We find that centennial-scale spectral peaks from temperature-proxy records at Vostok over the last 10,000 years occur at the same frequencies (±2.4%) in three other paleoclimate records from drill sites distributed widely across the East Antarctic Plateau (EAP), and >98% of individual ACOs evaluated at Vostok match 1:1 with homologous cycles at the other three EAP drill sites and conversely. Identified ACOs summate with millennial periodicity to form the Antarctic Isotope Maxima (AIMs) known to precede Dansgaard-Oeschger (D-O) oscillations recorded in Greenland ice cores. Homologous ACOs recorded at the four EAP drill sites during the last glacial maximum appeared first at lower elevations nearest the ocean and centuries later on the high EAP, with latencies that exceed dating uncertainty >30-fold. ACO homologs at different drill sites became synchronous, however, during the warmer Holocene. Comparative spectral analysis suggests that the millennial-scale AIM cycle declined in period from 1500 to 800 years over the last 70 millennia. Similarly, over the last 226 millennia ACO repetition period (mean 352 years) declined by half while amplitude (mean 0.67 • C) approximately doubled. The period and amplitude of ACOs oscillate in phase with glacial cycles and related surface insolation associated with planetary orbital forces. We conclude that the ACO: encompasses at least the EAP; is the proximate source of D-O oscillations in the Northern Hemisphere; therefore affects global temperature; propagates with increased velocity as temperature increases; doubled in intensity over geologic time; is modulated by global temperature variations associated with planetary orbital cycles; and is the probable paleoclimate precursor of the contemporary Antarctic Oscillation (AAO). Properties of the ACO/AAO are capable of explaining the current global warming signal.

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Section: Discussionmentioning

confidence: 99%

The Antarctic Centennial Oscillation: A Natural Paleoclimate Cycle in the Southern Hemisphere That Influences Global Temperature

Davis

Taylor²,

Davis³

2018

Climate

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“…Alpine steppes cover an area of 800,000 km 2 in the northwest of the Tibetan Plateau (Zhang 1988;Miehe et al 2011), and Kobresia pastures cover an area of 450,000 km 2 in the southeast (Miehe et al 2008). Those Kobresia pastures are partly secondary grasslands after forests had been cleared since the mid-Holocene (Kaiser et al 2007;Miehe et al 2009Miehe et al , 2014. About 7.4 Pg C is estimated to be stored in the upper 1 m of Tibetan grasslands (Yang et al 2008).…”

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confidence: 99%

Land use change decreases soil carbon stocks in Tibetan grasslands

Qiao

Cao

et al. 2015

Plant Soil

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Backgrounds and aims Land use is an important factor affecting soil organic carbon (SOC) dynamics and can produce positive C climate feedback, but its effects remain unknown for Tibetan ecosystems. Methods Recent land use changes have converted the traditional winter Kobresia pastures of nomads in the northeastern Tibetan Plateau to Elymus pastures or even to cropland. Detailed SOC measurements up to 30-cm depth were combined with analysis of δ 13 C, δ 15 N, bulk density, microbial C, and N contents in three land use types. Results Bulk density was decreased by conversion from Kobresia pasture to cropland but increased by conversion to Elymus pasture. The loss of 1 % of SOC caused by land use change leads to δ 13

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“…Studies of pollen in lake sediments show that Kobresia and other dominant sedges emerged about 8,000 years ago, when early Tibetans began burning forests to convert them to grasslands for livestock 3 . The prehistoric grazing helped to create the thick root mat that blankets the vast plateau and that has stored 18.1 billion tonnes of organic carbon.…”

Section: Water Worriesmentioning

confidence: 99%

Trouble in Tibet

Qiu

2016

Nature

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How old is the human footprint in the world's largest alpine ecosystem? A review of multiproxy records from the Tibetan Plateau from the ecologists' viewpoint

Cited by 130 publications

References 102 publications

The Antarctic Centennial Oscillation: A Natural Paleoclimate Cycle in the Southern Hemisphere That Influences Global Temperature

The Antarctic Centennial Oscillation: A Natural Paleoclimate Cycle in the Southern Hemisphere That Influences Global Temperature

Land use change decreases soil carbon stocks in Tibetan grasslands

Trouble in Tibet

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