December 1, 2022

From September to October of 2015, a 60-person workforce had been gathering on the Guliya ice cap within the Kunlun Mountains of the Tibetan Plateau, with the aim to retrieve the world’s oldest ice. In a FEATURES article printed in Science (29/01/2016) entitled “Tibet’s Primeval Ice: the hunt for the world’s oldest ice may yield a Rosetta Stone for the way Asia responds to a altering local weather”, it was written that “in faint layers of mud and fuel bubbles and refined variations in chemical substances throughout the ice, the glistening cylinder holds a part of a document of historical local weather on the Tibetan Plateau that would stretch again almost one million years”.

In reality, this isn’t the primary attempt for retrieving ice cores from the Guliya ice cap. In 1992, a Guliya ice core to bedrock (308.6 m in size) was recovered at an elevation of 6 200 m above sea degree. The 1992 Guliya core was featured on the duvet of Science printed on 6/20/1997 for its extraordinary long-time scale with the next introduction: “……The Guliya ice core to bedrock incorporates a regional local weather historical past for the complete final glacial cycle, and the basal ice could exceed 500 000 years in age”.

The courting outcomes have made the 1992 Guliya core the oldest non-polar core. As compared, the Vostok ice core (3 623 m in size) from the central East Antarctica yielded a local weather historical past of previous 420 000 years, and the EPICA Dome C ice core (3 260 m in size) additionally from the central East Antarctica yielded to date the longest ice core document of 800 000 years.

The Guliya ice core temperature document has been extensively used as a paleoclimatic reference since its publication in 1997. Nonetheless, its chronology was just lately challenged by a number of unbiased research. Cheng et al. argued that the chronology of the higher 266 m of the Guliya ice core wanted to be compressed by half with a purpose to reconcile the secure isotopic profiles of the Guliya ice core and the Kesang stalagmite information.

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In a latest paper printed in 2022, Wang et al. additional prompt that the Guliya ice core could have a basal age of ~70 000 years with a purpose to reconcile the secure isotopic variations between speleothem and Tibetan ice cores. The radiometric 81Kr courting of a number of ice samples collected from the sting of the Guliya ice cap yielded higher limits for the age of Guliya ice within the vary of 15 000-74 000 years. It’s obvious that these courting outcomes had been one order of magnitude youthful than the unique backside age estimates of the Guliya ice core.

Moreover, Hou et al. in contrast the secure isotopic profiles of the Guliya and its close by Chongce ice cores primarily based on their relative depth, and located vital optimistic correlation between the 2 information, implying an analogous timescale for each ice cores. Positioned solely ~30 km away from the Guliya ice core website, the Chongce ice cores had the estimated backside age of 9 000 and eight 300 years for the 135.8 m and the 216.6 m cores respectively.

Furthermore, the primary optically stimulated luminescence (OSL) courting of the basal sediment collected from the underside phase of the Chongce 216.6 m ice core resulted in an age estimation of 42 000 years, offering an higher restrict for the age of the Chongce ice cores.

Given the shut proximity between the Chongce and Guliya ice core drilling websites and the exceptional similarity between their secure isotopic profiles, the Holocene origin of the Chongce ice cores casts vital doubt on the distinctive size of the Guliya ice core document. Furthermore, all the opposite Tibetan ice cores, together with the Dunde and Shulenanshan within the Qilian mountains, Zangser Kangri and Puruogangri within the central Tibetan Plateau, and Dasuopu and East Rongbuk within the Himalayas, had been additionally prompt to be of Holocene origin.

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Courting alpine ice cores is at all times a difficult activity. Normally, layer counting primarily based on seasonal alerts within the bodily and chemical properties of the ice core is just dependable for the higher a part of the core because of speedy thinning of ice layers in deeper sections. For the deeper (older) a part of the ice cores, absolute courting strategies, normally primarily based on the decay of radioactive parts preserved within the ice cores, are wanted to determine the core chronology. Due to this fact, the brand new Guliya ice cores drilled in 2015 present a useful alternative to instantly confirm the chronology of the 1992 Guliya ice core, notably with the assistance of recent courting methods equivalent to 14C, 36Cl, 40Ar and 81Kr.

Such an effort is extraordinarily needed and pressing not just for establishing correct chronologies of Tibetan ice cores, but in addition for growing dependable reconstructions of previous local weather and testing vital local weather ideas and hypotheses, equivalent to asynchronous glaciation and Holocene temperature conundrum on the Tibetan Plateau.

Analysis Report:On the chronology of Tibetan ice cores

Associated Hyperlinks

College of Oceanography, Shanghai Jiao Tong College, China

Past the Ice Age

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Desert mud collected from glacier ice helps doc local weather change

Columbus OH (SPX) Nov 15, 2022

Researchers from The Ohio State College are utilizing mud trapped in glacier ice in Tibet to doc previous modifications in Earth’s intricate local weather system – and perhaps sooner or later assist predict future modifications.

Their findings counsel that the mud composition in samples collected from completely different areas and depths of the identical glacier can differ drastically, a discovery that hints {that a} full mud document may provide up extra secrets and techniques than scientists understand.

Mud stirred up by sturdy winds could cause a bunch of … learn extra

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